U.S. patent application number 11/691257 was filed with the patent office on 2007-10-18 for stitching of paths for improved text-on-path rendering of map labels.
This patent application is currently assigned to RESEARCH IN MOTION LIMITED. Invention is credited to Gordon Gregory BOWMAN, Eric JOHNSON, Gerhard Dietrich KLASSEN.
Application Number | 20070242084 11/691257 |
Document ID | / |
Family ID | 37037009 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070242084 |
Kind Code |
A1 |
BOWMAN; Gordon Gregory ; et
al. |
October 18, 2007 |
STITCHING OF PATHS FOR IMPROVED TEXT-ON-PATH RENDERING OF MAP
LABELS
Abstract
A wireless communications device obtains sets of map data for
rendering portions of a map on a display of the device. The map
data includes label data for rendering labels on the map for
identifying map features. Once the map data is obtained, the
wireless device generates a list of all the labels to be rendered
on the map, and for each duplicated label in the list, determines
whether the map features associated with the duplicated labels
connect on the map. If the labels connect, the device then
generates a reconstructed map feature and renders a single instance
of the label for the map feature. Accordingly, a map feature, such
as a path, can be rendered with a single label even if the map data
for the map feature, including its associated labels, was
transmitted over-the-air as discrete sets of data.
Inventors: |
BOWMAN; Gordon Gregory;
(Kemptville, CA) ; KLASSEN; Gerhard Dietrich;
(Waterloo, CA) ; JOHNSON; Eric; (Ottawa,
CA) |
Correspondence
Address: |
OGILVY RENAULT LLP
1981 MCGILL COLLEGE AVENUE
SUITE 1600
MONTREAL
QC
H3A2Y3
CA
|
Assignee: |
RESEARCH IN MOTION LIMITED
295 Phillip Street
Waterloo
CA
|
Family ID: |
37037009 |
Appl. No.: |
11/691257 |
Filed: |
March 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60788434 |
Mar 31, 2006 |
|
|
|
60787541 |
Mar 31, 2006 |
|
|
|
Current U.S.
Class: |
345/629 ;
345/619 |
Current CPC
Class: |
G01C 21/367 20130101;
G06T 17/05 20130101; G09G 2340/0492 20130101; G06T 19/00 20130101;
G06T 2219/004 20130101; G06F 3/147 20130101; G06F 3/0481 20130101;
G06T 15/503 20130101; G08G 1/096805 20130101; G06F 16/9577
20190101; G06F 40/103 20200101; G09G 5/377 20130101; G08G 1/0969
20130101; G09G 2340/145 20130101; G09B 29/106 20130101; G01C
21/3673 20130101; G09G 2340/10 20130101; G09B 29/10 20130101; G06T
11/60 20130101; G06F 16/29 20190101 |
Class at
Publication: |
345/629 ;
345/619 |
International
Class: |
G09G 5/00 20060101
G09G005/00 |
Claims
1. A method of displaying a map on a wireless communications
device, the method comprising steps of: obtaining sets of map data
for rendering portions of the map on a display of the device, the
map data including label data for rendering labels on the map for
identifying one or more map features; generating a list of all the
labels to be rendered on the map; for each duplicated label in the
list, determining whether the map features associated with the
duplicated labels connect on the map; generating a reconstructed
map feature; and rendering a single instance of the label for the
map feature.
2. The method as claimed in claim 1 wherein the step of rendering
the single instance of the label comprises a step of rendering the
label such that the label is aligned with a middle of the
reconstructed map feature.
3. The method as claimed in claim 1 wherein the reconstructed map
feature is a reconstructed path that is reconstructed from
constituent path segments derived from separate sets of map
data.
4. The method as claimed in claim 3 wherein the step of determining
whether the map features associated with the duplicated labels
connect on the map comprises a step of determining whether a first
endpoint of a first path associated with the duplicated label
matches a second endpoint of a second path also associated with the
duplicated label.
5. The method as claimed in claim 4 wherein the step of rendering
the single instance of the label comprises a step of rendering the
label midway along the reconstructed path.
6. The method as claimed in claim 1 wherein the step of generating
the reconstructed map feature comprises steps of: determining a
direction of a data vector for each constituent set of map data
that, when rendered, together constitutes the reconstructed map
feature; and reversing the direction of one or more data vectors so
that all data vectors in the reconstructed map feature have a
common direction.
7. The method as claimed in claim 3 wherein the step of generating
the reconstructed map feature comprises steps of: determining a
direction of a data vector for each constituent set of map data
that, when rendered, together constitutes the reconstructed path;
and reversing the direction of one or more data vectors so that all
data vectors corresponding to each constituent path segment in the
reconstructed path have a common direction.
8. The method as claimed in claim 3 wherein the step of generating
the reconstructed path comprises a step of storing a length of each
constituent path segment and a total length of the reconstructed
path.
9. The method as claimed in claim 7 wherein the step of generating
the reconstructed path comprises a step of storing a length of each
constituent path segment and a total length of the reconstructed
path.
10. The method as claimed in claim 1 wherein the step of generating
the list comprises a step of sorting the labels into alphabetical
order.
11. A computer program product comprising code adapted to perform
the steps of claim 1 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
12. The computer program product comprising code adapted to perform
the steps of claim 2 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
13. The computer program product comprising code adapted to perform
the steps of claim 3 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
14. The computer program product comprising code adapted to perform
the steps of claim 4 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
15. The computer program product comprising code adapted to perform
the steps of claim 5 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
16. The computer program product comprising code adapted to perform
the steps of claim 6 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
17. The computer program product comprising code adapted to perform
the steps of claim 7 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
18. The computer program product comprising code adapted to perform
the steps of claim 8 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
19. The computer program product comprising code adapted to perform
the steps of claim 9 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
20. The computer program product comprising code adapted to perform
the steps of claim 10 when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
21. A wireless communications device for enabling a user of the
device to display a map on the device, the wireless device
comprising: an input device for enabling the user to cause the
device to obtain map data for rendering the map to be displayed on
a display of the device, the map data including label data for
rendering labels on the map for identifying one or more map
features; and a memory for storing code to instruct a processor to:
generate a list of all the labels to be rendered on the map;
determine, for each duplicated label in the list, whether the map
features associated with the duplicated labels connect on the map;
generate a reconstructed map feature; and render on the display of
the device a single instance of the label for the map feature.
22. The wireless communications device as claimed in claim 21
wherein the processor renders the label such that the label is
aligned with a middle of the reconstructed map feature.
23. The wireless communications device as claimed in claim 21
wherein the reconstructed map feature is a reconstructed path that
is reconstructed from constituent path segments derived from
separate sets of map data.
24. The wireless communications device as claimed in claim 23
wherein the processor determines whether a first endpoint of a
first path associated with the duplicated label matches a second
endpoint of a second path also associated with the duplicated
label.
25. The wireless communications device as claimed in claim 24
wherein processor renders the single instance of the label midway
along the reconstructed path.
26. The wireless communications device as claimed in claim 21
wherein the processor determines a direction of a data vector for
each constituent set of map data that, when rendered, together
constitutes the reconstructed map feature and then reverses the
direction of one or more data vectors so that all data vectors in
the reconstructed map feature have a common direction.
27. The wireless communications device as claimed in claim 23
wherein the processor determines a direction of a data vector for
each constituent set of map data that, when rendered, together
constitutes the reconstructed path and then reverses the direction
of one or more data vectors so that all data vectors corresponding
to each constituent path segment in the reconstructed path have a
common direction.
28. The wireless communications device as claimed in claim 23
wherein the processor causes the memory to store a length of each
constituent path segment and a total length of the reconstructed
path.
29. The wireless communications device as claimed in claim 27
wherein the processor causes the memory to store a length of each
constituent path segment and a total length of the reconstructed
path.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application No. 60/788,434 entitled "Methods and Apparatus
for Dynamically Labelling Map Objects in Visually Displayed Maps of
Mobile Communication Devices" filed on Mar. 31, 2006 and from U.S.
Provisional Patent Application No. 60/787,541 entitled "Method and
System for Distribution of Map Content to Mobile Communication
Devices" filed on Mar. 31, 2006.
TECHNICAL FIELD
[0002] The present disclosure relates generally to wireless
communications devices and, in particular, to techniques for
generating map content on wireless communications devices.
BACKGROUND
[0003] Wireless communications devices such as the BlackBerry.TM.
by Research in Motion Limited enable users to download map content
from web-based data sources such as BlackBerry Maps.TM., Google
Maps.TM. or Mapquest.TM.. Downloaded map content is displayed on a
small LCD display screen of the wireless communications device for
viewing by the user. The user can pan up and down and side to side
as well as zoom in or out. Due to the small display on the device
and due to the limited over-the-air (OTA) bandwidth, there is a
need to optimize the delivery and handling of the map data.
[0004] With the increasing availability of wireless communications
devices having onboard Global Positioning System (GPS) receivers
for providing location-based services (LBS), the efficient delivery
and handling of map data is increasingly important.
[0005] Map data, including label data for labelling map features,
is communicated from map servers to wireless communications devices
in discrete portions which are assembled client-side to provide the
map content requested by the user. However, when reconstructing a
map from discrete portions of data, however, redundant labelling
can occur if labels associated with each portion of data are
rendered for the same feature. Furthermore, even if redundant
labels are suppressed, the label associated with a reconstructed
map feature cannot be placed aesthetically in the center of the
reconstructed feature but rather is placed in the center of one of
the constituent elements of the feature.
[0006] Accordingly, a technique for efficiently and aesthetically
labelling maps reconstructed from discrete portions of downloaded
data remains highly desirable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Further features and advantages of the present technology
will become apparent from the following detailed description, taken
in combination with the appended drawings, in which:
[0008] FIG. 1 is a block diagram schematically illustrating
pertinent components of a wireless communications device and of a
wireless communications network;
[0009] FIG. 2 is a more detailed block diagram of a wireless
communications device;
[0010] FIG. 3A is a system diagram of network components which
provide mapping functionality in the wireless communications
devices of FIG. 1 and FIG. 2;
[0011] FIG. 3B illustrates a message exchange between a wireless
communications device and a map server for downloading map content
to the wireless communications device based on the system of FIG.
3A;
[0012] FIG. 3C is a diagram showing a preferred Maplet data
structure;
[0013] FIG. 4 is a schematic depiction of a wireless network having
an applications gateway for optimizing the downloading of map data
from map servers to wireless communications devices;
[0014] FIG. 5 is a flowchart presenting steps of a method of
displaying a map on a wireless device by stitching together
constituent path segments to generate a reconstructed path having a
single label associated with the reconstructed path;
[0015] FIG. 6 schematically depicts the potential problem of
redundant labelling that may be encountered when map features are
rendered from discrete sets of map data;
[0016] FIG. 7 schematically depicts the potential problems of
having both poorly placed labels and highly constrained labels that
may be encountered when map features are rendered from discrete
sets of map data by blindly squelching duplicated labels;
[0017] FIG. 8 schematically depicts a process of stitching together
path segments (and constituent elements of other map features) to
create reconstructed paths (and map features);
[0018] FIG. 9A schematically depicts constructing a label list with
link, vector, and flag information for efficiently stitching
together the map features of FIG. 6;
[0019] FIG. 9B schematically depicts a process of determining
whether an endpoint of one path associated with a duplicated label
matches an endpoint of another path having the same duplicated
label;
[0020] FIG. 9C schematically depicts a process of determining
vector directionality for vector map data;
[0021] FIG. 10 is a screenshot of a street map of downtown Ottawa,
Canada without stitching (reconstruction) of paths; and
[0022] FIG. 11 is a screenshot of a street map of downtown Ottawa,
Canada with stitching (reconstruction) of paths.
[0023] It will be noted that throughout the appended drawings, like
features are identified by like reference numerals.
DETAILED DESCRIPTION
[0024] The present technology provides, in general, a method of
rendering a map on a display of a wireless communications device
where the map data, including label data, is downloaded
over-the-air in small, discrete portions or sets of data, each with
its own label data for labelling features of the map. The wireless
device generates a list of all the labels to be rendered on the
map, and for each duplicated label in the list, determines whether
the map features associated with the duplicated labels connect or
coincide on the map. If the map features associated with the
duplicated labels do coincide, a map application running on the
device then generates a reconstructed map feature and renders a
single (preferably centrally-positioned) instance of the label for
the map feature. Accordingly, a map feature, such as a path, can be
rendered with a single label even if the map data for the map
feature, including its associated labels, was transmitted
over-the-air as discrete sets of data containing redundant
labels.
[0025] Thus, an aspect of the present technology is a method of
displaying a map on a wireless communications device. The method
includes steps of obtaining sets of map data for rendering portions
of the map on a display of the device, the map data including label
data for rendering labels on the map for identifying one or more
map features and generating a list of all the labels to be rendered
on the map. For each duplicated label in the list, the method
entails determining whether the map features associated with the
duplicated labels connect on the map. Finally, a reconstructed map
feature is generated and a single instance of the label is rendered
for the map feature.
[0026] Another aspect of the present technology is a computer
program product that includes code adapted to perform the steps of
the foregoing method when the computer program product is loaded
into memory and executed on a processor of a wireless
communications device.
[0027] Yet another aspect of the present technology is a wireless
communications device for enabling a user of the device to display
a map on the device. The wireless device includes an input device
for enabling the user to cause the device to obtain map data for
rendering the map to be displayed on a display of the device, the
map data including label data for rendering labels on the map for
identifying one or more map features. The wireless communications
device further includes a memory for storing code to instruct a
processor to generate a list of all the labels to be rendered on
the map, determine, for each duplicated label in the list, whether
the map features associated with the duplicated labels connect on
the map, generate a reconstructed map feature, and render on the
display of the device a single instance of the label for the map
feature.
[0028] The details and particulars of these aspects of the
technology will now be described below, by way of example, with
reference to the attached drawings.
[0029] FIG. 1 is a block diagram of a communication system 100
which includes a wireless communications device 102 (also referred
to as a mobile communications device) which communications through
a wireless communication network 104. For the purposes of the
present specification, the expression "wireless communications
device" encompasses not only a wireless handheld, cell phone or
wireless-enabled laptop but also any mobile communications device
or portable communications device such as a satellite phone,
wireless-enabled PDA or wireless-enabled MP3 player. In other
words, for the purposes of this specification, "wireless" shall be
understood as encompassing not only standard cellular or microwave
RF technologies, but also any other communications technique that
conveys data over the air using an electromagnetic signal.
[0030] The wireless communications device 102 preferably includes a
visual display 112, e.g. an LCD screen, a keyboard 114 (or keypad),
and optionally one or more auxiliary user interfaces (UI) 116, each
of which is coupled to a controller 106. The controller 106 is also
coupled to radio frequency (RF) transceiver circuitry 108 and an
antenna 110. Typically, controller 106 is embodied as a central
processing unit (CPU) which runs operating system software in a
memory device (described later with reference to FIG. 2).
Controller 106 normally controls the overall operation of the
wireless communications device 102, whereas signal processing
operations associated with communications functions are typically
performed in the RF transceiver circuitry 108. Controller 106
interfaces with the display screen 112 to display received
information, stored information, user inputs, and the like.
Keyboard/keypad 114, which may be a telephone-type keypad or a full
QWERTY keyboard, is normally provided for entering commands and
data.
[0031] The wireless communications device 102 sends communication
signals to and receives communication signals from network 104 over
a wireless link via antenna 110. RF transceiver circuitry 108
performs functions similar to those of station 118 and Base Station
Controller (BSC) 120, including, for example, modulation and
demodulation, encoding and decoding, and encryption and decryption.
It will be apparent to those skilled in the art that the RF
transceiver circuitry 108 will be adapted to the particular
wireless network or networks in which the wireless communications
device is intended to operate.
[0032] The wireless communications device 102 includes a battery
interface 134 for receiving one or more rechargeable batteries 132.
Battery 132 provides electrical power to electrical circuitry in
the device 102, and battery interface 134 provides for a mechanical
and electrical connection for battery 132. Battery interface 134 is
couple to a regulator 136 which regulates power to the device. When
the wireless device 102 is fully operationally, an RF transmitter
of RF transceiver circuitry 108 is typically keyed or turned on
only when it is sending to network, and is otherwise turned off to
conserve resources. Similarly, an RF receiver of RF transceiver
circuitry 108 is typically periodically turned off to conserve
power until it is needed to receive signals or information (if at
all) during designated time periods.
[0033] Wireless communications device 102 operates using a
Subscriber Identity Module (SIM) 140 which is connected to or
inserted in the wireless communications device 102 at a SIM
interface 142. SIM 140 is one type of a conventional "smart card"
used to identify an end user (or subscriber) of wireless device 102
and to personalize the device, among other things. Without SIM 140,
the wireless communications device 102 is not fully operational for
communication through wireless network 104. By inserting the SIM
card 140 into the wireless communications device 102, an end user
can have access to any and all of his subscribed services. SIM 140
generally includes a processor and memory for storing information.
Since SIM 140 is coupled to SIM interface 142, it is coupled to
controller 106 through communication lines 144. In order to
identify the subscriber, SIM 140 contains some user parameters such
as an International Mobile Subscriber Identity (IMSI). An advantage
of using SIM 140 is that end users are not necessarily bound by any
single physical wireless device. SIM 140 may store additional user
information for the wireless device as well, including datebook
(calendar) information and recent call information.
[0034] The wireless communications device 102 may consist of a
single unit, such as a data communication device, a cellular
telephone, a Global Positioning System (GPS) unit, a
multiple-function communication device with data and voice
communication capabilities, a wireless-enabled personal digital
assistant (PDA), or a wireless-enabled laptop computer.
Alternatively, the wireless communications device 102 may be a
multiple-module unit comprising a plurality of separate components,
including but in no way limited to a computer or other device
connected to a wireless modem. In particular, for example, in the
block diagram of FIG. 1, RF circuitry 108 and antenna 110 may be
implemented as a radio modem unit that may be inserted into a port
on a laptop computer. In this case, the laptop computer would
include display 112, keyboard 114, one or more auxiliary UIs 116,
and controller 106 embodied as the computer's CPU.
[0035] The wireless communications device 102 communicates in and
through a wireless communication network 104. The wireless
communication network may be a cellular telecommunications network.
In the example presented in FIG. 1, wireless network 104 is
configured in accordance with Global Systems for Mobile
communications (GSM) and General Packet Radio Service (GPRS)
technologies. Although wireless communication network 104 is
described herein as a CSM/GPRS-type network, any suitable network
technologies may be utilized such as Code Division Multiple Access
(CDMA), Wideband CDMA (WCDMA), whether 2G, 3G, or Universal Mobile
Telecommunication System (UMTS) based technologies. In this
example, the GSM/GPRS wireless network 104 includes a base station
controller (BSC) 120 with an associated tower station 118, a Mobile
Switching Center (MSC) 122, a Home Location Register (HER) 132, a
Serving General Packet Radio Service (GPRS) Support Node (SGSN)
126, and a Gateway GPRS Support Node (GGSN) 128. MSC 122 is coupled
to BSC 120 and to a landline network, such as a Public Switched
Telephone Network (PSTN) 124. SGSN 126 is coupled to BSC 120 and to
GGSN 128, which is, in turn, coupled to a public or private data
network 130 (such as the Internet). HELR 132 is coupled to MSC 122,
SGSN 126 and GGSN 128.
[0036] Tower station 118 is a fixed transceiver station. Tower
station 118 and BSC 120 may be referred to as transceiver
equipment. The transceiver equipment provides wireless network
coverage for a particular coverage area commonly referred to as a
"cell". The transceiver equipment transmits communication signals
to and receives communication signals from wireless communications
devices 102 within its cell via station 118. The transceiver
equipment normally performs such functions as modulation and
possibly encoding and/or encryption of signals to be transmitted to
the wireless communications device in accordance with particular,
usually predetermined, communication protocols and parameters. The
transceiver equipment similar demodulates and possibly decodes and
decrypts, if necessary, any communication signals received from the
wireless communications device 102 transmitting within its cell.
Communication protocols and parameters may vary between different
networks. For example, one network may employ a different
modulation scheme and operate at different frequencies than other
networks.
[0037] The wireless link shown in communication system 100 of FIG.
1 represents one or more different channels, typically different
radio frequency (RF) channels, and associated protocols used
between wireless network 104 and wireless communications device
102. An RF channel is a limited resource that must be conserved,
typically due limits in overall bandwidth and a limited battery
power of the wireless device 102. Those skilled in the art will
appreciate that a wireless network in actual practice may include
hundreds of cells, each served by a station 118, depending upon
desired overall expanse of network coverage. All pertinent
components may be connected by multiple switches and routers (not
shown), controlled by multiple network controllers.
[0038] For all wireless communications devices 102 registered with
a network operator, permanent data (such as the user profile
associated with each device) as well as temporary data (such as the
current location of the device) are stored in the HLR 132. In case
of a voice call to the wireless device 102, the HLR 132 is queried
to determine the current location of the device 102. A Visitor
Location Register (VLR) of MSC 122 is responsible for a group of
location areas and stores the data of those wireless devices that
are currently in its area of responsibility. This includes parts of
the permanent data that have been transmitted from HLR 132 to the
VLR for faster access. However, the VLR of MSC 122 may also assign
and store local data, such as temporary identifications.
Optionally, the VLR of MSC 122 can be enhanced for more efficient
co-ordination of GPRS and non-GPRS services and functionality (e.g.
paging for circuit-switched calls which can be performed more
efficiently via SGSN 126, and combined GPRS and non-GPRS location
updates).
[0039] Serving GPRS Support Node (SGSN) 126 is at the same
hierarchical level as MSC 122 and keeps track of the individual
locations of wireless devices 102. SGSN 126 also performs security
functions and access control. Gateway GPRS Support Node (GGSN) 128
provides internetworking with external packet-switched networks and
is connected with SGSNs (such as SCSN 126) via an IP-based GPRS
backbone network. SGSN 126 performs authentication and cipher
setting procedures based on the same algorithms, keys, and criteria
as in existing GSM. In conventional operation, cell selection may
be performed autonomously by wireless device 102 or by the
transceiver equipment instructing the wireless device to select a
particular cell. The wireless device 102 informs wireless network
104 when it reselects another cell or group of cells, known as a
routing area.
[0040] In order to access GPRS services, the wireless device 102
first makes its presence known to wireless network 104 by
performing what is known as a GPRS "attach". This operation
establishes a logical link between the wireless device 102 and SGSN
126 and makes the wireless device 102 available to receive, for
example, pages via SGSN, notifications of incoming GPRS data, or
SMS messages over GPRS. In order to send and receive GPRS data, the
wireless device 102 assists in activating the packet data address
that it wants to use. This operation makes the wireless device 102
known to GCSN 128; internetworking with external data networks can
thereafter commence. User data may be transferred transparently
between the wireless device 102 and the external data networks
using, for example, encapsulation and tunnelling. Data packets are
equipped with GPRS-specific protocol information and transferred
between wireless device 102 and GGSN 128.
[0041] Those skilled in the art will appreciate that a wireless
network may be connected to other systems, possibly including other
networks, not explicitly shown in FIG. 1. A network will normally
be transmitting at very least some sort of paging and system
information on an ongoing basis, even if there is no actual packet
data exchanged. Although the network consists of many parts, these
parts all work together to result in certain behaviours at the
wireless link.
[0042] FIG. 2 is a detailed block diagram of a preferred wireless
communications device 202. The wireless device 202 is preferably a
two-way communication device having at least voice and advanced
data communication capabilities, including the capability to
communicate with other computer systems. Depending on the
functionality provided by the wireless device 202, it may be
referred to as a data messaging device, a two-way pager, a cellular
telephone with data message capabilities, a wireless Internet
appliance, or a data communications device (with or without
telephony capabilities). The wireless device 202 may communicate
with any one of a plurality of fixed transceiver stations 200
within its geographic coverage area.
[0043] The wireless communications device 202 will normally
incorporate a communication subsystem 211, which includes a
receiver 212, a transmitter 214, and associated components, such as
one or more (preferably embedded or internal) antenna elements 216
and 218, local oscillators (LO's) 213, and a processing module such
as a digital signal processor (DSP) 220. Communication subsystem
211 is analogous to RF transceiver circuitry 108 and antenna 110
shown in FIG. 1. As will be apparent to those skilled in the field
of communications, the particular design of communication subsystem
211 depends on the communication network in which the wireless
device 202 is intended to operate.
[0044] The wireless device 202 may send and receive communication
signals over the network after required network registration or
activation procedures have been completed. Signals received by
antenna 216 through the network are input to receiver 212, which
may perform common receiver functions as signal amplification,
frequency down conversion, filtering, channel selection, and the
like, and, as shown in the example of FIG. 2, analog-to-digital
(A/D) conversion. A/D conversion of a received signal allows more
complex communication functions such as demodulation and decoding
to performed in the DSP 220. In a similar manner, signals to be
transmitted are processed, including modulation and encoding, for
example, by DSP 220. These DSP-processed signals are input to
transmitter 214 for digital-to-analog (D/A) conversion, frequency
up conversion, filtering, amplification and transmission over
communication network via antenna 218. DSP 220 not only processes
communication signals, but also provides for receiver and
transmitter control. For example, the gains applied to
communication signals in receiver 212 and transmitter 214 may be
adaptively controlled through automatic gain control algorithms
implemented in the DSP 220.
[0045] Network access is associated with a subscriber or user of
the wireless device 202, and therefore the wireless device requires
a Subscriber Identity Module or SIM card 262 to be inserted in a
SIM interface 264 in order to operate in the network. SIM 262
includes those features described in relation to FIG. 1. Wireless
device 202 is a battery-powered device so it also includes a
battery interface 254 for receiving one or more rechargeable
batteries 256. Such a battery 256 provides electrical power to most
if not all electrical circuitry in the device 102, and battery
interface provides for a mechanical and electrical connection for
it. The battery interface 254 is coupled to a regulator (not shown)
which provides a regulated voltage V to all of the circuitry.
[0046] Wireless communications device 202 includes a microprocessor
238 (which is one implementation of controller 106 of FIG. 1) which
controls overall operation of wireless device 202. Communication
functions, including at least data and voice communications, are
performed through communication subsystem 211. Microprocessor 238
also interacts with additional device subsystems such as a display
222, a flash memory 224, a random access memory (RAM) 226,
auxiliary input/output (I/O) subsystems 228, a serial port 230, a
keyboard 232, a speaker 234, a microphone 236, a short-range
communications subsystem 240, and any other device subsystems
generally designated at 242. Some of the subsystems shown in FIG. 2
perform communication-related functions, whereas other subsystems
may provide "resident" or on-board functions. Notably, some
subsystems, such as keyboard 232 and display 222, for example, may
be used for both communication-related functions, such as entering
a text message for transmission over a communication network, and
device-resident functions such as a calculator or task list.
Operating system software used by the microprocessor 238 is
preferably stored in a persistent (non-volatile) store such as
flash memory 224, which may alternatively be a read-only memory
(ROM) or similar storage element (not shown). Those skilled in the
art will appreciate that the operating system, specific device
applications, or parts thereof, may be temporarily loaded into a
volatile store such as RAM 226.
[0047] Microprocessor 238, in addition to its operating system
functions, enables execution of software applications on the
wireless device 202. A predetermined set of applications which
control basic device operations, including at least data and voice
communication applications, will normally be installed on the
device 202 during its manufacture. For example, the device may be
pre-loaded with a personal information manager (PIM) having the
ability to organize and manage data items relating to the user's
profile, such as e-mail, calendar events, voice mails,
appointments, and task items. Naturally, one or more memory stores
are available on the device 202 and SIM 256 to facilitate storage
of PIM data items and other information.
[0048] The PIM application preferably has the ability to send and
receive data items via the wireless network. PIM data items may be
seamlessly integrated, synchronized, and updated via the wireless
network, with the wireless device user's corresponding data items
stored and/or associated with a host computer system thereby
creating a mirrored host computer on the wireless device 202 with
respect to such items. This is especially advantageous where the
host computer system is the wireless device user's office computer
system. Additional applications may also be loaded into the memory
store(s) of the wireless communications device 202 through the
wireless network, the auxiliary I/O subsystem 228, the serial port
230, short-range communications subsystem 240, or any other
suitable subsystem 242, and installed by a user in RAM 226 or
preferably a non-volatile store (not shown) for execution by the
microprocessor 238. Such flexibility in application installation
increases the functionality of the wireless device 202 and may
provide enhanced onboard functions, communication-related functions
or both. For example, secure communication applications may enable
electronic commerce functions and other such financial transactions
to be performed using the wireless device 202.
[0049] In a data communication mode, a received signal such as a
text message, an e-mail message, or a web page download will be
processed by communication subsystem 211 and input to
microprocessor 238. Microprocessor 238 will preferably further
process the signal for output to display 222 or alternatively to
auxiliary I/O device 228. A user of the wireless device 202 may
also compose data items, such as email messages, for example, using
keyboard 232 in conjunction with display 222 and possibly auxiliary
I/O device 228. Keyboard 232 is preferably a complete alphanumeric
keyboard and/or telephone-type keypad. These composed items may be
transmitted over a communication network through communication
subsystem 211.
[0050] For voice communications, the overall operation of the
wireless communications device 202 is substantially similar, except
that the received signals would be output to speaker 234 and
signals for transmission would be generated by microphone 236.
Alternative voice or audio I/O subsystems, such as a voice message
recording subsystem, may also be implemented on the wireless device
202. Although voice or audio signal output is preferably
accomplished primarily through speaker 234, display 222 may also be
used to provide an indication of the identity of the calling party,
duration on a voice call, or other voice call related information,
as some examples.
[0051] Serial port 230 in FIG. 2 is normally implemented in a
personal digital assistant (PDA)-type communication device for
which synchronization with a user's desktop computer is a
desirable, albeit optional, component. Serial port 230 enables a
user to set preferences through an external device or software
application and extends the capabilities of wireless device 202 by
providing for information or software downloads to the wireless
device 202 other than through the wireless network. The alternate
download path may, for example, be used to load an encryption key
onto the wireless device 202 through a direct and thus reliable and
trusted connection to thereby provide secure device
communications.
[0052] Short-range communications subsystem 240 of FIG. 2 is an
additional optional component which provides for communication
between mobile station 202 and different systems or devices, which
need not necessarily be similar devices. For example, subsystem 240
may include an infrared device and associated circuits and
components, or a Bluetooth.TM. communication module to provide for
communication with similarly-enabled systems and devices.
Bluetooth.TM. is a trademark of Bluetooth SIG, Inc.
[0053] FIG. 3A is a system diagram of network components which
provide mapping functionality in the wireless communication devices
of FIGS. 1 and 2. To achieve this, a mapping application is also
provided in memory of the wireless communications device for
rendering visual maps in its display. Wireless communications
devices 202 are connected over a mobile carrier network 303 for
communication through a firewall 305 to a relay 307. A request for
map data from any one of the wireless communications devices 202 is
received at relay 307 and passed via a secure channel 309 through
firewall 311 to a corporate enterprise server 313 and corporate
mobile data system (MDS) server 315. The request is then passed via
firewall 317 to a public map server and/or to a public
location-based service (LBS) server 321 which provides
location-based services (LBS) to handle the request. The network
may include a plurality of such map servers and/or LBS servers
where requests are distributed and processed through a load
distributing server. The map/LBS data may be stored on this network
server 321 in a network database 322, or may be stored on a
separate map server and/or LBS server (not shown). Private
corporate data stored on corporate map/LBS server 325 may be added
to the public data via corporate MDS server 315 on the secure
return path to the wireless device 202. Alternatively, where no
corporate servers are provided, the request from the wireless
device 202 may be passed via relay 307 to a public MDS server 327,
which sends the request to the public map/LBS server 321 providing
map data or other local-based service in response to the request.
For greater clarity, it should be understood that the wireless
devices can obtain map data from a "pure" map server offering no
location-based services, from an LBS server offering location-based
services in addition to map content, or from a combination of
servers offering map content and LBS.
[0054] A Maplet data structure is provided that contains all of the
graphic and labelled content associated with a geographic area
(e.g. map features such as restaurants (point features), streets
(line features) or lakes (polygon features)). Maplets are
structured in Layers of Data Entries ("DEntries") identified by a
"Layer ID" to enable data from different sources to be deployed to
the device and meshed for proper rendering. Each DEntry is
representative of one or more artefact or label (or a combination
of both) and includes coordinate information (also referred to as a
"bounding box" or "bounding area") to identify the area covered by
the DEntry and a plurality of data points that together represent
the artefact, feature or label. For example, a DEntry may be used
to represent a street on a city map (or a plurality of streets),
wherein the carious points within the DEntry are separated into
different parts representing various portions of the artefact or
map feature (e.g. portions of the street). A wireless device may
issue a request for the map server to download only those DEntries
that are included within a specified area or hounding box
representing an area of interest that can be represented by, for
example, a pair of bottom left, top right coordinates.
[0055] As depicted in FIG. 3B, the wireless communications device
issues one or more AOI (Area of Interest) requests, DEntry or data
requests and Maplet Index requests to the map server for selective
downloading of map data based on user context. Thus, rather than
transmitting the entire map data for an area in reply to each
request from the device (which burdens the wireless link), local
caching may be used in conjunction with context filtering of map
data on the server. For example, if a user's wireless device is GPS
enabled and the user is traveling in an automobile at 120 km/h
along a freeway then context filtering can by employed to prevent
downloading of map data relating to passing side streets. Or, if
the user is traveling in an airplane at 30,000 feet, then context
filtering can be employed to prevent downloading of map data for
any streets whatsoever. Also, a user's context can be defined, for
example, in terms of occupation, e.g. a user whose occupation is a
transport truck driver can employ context filtering to prevent
downloading of map data for side streets on which the user's truck
is incapable of traveling, or a user whose occupation is to
replenish supplied of soft drink dispensing machines can employ
context filtering to download public map data showing the user's
geographical area of responsibility with irrelevant features such
as lakes and parks filtered out and private map data containing the
location of soft drink dispensing machines superimposed on the
public map data.
[0056] The Maplet Index request results in a Maplet Index (i.e.
only a portion of the Maplet that provides a table of contents of
the map data available within the Maplet rather than the entire
Maplet) being downloaded from the map server to the device, thereby
conserving OTA (Over-the-Air) bandwidth and device memory caching
requirements. The Maplet Index conforms to the same data structure
as a Maplet, but omits the data points. Consequently, the Maplet
Index is small (e.g. 300-400 bytes) relative to the size of a fully
populated Maplet or a conventional bit map, and includes DEntry
bounding boxes and attributes (size, complexity, etc.) for all
artefacts within the Maplet. As the field of view changes (e.g. for
a location-aware device that displays a map while moving), the
device (client) software assesses whether or not it needs to
download additional data from the server. Thus, if the size
attribute or complexity attribute of an artefact that has started
to move into the field of view of the device (but is not yet being
displayed) is not relevant to the viewer's current context, then
the device can choose not to display that portion of the artifact.
On the other hand, if the portion of the artefact is appropriate
for display, then the device accesses its cache to determine
whether the DEntries associated with that portion of the artefact
have already been downloaded, in which case the cached content is
displayed. Otherwise, the device issues a request for the map
server to download all the of the DEntries associated with the
artifact portion.
[0057] By organizing the Maplet data structure in Layers, it is
possible to seamlessly combine and display information obtained
from public and private databases. For example, it is possible for
the device to display an office building at a certain address on a
street (e.g. a 1.sup.st z-order attribute from public database),
adjacent a river (e.g. a 2.sup.nd z-order attribute from public
database), with a superimposed floor plane of the building to show
individual offices (e.g. 11.sup.th z-order attribute from a private
database, accessible through a firewall).
[0058] Referring back to FIG. 3A, within the network having map
server(s) and/or LBS server(s) 321 and database(s) 322 accessible
to it, all of the map data for the entire world is divided and
stored as a grid according to various levels of resolution (zoom),
as set forth below in Table A. Thus, a single A-level Maplet
represents a 0.05.times.0.05 degree grid area; a single B-level
Maplet represents a 0.5.times.0.5 degree grid area; a single
C-level Maplet represents a 5.times.5 degree grid area; a single
D-level Maplet represents a 50.times.50 degree grid area; and a
single E level Maplet represents the entire world in a single
Maplet. It is understood that Table A is only an example of a
particular Maplet grid division; different grid divisions having
finer or coarser granularity may, of courser, be substituted. A
Maplet includes a set of layers, with each layer containing a set
of DEntries, and each DEntry containing a set of data points.
TABLE-US-00001 TABLE A # of Maplets # of Maplets # of Maplets Grid
to cover to cover to cover Level (degrees) the World North America
Europe A 0.05 .times. 0.05 25,920,000 356,000 100,000 B 0.5 .times.
0.5 259,200 6,500 1000 C 5 .times. 5 2,592 96 10 D 50 .times. 50 32
5 5 E World 1 1 1
[0059] As mentioned above, three specific types of requests may be
generated by a wireless communications device (i.e. the
client)--AOI requests, DEntry requests and Maplet Index requests.
The requests may be generated separately or in various
combinations, as discussed in greater detail below. An AOI (area of
interest) request calls for all DEntries in a given area (bounding
box) for a predetermined or selected set of z-order Layers. The AOI
request is usually generated when the device moves to a new area so
as to fetch DEntries for display before the device client knows
what is available in the Maplet. The Maplet Index has the exact
same structure as a Maplet but does not contain complete DEntries
(i.e. the data Points actually representing artifacts and labels
are omitted). Thus, a Maplet Index defines what Layers and DEntries
are available for a given Maplet. A data or DEntry request is a
mechanism to bundle together all of the required Dentries for a
given Maplet.
[0060] Typically, AOI and Maplet Index requests are paired together
in the same message, although they need not be, while DEntry
requests are generated most often. For example, when a wireless
device moves into an area for which no information has been stored
on the device client, the Maplet Index request returns a Maplet
Index that indicates what data the client can specifically request
from the server 321, while the AOI request returns any DEntries
within the area of interest for the specified Layers (if they
exist). In the example requests shown on FIG. 3B, the desired
Maplet is identified within a DEntry request by specifying the
bottom-left Maplet coordinate. In addition, the DEntry request may
include a layer mask so that unwanted Layers are not downloaded, a
DEntry mask so that unwanted data Points are not downloaded, and
zoom values to specify a zoom level for the requested DEntry. Once
the device client has received the requested Maplet Index, the
client typically then issues multiple DEntry requests to ask for
specific DEntries (since the client knows all of the specific
DEntries that are available based on the Maplet Index).
[0061] In this particular implementation, a collection of
20.times.20 A-level Maplets (representing a 1.times.1 degree
square) is compiled into a Maplet Block File (.mbl). An .mbl file
contains a header which specifies the offset and length of each
Maplet in the .mbl file. The same 20.times.20 collection of Maplet
index data is compiled into a Maplet Index file (.mbx). The .mbl
and .mbx file structures are set forth in Tables B and C,
respectively. TABLE-US-00002 TABLE B Address Offset Offset Length
0x000 Maplet #0 Offset Maplet #0 Length (4 bytes) (4 bytes) 0x008
Maplet #1 Offset Maplet #1 Length 0x010 Maplet #2 Offset Maplet #2
Length . . . . . . . . . 0xC78 Maplet #399 Maplet #399 Offset
Length 0xC80 Beginning of Maplet #0 0xC80 + Size of Maplet #0
Beginning of Maplet #1 0xC80 + Size of Maplet #0 + #1 Beginning of
Maplet #2 . . . . . . 0xC80 + .SIGMA. of Size of Beginning of
Maplet #399 Maplets (#0:#398)
[0062] In Table B, the offset of Maplet #0 is 0x0000.sub.--0000
since, in this particular example, the data structure is based on
the assumption that the base address for the actual Maplet data is
0x0000.sub.--0C80. Therefore the absolute address for Maplet #0
data is: Maplet #0 Address=Base Address (0x0000.sub.--0C80)+Maplet
#0 Offset (0x0000.sub.--0000), and additional Maplet addresses are
calculated as: Maplet #(n+1) Offset=Maplet #(n) Offset+Maplet #(n)
Length. If a Maplet has no data or does not exist, the length
parameter is set to zero (0x0000.sub.--0000). TABLE-US-00003 TABLE
C Address Offset Offset (4 bytes) Length (4 bytes) 0x000 Maplet
Index #0 Maplet Index #0 Offset Length 0x008 Maplet Index #1 Maplet
Index #1 Offset Length 0x010 Maplet Index #2 Maplet Index #2 Offset
Length . . . . . . . . . 0xC78 Maplet Index #399 Maplet Index #399
Offset Length 0xC80 Beginning of Maplet Index #0 0xC80 + Size of
Beginning of Maplet Index #1 Maplet Index #0 0xC80 + Size of
Beginning of Maplet Index #2 Maplet Index #0 + #1 . . . . . . 0xC80
+ .SIGMA. of Beginning of Maplet Index #399 Size of Maplet Indices
(#0:#399)
[0063] In Table C, the offset of Maplet Index #0 is
0x0000.sub.--0000 since, according to an exemplary embodiment the
data structure is based on the assumption that the base address for
the actual Maplet index data is 0x0000.sub.--0C80. Therefore, the
absolute address for Maplet Index #0 data is: Maplet Index #0
Address=Base Address (0x0000.sub.--0C80)+Maplet Index #0 Offset
(0x0000.sub.--0000), and additional Maplet index addresses are
calculated as: Maplet Index #(n+1) Offset=Maplet Index #(n)
Offset+Maplet Index #(n) Length. If a Maplet Index has no data or
does not exist, the length parameter is set to zero
(0x0000.sub.--0000).
[0064] FIG. 3C and Table D (below), in combination, illustrate, by
way of example only, a basic Maplet data structure. Generally, as
noted above, the Maplet data structure can be said to include a
Maplet Index (i.e. an index of the DEntries, each of which is
representative of either an artifact or a label or both) together
with data Points for each DEntry that actually form such artifacts
and labels. In this example, each Maplet includes a Map ID (e.g.
0xA1B1C1D1), the # of Layers in the Maplet, and a Layer Entry for
each Layer. The Map ID identifies the data as a valid Maplet, and
according to one alternative, may also be used to identify a
version number for the data. The # of Layers is an integer which
indicates the number of Layers (and therefore Layer Entries) in the
Maplet. Each Layer Entry defines rendering attributes and is
followed by a list of DEntries for each Layer. The above forms a
Maplet Index. For a complete Maplet, each DEntry contains a set of
data Points (referred to herein as oPoints) or Labels). It will be
noted that Layers can have multiple DEntries and the complete list
of DEntries and Points are grouped by Layer and separated by a
Layer Separator (e.g. hex value 0xEEEEEEEE). In this example, each
Layer Entry is 20 bytes long, and a DEntry is 12 bytes long.
However, the number of Layers, number of DEntries per Layer and the
number of Points per DEntry depends on the map data and is
generally variable.
[0065] Table D provides a high "byte-level" description of a Maplet
for this example. TABLE-US-00004 TABLE D Data Quantity Total # of
Bytes Map ID 1 4 bytes # of Layers 1 4 bytes Layer Entries # of 20
bytes .times. (# of Layers) Layers DEntry of a x (# of # of 12
bytes .times. (.SIGMA. of the # Layer DEntries Layers of DEntries
in each in a Layer) + Points for Layer) 4 bytes .times. (.SIGMA. of
the # of DEntry of a Points in each DEntry in Layer each Layer) +
Layer Separator 4 bytes .times. (# of Layers)
[0066] By way of a further example, the wireless network 200
depicted in FIG. 4 can include an applications gateway (AG) 350 for
optimizing data flow for onboard applications such as a mapping
application 500 stored in memory (e.g. stored in a flash memory
224) and executable by the microprocessor 238 of the wireless
device 202.
[0067] As shown in FIG. 4, the wireless network 200 hosts a
plurality of handheld wireless communications devices 202 (such as
the BlackBerry.TM. by Research in Motion Limited) having voice and
data capabilities (for both e-mail and web browsing) as well as a
full QWERTY keyboard. These wireless communications devices 202 can
access Web-based map data on public map servers 400 hosted on the
Internet or other data network 130 via the applications gateway
(AG) 350 which mediates and optimizes data flow between the
wireless network 200 and the data network by performing various
mappings, compressions and optimizations on the data.
[0068] The map server extracts generic map content from a
Geographical Information Systems (GIS) map database (e.g.
Navtech.RTM., TelAtlas.RTM., etc.) at a specified level of
resolution (zoom level). Custom graphics associated with the query,
such as highlighted route, pushpin for current position or street
address, etc. are post-processed and merged by the server with the
generic map content. Relevant screen graphics are then labelled,
and the merged map graphic is compressed and delivered to the
device for display.
[0069] In operation, a user of the wireless communications device
202 uses an input device such as keyboard 232 and/or thumbwheel 233
to cause the microprocessor 238 to open the map application 500
stored in the memory 224. Using the keyboard 232 and thumbwheel
233, the user specifies a map location on the map application 500.
In response to this request/command, the microprocessor 238
instructs the RF transceiver circuitry 211 to transmit the request
over the air through the wireless network 104. The request is
processed by the AG 350 and forwarded into the data network
(Internet) using standard packet-forwarding protocols to one or
more of the public and/or private map servers 400, 410. Accessing a
private map server 410 behind a corporate firewall 420 was
described above with reference to FIG. 3A. Map data downloaded from
these one or more map servers 400, 410 is then forwarded in data
packets through the data network and mapped/optimized by the AS 350
for wireless transmission through the wireless network 104 to the
wireless communications device 202 that originally sent the
request.
[0070] The downloaded map data can be cached locally in RAM 226,
and displayed on the display 222 or graphical user interface (GUI)
of the device after the map application 500 reconstructs or
"stitches together" portions of features or constituent path
segments to generate a reconstructed map feature or path, as will
elaborated below, so that a single instance of the label can be
centrally rendered for the reconstructed feature or path (provided
it does not collide with another label of higher priority). If a
further request is made by the user (or if the user wants a change
in the field of view by zooming or panning), the device will check
whether the data required can be obtained from the local cache (RAM
226). If not, the device issues a new request to the one or more
map servers 400, 410 in the same manner as described above.
[0071] As described earlier, map data can optionally be downloaded
first as a Maplet Index enabling the user to then choose which
DEntries listed in the Index to download in full. Furthermore, as
described earlier, the map application can include
user-configurable context filtering that enables the user to filter
out unwanted map features or artifacts by not downloading specific
DEntries corresponding to those unwanted map features or
artifacts.
[0072] As a variant, the wireless communications device can
optionally include a Global Positioning System (GPS) receiver ("GPS
chip") 550 for providing location-based services (LBS) to the user
in addition to map content. Embedding a GPS chip 550 capable of
receiving and processing signals from UPS satellites enable the GPS
chip to generate latitude and longitude coordinates, thus making
the device "location aware". To obtain local-based services, the
map application within the wireless communications device sends a
request to the map server for information relating to a city,
restaurant, street address, route, etc. If the device is "location
aware", the request would include the current location of the
device.
[0073] In lieu of, or in addition to, GPS coordinates, the location
of the device can be determined using triangulation of signals from
in-range base towers, such as used for Wireless E911. Wireless
Enhanced 911 services enable a cell phone or other wireless device
to be located geographically using radiolocation techniques such as
(i) angle of arrival (AOA) which entails locating the caller at the
point where signals from two towers intersect; (ii) time difference
of arrival (TDOA), which uses multilateration like GPS, except that
the networks determine the time difference and therefore the
distance from each tower; and (iii) location signature, which uses
"fingerprinting" to store and recall patterns (such as multipath)
which mobile phone signals exhibit at different locations in each
cell.
[0074] Operation of the systems described above will now be
described with reference to the method steps depicted in the
flowchart of FIG. 5. As depicted in FIG. 5, this method of
displaying a map on a wireless communications device includes
initial steps of opening the map application on the device (step
600) and specifying an area of interest (AOI) using the map
application (step 602), e.g. specifying a street address,
coordinates of latitude or longitude, or clicking on a location on
a world map, etc. In response to the specifying of an AOI, map data
is then obtained (step 604) for rendering the map to be displayed
on the wireless communications device. For the purposes of this
specification, "obtaining map data" means receiving or downloading
the map data over the air, i.e. over a wireless link, retrieving
the map data from a local cache, or downloading the map data over a
wired connection, or any combination thereof. In other words, as
depicted in FIG. 5, obtaining map data includes steps of
determining whether the data is already cached locally (step 604).
If the data is locally cached, the map data is retrieved from the
cache (step 606). Otherwise, if not all of the map data is cached,
then the map data is downloaded over the air (step 608).
[0075] As depicted in FIG. 5, once the map data is obtained, the
device generates a list of all labels to be rendered (step 610).
Once this label list is created (and preferably sorted into
alphabetical order for more efficient processing), the device
checks to see whether any of the labels are duplicated or redundant
(step 612). If no duplicated (redundant) labels are found in the
label list, the map is then rendered (step 614) without performing
any stitching or reconstruction of paths or features. Rendering of
the map can include a step (not shown) of verifying that the labels
do not interfere with other labels. For example, this step of
verifying that the labels do not interfere with other labels may
involve a step of generating a collision-avoidance array
representative of the map to be rendered for provisionally testing
potential map positions prior to actually rendering the map. This
"virtual rendering" enables the map application to ascertain that
labels do not collide or overlap with other labels for which a map
position has been previously assigned.
[0076] As further depicted in the flowchart of FIG. 5, if
duplicated or redundant labels are found in the label list at step
612, then, for each duplicated label, then the device determines
(step 616) whether the paths (or other map features) match or
connect, e.g. by looking at endpoints of path segments, as will be
elaborated below with reference to FIG. 7B. If the paths or
features do not connect or otherwise fit together, then the map is
rendered without stitching the segments together, i.e. labels are
rendered for each of the segments or constituent elements because
these segments or constituent are disjointed or disconnected and
therefore require separate labelling. On the other hand, if, for
any duplicated labels, the path segments or constituent elements of
the map features connect or match, then the path segments or
constituent elements of the map features are reconstructed
("stitched together") to form a reconstructed path or reconstructed
map feature (step 618). Once the reconstructed path or
reconstructed map feature is generated, the map can be rendered
with a single instance of the map label, preferably centrally
positioned along the entire length of the reconstructed path or
centrally disposed vis-a-vis the reconstructed map feature (step
620). Rendering the map with the single instance of the map label
should involve checking whether the label interferes or overlaps
with any other label for which a label position has been
designated. As noted above, this can be accomplished by generating
a collision-avoidance array representing the map to be rendered and
then populating the array with label positions from highest
priority to lowest, checking that each successive label of
decreasing importance does not collide in the array with any
previously assigned label positions.
[0077] For the purposes of this specification, "label" includes not
only all conventional forms of labels, such as city names, street
names, etc, but also any symbols or icons, such as highway number
icons, or symbols or icons used to denote airports, tourist
information kiosks, campgrounds, ferry crossings, etc. on large
scale (regional) maps or restaurants, hotels, bus stations, etc. on
city maps.
[0078] For the purposes of this specification, "map feature" means
a path, road, street, highway or other route and also includes
features such as a body of water (river, lake, bay, strait, sea,
ocean), an island, a park or other geographical feature that can be
rendered from two or more separate sets of map data (i.e. vectors)
for which individual labels are provided (and which are thus
potentially duplicated upon rendering).
[0079] FIG. 6 schematically depicts the process of reconstructing
("stitching") paths and/or map features in order to efficiently
generate aesthetically-labelled maps for being displayed on
wireless communications devices. By way of overview, map data
(which includes label data) is obtained from a map server in the
form of Data Entries ("D Entries"). Different layers of these D
Entries are used to render features of the same type or class.
Thus, for example, one layer of D Entries may be for lakes, rivers
and bodies of water, while another layer of D Entries may be for
highways, roads and streets. This layered implementation enables
context-filtering of desired or pertinent map data so that only
desired or pertinent features are rendered onscreen.
[0080] In the example depicted in FIG. 6, the map is rendered from
three separate D Entries (or three separate groups of P Entries
from different layers). For the sake of illustration, the three D
Entries (D Entry #1, D Entry #2, and D Entry #3) are rendered
together to constitute the (composite) map. As each D Entry has its
own (independent) label for "Main Street" as well as its own label
for "Windy Lake", simply rendering the map data as a composite map
would unacceptably result in duplication of the labels, as shown in
FIG. 6.
[0081] Even if any duplicated labels are suppressed, the resulting
map, as depicted in FIG. 7, would not be aesthetically pleasing
because only one of the three path labels would appear along its
respective path segment (e.g. the Main Street label would appear,
say, only along the first path segment), which is not necessarily
centered. Similarly, only a single instance of the map feature
label (e.g. Windy Lake) would appear on only one of the elements of
the feature (e.g. the Windy Lake label would appear, say, on only
the first constituent portion of the lake). A corollary problem is
that the label can only be displaced over a limited range
corresponding to the segment or constituent element (if
repositioning is mandated by a collision with another label). Since
the label can only be repositioned over a limited range, the
resulting labelled map is aesthetically compromised.
[0082] These problems can be overcome by stitching or
reconstructing paths (or other map features) to create
reconstructed paths (or reconstructed features), as depicted in
FIG. 8. Since the path segments have duplicated labels and
connecting endpoints, the path segments are stitched/reconstructed
to form a single reconstructed path.
[0083] In one implementation, this reconstruction (stitching) can
be accomplished in the manner described in FIGS. 9A-9C. Similarly,
other map features (such as the lake in FIG. 8) can be
reconstructed, or stitched together, to form a single reconstructed
feature.
[0084] For the reconstructed path, only a single instance of the
label (e.g. "Main Street") is rendered, preferably in a central
position vis-a-vis the path (i.e. the most aesthetic place for the
label). Since the path has been stitched together to form a single
reconstructed path, the label can be displaced anywhere along the
reconstructed path. Therefore, as shown by the dashed-line arrows
in FIG. 8, the label can be displaced over a much greater range
than was previously possible when the label was confined to being
rendered somewhere along the limited range of its original path
segment. In other words, not only can the label be centered
vis-a-vis the "true" (from the viewer's perspective) center of the
reconstructed path or feature, but the label can also be displaced
substantially to avoid collisions with other labels.
[0085] Likewise, for the reconstructed map feature (in this
example, the lake), only a single instance of the label (e.g.
"Windy Lake") is rendered, preferably in, a central, prominent
location vis-a-vis the feature, provided it does not collide or
interfere with another pre-existing or higher-priority label.
Furthermore, because of the reconstruction of the feature, the
feature is no longer composed of constituent parts for the purposes
of labelling. Accordingly, the label can be displaced over the
entire range of the feature, not just over the constituent part
with which the label was originally associated. This provides much
more leeway in finding a suitable position for a label on the map,
i.e. a label position that does not collide or interfere with any
other label. In order words, this stitching technique enables
labels to be rendered in preferred positions (e.g. centrally,
prominently, aesthetically, etc.) while providing maximal leeway
for displacing the label in the event that it collides with another
(pre-existing or higher-priority) label.
[0086] FIG. 9A schematically depicts the generation of a label list
700, in accordance with one implementation of present technology,
for determining whether any labels are duplicated in a given set of
D Entries that are to be used to render the map. The label list
700, in this implementation, is generated by the map application
500 using label data received wirelessly by the wireless
communications device 202.
[0087] In the example shown in FIG. 9A, the label list 700 includes
the list of label names itself (i.e. a field for storing the name
of each label instance), a link field (indicating how, if at all,
the label can be linked to any duplicate labels), a vector field
(indicating directionality of map data stored in vector format) and
a flag field (indicating whether the data vector needs to be
reversed to concord with the directionality of a vector of the same
label). Although each of these four fields of the label list is
described in greater detail below, it should be understood that the
details of this label list are presented solely for the purposes of
illustration. Persons of ordinary skill in the art will appreciate
that other implementations of label lists or equivalent algorithms
can be used to determine label redundancy and whether endpoints of
the paths or other non-path features of any redundant labels
match.
[0088] In the example presented in FIG. 9A, the label list 700
includes path labels "First Avenue", "Main Street", and "Second
Avenue" as well as any non-path feature labels, i.e. "Windy Lake".
As shown, multiple instances of each label appear in the label list
700, representing each instance that one of the D Entries used to
render the map carries that particular label. Thus, in this
example, the label "Main Street" is listed three times in the label
list because each of the D Entries used to create the map contains
its own instance of the label "Main Street". Likewise, since each
of the three D Entries contains the non-path feature label "Windy
Lake", this label is listed three times in the label list.
Preferably, the label list is sorted alphabetically to streamline
the algorithm that searches for redundancies and performs the
linking.
[0089] In the example depicted in FIG. 9A, the label list 700
includes a link field or link parameter that indicates for each
label entry (each listed instance of each label) what its
relationship is with a previous or subsequent label of the same
name. Linking of labels can be accomplished using a standard
linked-list construct for objects, which is well known in the art.
If a label appears only once in the label, i.e. has merely a single
instance, then it cannot be linked to another label, and therefore
its link parameter, or link field, is simply indicated as "None".
Thus, returning to the specific example presented in FIG. 9A, the
path label "First Avenue" appears only once, and therefore its link
parameter is "None". The same holds for Second Avenue, which
appears only once. Its link parameter is thus also designated as
"None."
[0090] Unlike First Avenue and Second, the path label "Main Street"
appears three times, and thus its link parameters need to
determined. Determining link parameters (or link status) can be
accomplished by comparing endpoints of each link segment, as
depicted in FIG. 9B. As shown in FIG. 95, the endpoints (x1,y1) of
the first path segment of Main Street are compared with the
endpoints (x2,y2) of the second segment of Main Street. If the
endpoints (x,y coordinates) are equal (or at least match within a
predetermined tolerance), then the segments are eligible to be
stitched together. Accordingly, the link parameter/status is
updated to reflect the concordance of the endpoints of the path
segments. In this example, the first instance of the Main Street
label shows that the link parameter is "Next" (meaning that the
segment with this label connects to the segment associated with the
next label in the list).
[0091] As depicted in FIG. 9B, the endpoints (x3,y3) of the second
segment of path label "Main Street" are compared with the endpoints
(x4,y4) of the third segment of "Main Street" to determine whether
these endpoint coordinates coincide. If the endpoints coincide (or
match within the tolerance), as they do in this example, the link
parameter is updated to indicate that the third label is linked to
the "previous" label, i.e. the second label. Using this linked-list
construct, the relationships between the first Main Street label
and the second Main Street label and between the second Main Street
label and the third Main Street label are defined. In this example,
the first Main Street label is linked to the next label, i.e. the
second Main Street label (and, conversely, the second Main Street
label is linked to the previous Main Street label). The third Main
Street label is linked to the previous Main Street label as well
(i.e. to the second Main Street label) As a result, all three
labels are linked together, meaning that the three path segments
can be stitched together.
[0092] Likewise, the label list also accounts for linkage
relationships between non-path map features such as the lake shown
in FIGS. 6-8. Its label "Windy Lake" appears in each D Entry and
thus three instances of this label appear in the label list. Again,
by comparing endpoints or perimeter points, the constituent parts
of the lake can be compared to see whether they match or align. If
so, the link fields for each Windy Lake entry can be updated as was
done for Main Street.
[0093] As further depicted in FIG. 9B, the label list 700 can
include a vector field and a flag field. The map data is stored in
vector format, allowing the vectors (data) to be packaged in small
"chunks" to facilitate OTA transmission and rendering. If the
bounding box of each "chunk" of data, or D Entry, is small then it
is quicker to intersect its bounding box with the screen's bounding
box to determine if it needs to be rendered (and
requested/transmitted if it not already cached client-side).
Chunking up the data into small packages or D Entries, however,
means that paths and other map features (each having their own
labels) will likely extend into more than one D Entry. The
foregoing technique effectively reconstructs the paths (or
features) by checking whether the endpoints of path segments (or
whether the constituent parts of features) coincide or fit
together. A further problem that arising with the D Entries being
in vector format is that the directionality of one segment of a
path (or feature) could be opposite to that of another segment even
if their respective endpoints coincide. Prior to stitching these
segments (or constituent parts) together, then, it is preferable to
assess the directionality of the vectors defining the segments (or
constituent parts). This can be accomplished using a unit vector
notation such as a presented, by way of example only, in FIG. 9A.
In this example, the First Avenue label is rendered using a unit
vector that runs vertically download (in the y-direction) without
any horizontal component (x=0). Thus, the vector is denoted as
(0,-1). The magnitude of the vector is not relevant, only
direction. Comparison of vector directionality is depicted, again
by way of example only, in FIG. 9C which shows the three segments
of the path Main Street and their associated vectors. Assuming that
the first segment of Main Street has unit vector (1, -1), that the
second segment has unit vector (1,0) and that the third segment has
unit vector (-1,0), then it is observed that the second and third
segments have opposite directions, as shown in FIG. 9C.
Accordingly, this inconsistency in the directionality of two
contiguous segments that are eligible to be conjoined or stitched
together for the purposes of feature reconstruction is flagged in
label list 700. The flag indicates that the third segment of Main
Street needs to have the direction of its vector reversed. Once all
vectors have been aligned by reversing any inconsistent segments of
the path, the three segments can be "stitched" or "spliced"
together to generate the contiguous, reconstructed path.
[0094] Optionally, when the reconstructed path is generated, the
length of each constituent path segment and/or the total length of
the reconstructed path are stored. These values can be used to
determine an initial starting point for centering each label
vis-a-vis the midpoint of the reconstructed path. Knowledge of
these values also facilitates repositioning of the label when a
potential label collision is detected or foreseen. These values can
be stored as further fields of the label list 700. Labels can thus
be rendered, or virtually rendered, with reference to the center of
the reconstructed path, which is the preferred technique.
Alternatively, labels can be rendered (or repositioned in the
virtual rendering process) by virtually rendering a label along a
center of a middle segment (or the segment closest to the middle of
the onscreen bounding box) and then, if all of the label does not
fit along that segment, checking whether the segment is spliced to
a further segment (i.e. checking whether a reconstructed path
exists for that label).
[0095] Similarly, when reconstructing non-path features (i.e.
features that are not lines but rather polygons), other dimensions
such as, for example, the average horizontal width of the polygon
feature, can be stored for each of the constituent elements of the
non-path map feature and for the reconstructed map feature, also
for the purposes of facilitating centered labelling of the
reconstructed feature.
[0096] The label list 700 depicted in FIG. 9A can be implemented
using a labelPath object created for the path, containing the path
data, the label and any other information used to render the label
on the map. Every labelPath object would then be placed into a list
sorted alphabetically according to the label associated with each
path. When each labelPath object is added to the list, a check is
performed to see if there are any other labelPath objects whose
labels are identical to the label of the path being added. If other
labelPath objects are found with identical labels, the endpoints
are compared and, if any match, then the labelPath objects are
associated with each other using a standard linked-list construct,
as alluded to above.
[0097] FIG. 10 is a screenshot of a street map of downtown Ottawa,
Canada without stitching (reconstruction) of paths. As shown, many
of the street labels are not centered onscreen. Some egregious
examples are "Queen St", "Albert St" and "Nepean St" which are far
from being properly centered onscreen. In contrast, FIG. 11 is a
screenshot of a street map of downtown Ottawa, Canada with
stitching (reconstruction) of paths. The labels on this map are
centered vis-a-vis their respective streets. Note, in particular,
how the path labels "Queen St", "Albert St" and "Nepean St" are
centrally located by first stitching the path segments constituting
the entire path. Some repositioning (off-centering) may, of course,
prove to be inevitable as a consequence of having to avoid
collisions with other labels. A collision-avoidance algorithm will
attempt to place the label centrally (at a midpoint of the path),
if possible, but will then reposition the label, if necessary, to
avoid collisions with other labels onscreen.
[0098] The foregoing method steps can be implemented as coded
instructions in a computer program product. In other words, the
computer program product is a computer-readable medium upon which
software code is recorded to perform the foregoing steps when the
computer program product is loaded into memory and executed on the
microprocessor of the wireless communications device.
[0099] This new technology has been described in terms of specific
implementations and configurations which are intended to be
exemplary only. The scope of the exclusive right sought by the
Applicant is therefore intended to be limited solely by the
appended claims.
* * * * *