U.S. patent application number 17/739064 was filed with the patent office on 2022-09-01 for time-of-flight sensor with structured light illuminator.
The applicant listed for this patent is Waymo LLC. Invention is credited to Brendan Hermalyn, Alexander McCauley, Caner Onal, David Schleuning, Simon Verghese, Brandyn White, Ury Zhilinsky.
Application Number | 20220276384 17/739064 |
Document ID | / |
Family ID | 1000006322230 |
Filed Date | 2022-09-01 |
United States Patent
Application |
20220276384 |
Kind Code |
A1 |
Onal; Caner ; et
al. |
September 1, 2022 |
Time-of-Flight Sensor with Structured Light Illuminator
Abstract
The present disclosure relates to systems and methods that
provide information about a scene based on a time-of-flight (ToF)
sensor and a structured light pattern. In an example embodiment, a
sensor system could include at least one ToF sensor configured to
receive light from a scene. The sensor system could also include at
least one light source configured to emit a structured light
pattern and a controller that carries out operations. The
operations include causing the at least one light source to
illuminate at least a portion of the scene with the structured
light pattern and causing the at least one ToF sensor to provide
information indicative of a depth map of the scene based on the
structured light pattern.
Inventors: |
Onal; Caner; (Palo Alto,
CA) ; Schleuning; David; (Piedmont, CA) ;
Hermalyn; Brendan; (San Francisco, CA) ; Verghese;
Simon; (Mountain View, CA) ; McCauley; Alexander;
(Sunnyvale, CA) ; White; Brandyn; (Mountain View,
CA) ; Zhilinsky; Ury; (Sunnyvale, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Waymo LLC |
Mountain View |
CA |
US |
|
|
Family ID: |
1000006322230 |
Appl. No.: |
17/739064 |
Filed: |
May 6, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16177626 |
Nov 1, 2018 |
11353588 |
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17739064 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 7/497 20130101;
G01S 17/89 20130101; G01S 7/4865 20130101; G01S 17/08 20130101;
G01S 17/931 20200101; G01S 7/4808 20130101; G01S 7/4817 20130101;
G06T 7/521 20170101 |
International
Class: |
G01S 17/89 20060101
G01S017/89; G06T 7/521 20060101 G06T007/521; G01S 7/497 20060101
G01S007/497; G01S 7/481 20060101 G01S007/481; G01S 7/48 20060101
G01S007/48; G01S 7/4865 20060101 G01S007/4865; G01S 17/08 20060101
G01S017/08; G01S 17/931 20060101 G01S017/931 |
Claims
1. A sensor system comprising: at least one time-of-flight (ToF)
sensor configured to receive light from a scene; at least one light
source configured to emit a structured light pattern; and a
controller that carries out operations, the operations comprising:
dynamically adjusting the structured light pattern based on one or
more retroreflective regions in the scene; causing the at least one
light source to illuminate at least a portion of the scene with the
structured light pattern; and causing the at least one ToF sensor
to provide time of flight information indicative of a depth map of
the scene based on the structured light pattern.
2. The sensor system of claim 1, wherein dynamically adjusting the
structured light pattern comprises lowering illumination levels for
portions of the scene where the one or more retroreflector regions
are present.
3. The sensor system of claim 1, wherein the at least one ToF
sensor comprises a plurality of complementary metal-oxide
semiconductor (CMOS) or charge-coupled device (CCD) photosensitive
elements.
4. The sensor system of claim 1, wherein the structured light
pattern comprises at least one of: a predetermined spatial
distribution of light, a predetermined temporal distribution of
light, or a predetermined spectral distribution of light.
5. The sensor system of claim 1, wherein the structured light
pattern comprises at least one of: a predetermined light pulse
repetition rate, a predetermined light pulse duration, a
predetermined light pulse intensity, or a predetermined light pulse
duty cycle.
6. The sensor system of claim 1, wherein the at least one light
source comprises at least one of: a laser diode, a light-emitting
diode, a plasma light source, a strobe light, a solid-state laser,
or a fiber laser.
7. The sensor system of claim 1, wherein dynamically adjusting the
structured light pattern comprises selecting a desired structured
light pattern from among a plurality of possible structured light
patterns, wherein causing the at least one light source to
illuminate at least a portion of the scene with the structured
light pattern comprises illuminating the portion of the scene
according to the desired structured light pattern.
8. The sensor system of claim 1, further comprising an imaging
sensor, wherein the imaging sensor comprises a plurality of
photosensitive elements, wherein the plurality of photosensitive
elements comprises at least one million photosensitive elements,
wherein the operations further comprise causing the imaging sensor
to provide information indicative of an image of the scene based on
the structured light pattern.
9. The sensor system of claim 8, wherein the operations further
comprise determining a high-resolution depth map of the scene based
on the depth map of the scene and the image of the scene.
10. The sensor system of claim 8, wherein the at least one ToF
sensor, the imaging sensor, and the at least one light source are
coupled to a common substrate.
11. The sensor system of claim 1, wherein the operations further
comprise determining at least one inference about the scene based
on the depth map of the scene.
12. The sensor system of claim 11, wherein the at least one
inference comprises information about objects in an environment of
a vehicle or an operating context of the vehicle.
13. The sensor system of claim 11, wherein the controller comprises
at least one deep neural network, wherein the determining the at
least one inference is performed by the at least one deep neural
network.
14. A system comprising: a plurality of sensor systems configured
to be coupled to a vehicle, wherein each sensor system comprises:
at least one time-of-flight (ToF) sensor; at least one imaging
sensor, wherein the at least one ToF sensor and the at least one
imaging sensor are configured to receive light from a scene; at
least one light source configured to emit a structured light
pattern; and a controller that carries out operations, the
operations comprising: dynamically adjusting the structured light
pattern based on one or more retroreflective regions in the scene;
causing the at least one light source to illuminate at least a
portion of the scene with the structured light pattern; causing the
at least one ToF sensor to provide time of flight information
indicative of a depth map of the scene based on the structured
light pattern; and causing the imaging sensor to provide
information indicative of an image of the scene based on the
structured light pattern.
15. The system of claim 14, wherein the operations further comprise
determining a high-resolution depth map of the scene based on the
depth map of the scene and the image of the scene.
16. The system of claim 14, wherein at least one of the sensor
systems comprises at least one ToF sensor and at least one imaging
sensor in a common housing.
17. A method comprising: dynamically adjusting a structured light
pattern based on one or more retroreflective regions in a scene;
causing at least one light source to illuminate the scene with the
structured light pattern; receiving, from a time-of-flight (ToF)
sensor, time of flight information about the scene based on the
structured light pattern; determining a depth map of the scene
based on the received information; and determining at least one
inference about the scene based on the depth map of the scene.
18. The method of claim 17, wherein the at least one inference
comprises information about objects in an environment of a vehicle
or an operating context of the vehicle.
19. The method of claim 17, wherein dynamically adjusting the
structured light pattern comprises selecting a desired structured
light pattern from among a plurality of possible structured light
patterns, wherein causing the at least one light source to
illuminate the scene with the structured light pattern comprises
illuminating the scene according to the desired structured light
pattern.
20. The method of claim 17, wherein dynamically adjusting the
structured light pattern further comprises adjusting the structured
light pattern based on an amount of ambient light or a time of day.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation of U.S. patent
application Ser. No. 16/177,626, filed Nov. 1, 2018, the content of
which is herewith incorporated by reference.
BACKGROUND
[0002] Time-of-Flight (ToF) sensors typically provide
low-resolution depth information about a scene, but can be subject
to stray light "blooming" and/or provide inaccurate depth
information when imaging highly reflective or highly absorbing
materials.
[0003] Structured light can include light emitted according to a
desired or predetermined illumination pattern and/or illumination
schedule. Some light sources may be configured to illuminate a
scene with structured light.
SUMMARY
[0004] The present disclosure beneficially combines aspects of ToF
sensors and structured light to provide more accurate,
higher-resolution depth information.
[0005] In a first aspect, a sensor system is provided. The sensor
system includes at least one time-of-flight (ToF) sensor configured
to receive light from a scene. The sensor system also includes at
least one light source configured to emit a structured light
pattern. Furthermore, the sensor system includes a controller that
carries out operations. The operations include causing the at least
one light source to illuminate at least a portion of the scene with
the structured light pattern. The operations also include causing
the at least one ToF sensor to provide information indicative of a
depth map of the scene based on the structured light pattern.
[0006] In a second aspect, a system is provided. The system
includes a plurality of sensor systems configured to be coupled to
a vehicle. Each sensor system includes at least one time-of-flight
(ToF) sensor and at least one imaging sensor. The at least one ToF
sensor and the at least one imaging sensor are configured to
receive light from a scene. Each sensor system also includes at
least one light source configured to emit a structured light
pattern and a controller that carries out operations. The
operations include causing the at least one light source to
illuminate at least a portion of the scene with the structured
light pattern. The operations also include causing the at least one
ToF sensor to provide information indicative of a depth map of the
scene based on the structured light pattern. The operations
additionally include causing the imaging sensor to provide
information indicative of an image of the scene based on the
structured light pattern.
[0007] In a third aspect, a method is provided. The method includes
causing at least one light source to illuminate a scene with a
structured light pattern. The method additionally includes
receiving, from a time-of-flight (ToF) sensor, information about
the scene based on the structured light pattern. The method also
includes determining a depth map of the scene based on the received
information. The method yet further includes determining at least
one inference about the scene based on the depth map of the
scene.
[0008] In a fourth aspect, a method is provided. The method
includes providing prior information. The prior information
includes three-dimensional information of a scene. The method
includes causing at least one light source to illuminate the scene
with a structured light pattern. The method also includes causing
the at least one ToF sensor to provide time of flight information
indicative of a depth map of the scene based on the structured
light pattern.
[0009] Other aspects, embodiments, and implementations will become
apparent to those of ordinary skill in the art by reading the
following detailed description, with reference where appropriate to
the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0010] FIG. 1 illustrates a system, according to an example
embodiment.
[0011] FIG. 2 illustrates an operating scenario of a system,
according to example embodiments.
[0012] FIG. 3A illustrates a vehicle, according to an example
embodiment.
[0013] FIG. 3B illustrates a sensor unit, according to an example
embodiment.
[0014] FIG. 3C illustrates a light source, according to an example
embodiment.
[0015] FIG. 4A illustrates a sensing scenario, according to an
example embodiment.
[0016] FIG. 4B illustrates a sensing scenario, according to an
example embodiment.
[0017] FIG. 4C illustrates various structured light patterns,
according to example embodiments.
[0018] FIG. 4D illustrates a structured light pattern, according to
an example embodiment.
[0019] FIG. 5 illustrates a method, according to an example
embodiment.
[0020] FIG. 6A illustrates a sensing scenario, according to an
example embodiment.
[0021] FIG. 6B illustrates a sensing scenario, according to an
example embodiment.
[0022] FIG. 7 illustrates a method 700, according to an example
embodiment.
DETAILED DESCRIPTION
[0023] Example methods, devices, and systems are described herein.
It should be understood that the words "example" and "exemplary"
are used herein to mean "serving as an example, instance, or
illustration." Any embodiment or feature described herein as being
an "example" or "exemplary" is not necessarily to be construed as
preferred or advantageous over other embodiments or features. Other
embodiments can be utilized, and other changes can be made, without
departing from the scope of the subject matter presented
herein.
[0024] Thus, the example embodiments described herein are not meant
to be limiting. Aspects of the present disclosure, as generally
described herein, and illustrated in the figures, can be arranged,
substituted, combined, separated, and designed in a wide variety of
different configurations, all of which are contemplated herein.
[0025] Further, unless context suggests otherwise, the features
illustrated in each of the figures may be used in combination with
one another. Thus, the figures should be generally viewed as
component aspects of one or more overall embodiments, with the
understanding that not all illustrated features are necessary for
each embodiment.
I. Overview
[0026] Imaging sensors typically provide high quality,
high-resolution, two-dimensional images of a scene, but do not
typically provide independent depth information. Time-of-Flight
(ToF) sensors typically provide low-resolution depth information
about a scene, but can be subject to artifacts such as image
blooming in the presence of highly reflective objects or inaccurate
depth measurements in the presence of mixed scenes with reflective
and absorptive objects. The present disclosure beneficially
combines the desirable aspects of both types of sensors to provide
more accurate, higher-resolution depth information.
[0027] In some examples, blooming can occur when a given sensor
pixel absorbs enough photons such that the number of
photo-generated charge carriers exceeds a full well capacity (FWC).
In such scenarios, upon reaching FWC, excess charge carriers can
"overflow" into neighboring sensor pixels, producing a smearing or
blurring effect, which may reduce image quality and/or reduce
confidence in depth information.
[0028] A hybrid imaging system could include: 1) at least one ToF
sensor; 2) an optional imaging sensor; 3) at least one light source
for illuminating the scene with structured light using continuous
wave (CW), pulsed, or aperiodic illumination; and 4) a controller,
which may include a computer, a processor, and/or a Deep Neural
Net. The ToF sensor and the imaging sensor may be spatially
registered to one another and may utilize overlapping portions of
the same optical path. For example, the ToF sensor and the imaging
sensor could be spatially registered to one another such that they
have a similar (e.g., roughly identical) field of view and their
relative position and orientation could be known and/or fixed with
respect to one other.
[0029] Each sensor unit of a plurality of sensor units of such a
hybrid imaging system could be mounted on each side (or corner) of
a vehicle. Respective sensor units could also be mounted in one or
more spinning platforms at various locations on the vehicle. In an
example embodiment, each sensor unit may include a 180 degree field
of view of a scene around the vehicle. In some embodiments, sensor
units could be positioned on the vehicle so as to have partially
overlapping fields of view of the environment around the
vehicle.
[0030] In an example embodiment, to avoid blooming or other depth
information artifacts, a plurality of ToF sensors could be
associated with one or more image sensors in a given sensor unit.
The respective ToF sensors could be spread out (e.g., spaced apart
by 10 cm or more) so as to reduce the effects of blooming from
specular reflections and other bright light sources. In some
embodiments, the ToF sensors could be operated between 10-100 MHz,
however other operating frequencies are contemplated and possible.
In some embodiments, the operating frequency of the respective ToF
sensor may be adjusted based on a desired maximum depth sensing
range. For instance, a ToF sensor could be operated at 20 MHz for a
desired depth sensing range (e.g., unambiguous range) of
approximately 7.5 meters. In some embodiments, the ToF sensor could
have a maximum desired depth sensing range of 100 meters or
more.
[0031] In some embodiments, the ToF sensor could include CMOS or
CCD photo-sensitive elements (e.g., silicon PIN diodes). However,
other types of ToF sensors and ToF sensor elements are
contemplated. In some cases, the ToF sensor could be operated using
various phase shift modes (e.g., a 2x or 4x phase shift).
[0032] In some embodiments, the imaging sensor could include an RGB
imaging sensor, such as a megapixel-type camera sensor. The imaging
sensor could include a plurality of CMOS or CCD photo-sensitive
elements.
[0033] In some examples, one or more light sources could be used to
illuminate the scene (or respective portions of the scene). In such
scenarios, the light sources could be modulated to provide a
predetermined light pulse (or series of light pulses) that could be
used in conjunction with the ToF sensor to provide depth
information. Additionally or alternatively, the series of light
pulses (e.g., a pulse repetition rate, a pulse duration, and/or a
duty cycle) could be selected so as to provide a desired exposure
for the imaging sensor.
[0034] The one or more light sources could include a light strip
that is disposed along a portion of the vehicle. Additionally or
alternatively, the one or more light sources could include a grid
of light panels, each segment of which could individually provide
different light pulses. Yet further, the one or more light sources
could provide one or more light beams that can be moved in a
point-wise and/or scanning fashion.
[0035] The one or more light sources could be operated in CW and/or
in pulsed (e.g., sine wave, sawtooth, or square wave) operation
mode. Without limitation, the one or more light sources could
include at least one of: a laser diode, a light-emitting diode, a
plasma light source, a strobe, a solid-state laser, a fiber laser,
or another type of light source. The one or more light sources
could be configured to emit light in the infrared wavelength range
(e.g., 850, 905, 940, and/or 1550 nanometers). In some embodiments,
multiple illumination light wavelengths could be used to
disambiguate between multiple light sources, etc. Additionally or
alternatively, the illumination wavelength may be adjusted based on
an amount of ambient light in the environment and/or a time of
day.
[0036] In another example embodiment, the one or more light sources
could emit a structured light pattern into the environment. The
structured light pattern could provide improved registration and/or
resistance to blooming effects. As an example, the structured light
pattern could be formed by transmitting light through a diffractive
optic element. In another embodiment, a laser light pattern (e.g.,
random laser speckle or predetermined laser light pattern) could be
used to provide the structured light pattern. In yet further
embodiments, a deformable or adjustable reflective, diffractive, or
refractive surface (e.g., a micromirror array) could be used to
provide the structured light pattern and/or to shift the pattern
with respect to the scene.
[0037] Additionally or alternatively, the one or more light sources
could be configured to emit one or more classes of structured light
patterns. For instance, the classes of structured light patterns
could include one or more spatial classes, where some regions of a
field of view are illuminated (or not illuminated) according to a
predetermined spatial light pattern. Other classes of structured
light patterns could include temporal classes, where various
regions of a field of view are illuminated at different times
according to a predetermined temporal illumination schedule. Yet
other classes of structured light could include spectral classes,
where various regions of a field of view are illuminated with
different wavelengths--or wavebands--of light according to a
predetermined spectral illumination pattern. However, other ways to
form a structured light pattern are possible and contemplated
herein.
[0038] In some embodiments, the structured light pattern could be
used to disambiguate spatial locations within a scene. For example,
the structured light pattern could include circular and/or
oval-shaped light "spots". Each spot could have a different shape
or orientation (e.g., rotation, spatial extent, radius of
curvature, elongation, etc.) based on, for example, an emission
angle of light through the diffractive optic element or a spatial
position in the scene with respect to the light source. In some
embodiments, a predetermined astigmatism of the optical element
could be utilized to disambiguate between light spots in the
structured light pattern.
[0039] The controller could be operable to combine outputs of the
respective sensors (e.g., using sensor fusion) and/or make
inferences about the three-dimensional scene around the vehicle.
For example, the controller could make inferences to provide a
grayscale or color-intensity map of the vehicle's surroundings. The
inferences may additionally or alternatively provide information
about objects in the vehicle's environment. In an example
embodiment, the object information could be provided at a refresh
rate of 60 or 120 Hz. However, other refresh rates are possible and
contemplated.
[0040] In an example embodiment, the system could include one or
more deep neural networks. The deep neural networks(s) could be
utilized to provide the inferences based on training data and/or an
operating context of the vehicle. In some cases, the low-resolution
depth information and the image information may be provided to the
deep neural network. Subsequently, the deep neural network could
make inferences based on the received information and/or provide
output depth maps (e.g., point clouds) at a high-resolution.
[0041] In some embodiments, two or more of: the ToF sensor, the
image sensor, the light source, and the controller could be coupled
to the same substrate. That is, the system could include a
monolithic chip or substrate so as to provide a smaller sensor
package and/or provide other performance improvements.
II. Example Systems
[0042] FIG. 1 illustrates a system 100, according to an example
embodiment. The system 100 includes at least one Time-of-Flight
(ToF) sensor 110, or ToF camera. In an example embodiment, the at
least one ToF sensor 110 could include a plurality of complementary
metal-oxide semiconductor (CMOS) or charge-coupled device (CCD)
photosensitive elements (e.g., silicon PIN diodes). Other types of
photosensitive elements could be utilized by the ToF sensor
110.
[0043] In some embodiments, the at least one ToF sensor 110 could
be configured to actively estimate distances to environmental
features in its respective field of view based on the speed of
light. For instance, the ToF sensor 110 could measure the
time-of-flight of a light signal (e.g., a light pulse) upon
traveling between a light source (e.g., light source 130) and an
object in the scene. Based on estimating the time-of-flight of
light pulses from a plurality of locations within a scene, a range
image or depth map can be built up based on the ToF sensor's field
of view. While the distance resolution can be 1 centimeter or less,
the lateral resolution can be low as compared to standard 2D
imaging cameras.
[0044] In some embodiments, the ToF sensor 110 can obtain images at
120 Hz or faster. Without limitation, the ToF sensor 110 could
include a range-gated imager or a direct time-of-flight imager.
[0045] Optionally, the system 100 may also include at least one
imaging sensor 120. In an example embodiment, the imaging sensor
120 could include a plurality of photosensitive elements. In such a
scenario, the plurality of photosensitive elements could include at
least one million photosensitive elements. The at least one ToF
sensor 110 and the at least one imaging sensor 120 are configured
to receive light from a scene.
[0046] The system 100 also includes at least one light source 130.
In an example embodiment, the at least one light source 130 could
include at least one of: a laser diode, a light-emitting diode, a
plasma light source, a strobe light, a solid-state laser, or a
fiber laser. Other types of light sources are possible and
contemplated in the present disclosure. The at least one light
source 130 could include a light strip (e.g., disposed along a
portion of a vehicle). Additionally or alternatively, the at least
one light source 130 could include, for example, a grid of light
panels, each segment of which could individually provide different
light pulses. Yet further, the at least one light source 130 could
provide one or more light beams that can be moved in a point-wise
and/or scanning fashion. The at least one light source 130 could be
operated in a continuous wave (CW) mode and/or in a pulsed (e.g.,
sine wave, sawtooth, or square wave) operation mode.
[0047] In an example embodiment, the at least one light source 130
could be configured to emit infrared light (e.g., 900-1600
nanometers). However, other wavelengths of light are possible and
contemplated.
[0048] In some embodiments, the at least one light source 130 could
be configured to emit light into the environment according to a
desired structured light pattern. The structured light pattern
could include, for example, aperiodic and/or inhomogeneous
illumination of the environment by the at least one light source
130. For example, the desired structured light pattern could
include a checkerboard pattern, a dot pattern, a stripe pattern, a
speckle pattern, or another predetermined light pattern.
Additionally or alternatively, in some embodiments, pseudorandom
light patterns are possible and contemplated. The desired
structured light pattern could be defined by light pulses, or
shots, emitted along a predetermined pointing angle and/or within a
predetermined field of view. In some embodiments, the light pulses
could be provided at different temporal and/or spatial/angular
densities based on the desired structured light pattern.
[0049] The at least one light source 130 and the ToF sensor 110
could be temporally synchronized. That is, a trigger signal to
cause the light source 130 to emit light could also be provided to
the ToF imager 110 as a temporal reference signal. As such, the ToF
sensor 110 may have information about a time of the actual onset of
the light emitted from the light source 130. Additionally or
alternatively, the ToF sensor 110 could be calibrated based on a
reference target at a known distance from the ToF sensor 110.
[0050] In scenarios with multiple light sources and/or multiple ToF
imagers, the multiple light sources could utilize time multiplexing
or other types of signal multiplexing (e.g., frequency or code
multiplexing) so as to disambiguate time-of-flight information
(light pulses) obtained by a given ToF imager from the various
light sources.
[0051] In some embodiments, the at least one light source 130 could
be configured to emit light into an environment along a plurality
of emission vectors toward various target locations so as to
provide a desired resolution. In such scenarios, the at least one
light source 130 could be operable to emit light along the
plurality of emission vectors such that the emitted light interacts
with an external environment of the system 100.
[0052] In an example embodiment, the respective emission vectors
could include an azimuthal angle and/or an elevation angle (and/or
corresponding angular ranges) with respect to a heading or location
of a vehicle (e.g., vehicle 300 as illustrated and described with
reference to FIG. 3A). In some embodiments, light emitted by the at
least one light source 130 could be directed along the respective
emission vectors by adjusting a movable mount and/or a movable
mirror.
[0053] For example, the at least one light source 130 could emit
light toward a movable mirror. By adjusting an orientation of the
movable mirror, the emission vector of the light could be
controllably modified. It will be understood that many different
physical and optical techniques may be used to direct light toward
a given target location. All such physical and optical techniques
for adjusting an emission vector of light are contemplated
herein.
[0054] Optionally, the system 100 may include other sensors 140.
The other sensors 140 may include a LIDAR sensor, a radar sensor,
or other types of sensors. For instance, system 100 could include a
Global Positioning System (GPS), an Inertial Measurement Unit
(IMU), a temperature sensor, a speed sensor, a camera, or a
microphone. In such scenarios, any of the operational scenarios
and/or methods described herein could include receiving information
from the other sensors 140 and carrying out other operations or
method steps based, at least in part, on the information received
from the other sensors 140.
[0055] In an example embodiment, at least two of: the at least one
ToF sensor 110, the imaging sensor 120, and the at least one light
source 130 could be coupled to a common substrate. For example, the
at least one ToF sensor 110, the imaging sensor 120, and the at
least one light source 130 could be coupled to a vehicle. In some
embodiments, some or all elements of system 100 could provide at
least a portion of the object detection and/or navigation
capability of the vehicle. The vehicle could be a semi-autonomous
or fully-autonomous vehicle (e.g., a self-driving car). For
instance, system 100 could be incorporated into vehicle 300 as
illustrated and described in reference to FIGS. 3A, 4A, 4B, 6A, and
6B.
[0056] In some embodiments, system 100 could be part of a vehicle
control system utilized to detect and potentially identify nearby
vehicles, road boundaries, weather conditions, traffic signs and
signals, and pedestrians, among other features within the
environment surrounding the vehicle 300. For example, a vehicle
control system may use depth map information to help determine
control strategy for autonomous or semi-autonomous navigation. In
some embodiments, depth map information may assist the vehicle
control system to avoid obstacles while also assisting with
determining proper paths for navigation.
[0057] While some examples described herein include system 100 as
being incorporated into a vehicle, it will be understood that other
applications are possible. For example, system 100 could include,
or be incorporated into, a robotic system, an aerial vehicle, a
smart home device, a smart infrastructure system, etc.
[0058] System 100 includes a controller 150. In some embodiments,
the controller 150 could include an on-board vehicle computer, an
external computer, or a mobile computing platform, such as a
smartphone, tablet device, personal computer, wearable device, etc.
Additionally or alternatively, the controller 150 can include, or
could be connected to, a remotely-located computer system, such as
a cloud server network. In an example embodiment, the controller
150 may be configured to carry out some or all of the operations,
method blocks, or steps described herein. Without limitation, the
controller 150 could additionally or alternatively include at least
one deep neural network, another type of machine learning system,
and/or an artificial intelligence system.
[0059] The controller 150 may include one or more processors 152
and at least one memory 154. The processor 152 may include, for
instance, a microprocessor, an application-specific integrated
circuit (ASIC), or a field-programmable gate array (FPGA). Other
types of processors, circuits, computers, or electronic devices
configured to carry out software instructions are contemplated
herein.
[0060] The memory 154 may include a non-transitory
computer-readable medium, such as, but not limited to, read-only
memory (ROM), programmable read-only memory (PROM), erasable
programmable read-only memory (EPROM), electrically erasable
programmable read-only memory (EEPROM), non-volatile random-access
memory (e.g., flash memory), a solid state drive (SSD), a hard disk
drive (HDD), a Compact Disc (CD), a Digital Video Disk (DVD), a
digital tape, read/write (R/W) CDs, R/W DVDs, etc.
[0061] The one or more processors 152 of controller 150 may be
configured to execute instructions stored in the memory 154 so as
to carry out various operations and method steps/blocks described
herein. The instructions may be stored in a permanent or transitory
manner in the memory 154.
[0062] FIG. 2 illustrates an operating scenario 200 of the system
100, according to example embodiments. While the operating scenario
200 illustrates certain operations or blocks being in a certain
order and being carried out by certain elements of system 100, it
will be understood that other functions, orders of operations,
and/or timing arrangements are contemplated herein.
[0063] Block 210 may include the controller 150 causing the at
least one light source 130 to illuminate at least a portion of the
scene with illumination light according to a structured light
pattern. The structured light pattern could include, for example,
at least one of: a predetermined light pulse repetition rate, a
predetermined light pulse duration, a predetermined light pulse
intensity, or a predetermined light pulse duty cycle.
[0064] In some embodiments, the structured light pattern could
remain static over one or more scans within a given field of view.
Alternatively or additionally, the structured light pattern could
change dynamically. For example, the structured light pattern could
be adjusted based on objects within the environment, a region of
interest within the field of view; a time of day, presence of
retroreflectors, etc. In some embodiments, the structured light
pattern could include a checkerboard pattern, a speckle pattern, or
a striped pattern.
[0065] In some example embodiments, in response to determining a
retroreflector within a portion of a given field of view, the
intensity of the sector that had illuminated the retroreflector
could be "dialed down" (e.g., reducing a preamplifier gain or
otherwise changing how a photosignal from that sector is processed
in the analog and/or digital domain) and/or completely turned off
or ignored to avoid blooming effects. In such a manner, the sensor
may be better able to recover the remaining portions of the
scene.
[0066] Periodically (e.g., once every few of frames within a
maximum latency), the portion of field of view with the
retroreflector could be illuminated again to track the presence of
the retroreflector. If the sensor continues to indicate strongly
saturated pixels in response to illumination (e.g., indicating that
the retroreflective object is still present in that region of the
field of view), high energy illumination will not be provided to
the given region until such time that the system no longer observes
a retroreflector in that region. Such dynamic illumination could
reduce or eliminate stray light from retroreflectors and more
reliably recover the remainder of the scene which might otherwise
not produce reliable depth values. Without limitation, other types
of spatial, temporal, and/or spectral light patterns are
contemplated herein.
[0067] In an example embodiment, instruction 212 could include, for
example, a signal from the controller 150 to the light source 130
at time to. The instruction 212 could be indicative of the desired
structured light pattern and/or an illumination schedule, an
illumination level, or an illumination direction or sector, among
other examples.
[0068] In response to receiving the instruction 212, the light
source 130 could carry out block 214 to illuminate the scene
according to the structured light pattern. In some examples, the
light source 130 could illuminate one or more light-emitter
elements, which could be light-emitting diodes (LEDs), lasers,
strobe lights, or another type of light source. Such light-emitter
elements could be illuminated so as to provide the desired
structured light pattern (e.g., provide light along a desired set
of pointing/cone angles, illuminate light-emitter elements for a
desired time, illuminate light-emitter elements at a desired
frequency and duty cycle, etc.). In some embodiments, the light
source 130 could include an optical element, such as one or more
lenses, and/or a baffle so as to direct light toward a desired set
of pointing angles and/or cone angle.
[0069] Block 220 includes causing the at least one ToF sensor 110
to provide information (e.g., time of flight information)
indicative of a depth map of the scene based on the structured
light pattern provided by the light source 130. For example, at
time t.sub.1, block 220 could include providing an instruction 222
from the controller 150 to the ToF sensor 110. The instruction 222
could include a signal to trigger a depth mapping function of the
ToF sensor 110. Additionally or alternatively, the instruction 222
could include information indicative of a desired field of view for
scanning, a desired range for scanning, a desired resolution,
and/or other desired aspects of the depth map and/or ToF sensor
scan.
[0070] Block 224 could include the ToF sensor 110 obtaining a depth
map based, at least in part, on the structured light pattern
provided by the light source 130. That is, in response to receiving
the instruction 222, the ToF sensor 110 may carry out a
depth-mapping scan of a field of view of a scene. In an example
embodiment, the ToF sensor 110 could be operated between 10-100
MHz, however other operating frequencies are possible. In some
embodiments, the operating frequency of the ToF sensor 110 may be
adjusted based on a desired maximum depth sensing range. For
instance, the ToF sensor 110 could be operated at 20 MHz for a
desired depth sensing range of approximately 7.5 meters. In some
embodiments, the ToF sensor 110 could have a maximum desired depth
sensing range of 100 meters or more. In some embodiments that
involve multiple ToF sensors, the ToF sensors could be configured
to and/or instructed to carry out depth-mapping scans of different
fields of view of the scene and/or over different distance
ranges.
[0071] At time t.sub.2, upon obtaining the depth map according to
block 224, the ToF sensor 110 could provide information 226 to the
controller 150. The information 226 may be indicative of the depth
map of the scene. For example, the information 226 could include a
distance-based point map of the scene. Additionally or
alternatively, the information 226 could include a surface map of
objects determined within the scene. Other types of information 226
are possible and contemplated.
[0072] Block 230 includes causing the imaging sensor 120 to provide
information indicative of an image of the scene based on the
structured light pattern provided by the light source 130. As an
example, at time t.sub.3, the controller 150 could provide an
instruction 232 to the imaging sensor 120. The instruction 232
could include a signal for triggering an image capture function of
the imaging sensor 120. Furthermore, the instruction 232 could
include information regarding a desired exposure, ambient lighting
level, ambient lighting color temperature, time of day, etc. While
t.sub.1 and t.sub.3 are illustrated in FIG. 2 as being different,
in some embodiments, times t.sub.1 and t.sub.3 could be similar or
identical. That is, in some embodiments, at least some portions of
the depth mapping and image capture processes could be triggered
and conducted in parallel.
[0073] Block 234 includes, in response to receiving the instruction
232, the imaging sensor 120 obtaining an image of the scene
illuminated by the structured light pattern. In other words,
instruction 232 could trigger a physical shutter mechanism or a
digital shutter so as to initiate an image capture process.
[0074] Upon capturing the image, at time t.sub.4, the image sensor
120 could provide information 236 to the controller 150. The
information 236 could include, for example, the captured image as
well as other information, such as metadata regarding the captured
image (e.g., exposure time, aperture setting, imager sensitivity
(ISO), field of view extents, etc.). In some embodiments, the
information 236 could include RAW image data, however other
uncompressed and compressed image data formats (BMP, JPEG, GIF,
PNG, TIFF, etc.) are possible and contemplated.
[0075] Block 240 could include determining a high-resolution depth
map of the scene based on the depth map of the scene (e.g.,
information 226) and the image of the scene (e.g., information
236). In an example embodiment, the depth map information 226 and
the image information 236 could be compared and/or correlated using
various image processing algorithms. Such algorithms may include,
without limitation, texture synthesis, image resampling algorithms,
interpolation algorithms, image sharpening algorithms,
edge-detection algorithms, and image blurring algorithms, etc. As
such, the high-resolution depth map could include depth information
about the scene with a higher spatial resolution than that of the
depth map obtained by the ToF sensor 110. In some embodiments, the
spatial resolution could relate to a target resolution at a given
distance away from the system 100. Other spatial resolutions, both
along a two-dimensional surface and within three-dimensional space,
are possible and contemplated herein. As an example, the depth map
obtained by the ToF sensor 110 could provide a spatial resolution
between adjacent sampling points of 10 centimeters at a range of 20
meters. The high-resolution depth map could provide a spatial
resolution of less than 5 centimeters at a range of 20 meters. In
other embodiments, a high-resolution depth map could include other
spatial resolutions that may be sufficient to sense objects (e.g.,
other vehicles, pedestrians, obstacles, signs, signals, etc.)
within a field of view of the system 100.
[0076] Block 250 may include determining at least one inference
about the scene based on the depth map of the scene and,
optionally, the image of the scene. For example, the controller 150
could determine at least one inference about the scene based on the
high-resolution depth map determined in block 240. In such a
scenario, the at least one inference may include information about
one or more objects in an environment of a vehicle or an operating
context of the vehicle. In scenarios where the controller 150
includes a deep neural network, block 250 could be performed, at
least in part, by the deep neural network.
[0077] While the operating scenario 200 describes various
operations or blocks 210, 220, 230, 240, and 250 as being carried
out by the controller 150, it will be understood that at least some
of the operations of operating scenario 200 could be executed by
one or more other computing devices.
[0078] While operating scenario 200 describes various operations,
it will be understood that more or fewer operations are
contemplated. For example, the operations could further include
selecting an illumination schedule from among a plurality of
possible illumination schedules so as to provide a desired exposure
for the imaging sensor 120.
[0079] FIGS. 3A, 3B, and 3C illustrate various embodiments of the
system 100 and its elements. FIG. 3A illustrates a vehicle 300,
according to an example embodiment. The vehicle 300 may include one
or more sensor systems 302, 304, 306, 308, 310, 354a-d, and 356a-d.
In some examples, the one or more sensor systems 302, 304, 306,
308, and 310 could include LIDAR and/or radar sensor units. One or
more of the sensor systems 302, 304, 306, 308, and 310 may be
configured to rotate about an axis (e.g., the z-axis) perpendicular
to the given plane so as to illuminate an environment around the
vehicle 300 with light pulses and/or radar energy. Additionally or
alternatively, one or more of the sensor systems 302, 304, 306,
308, and 310 could include a movable mirror so as to direct emitted
light pulses and/or radar energy in the environment of the vehicle
300. For LIDAR-based sensors, determining various aspects of
reflected light pulses (e.g., the elapsed time of flight,
polarization, etc.,) may provide information about the environment
as described herein. Similarly, radar-based sensors may determine
information about a given scene based on how radar energy interacts
with the environment.
[0080] In an example embodiment, sensor systems 302, 304, 306, 308,
and 310 may be configured to provide respective point cloud
information or other types of information (e.g., maps, object
databases, etc.) that may relate to physical objects within the
environment of the vehicle 300. While vehicle 300 and sensor
systems 302 and 304 are illustrated as including certain features,
it will be understood that other types of sensors are contemplated
within the scope of the present disclosure.
[0081] FIG. 3B illustrates a front view of sensor unit 350,
according to an example embodiment. Sensor unit 350 could include a
housing 352. In some embodiments, the housing 352 could be coupled
to, or integrated into, the vehicle 300. In an example embodiment,
the sensor unit 350 may optionally include an imaging sensor 354,
which could be similar or identical to imaging sensor 120, as
illustrated and described in reference to FIG. 1. Additionally, the
sensor unit 350 could include a ToF sensor 356, which could be
similar or identical to ToF sensor 110, as illustrated and
described in reference to FIG. 1. While FIG. 3B illustrates imaging
sensor 354 and ToF sensor 356 as being disposed within a common
housing 352, the imaging sensor 354 and ToF sensor 356 could be
disposed in different locations. It will be understood that other
arrangements of such elements are possible and contemplated
herein.
[0082] FIG. 3C illustrates a light source 370, according to an
example embodiment. Light source 370 could include a housing 372.
In some embodiments, the housing 372 could be coupled to, or
integrated into, the vehicle 300. In an example embodiment, the
light source 370 may include a plurality of light-emitting elements
374a-h, which could be similar or identical to light source 130, as
illustrated and described in reference to FIG. 1. Light-emitting
elements 374a-h could be disposed in an array or in another spatial
arrangement. In an example embodiment, the light-emitting elements
374a-h could be light-emitting diodes (LEDs) or laser diodes. Other
types of light sources are possible and contemplated.
[0083] The light-emitting elements 374a-h could be configured to
emit light in the infrared (e.g., near infrared 700-1050 nm)
wavelength range. However, in some embodiments, other wavelengths
of light are contemplated (e.g., 1550 nm). In some embodiments, the
light-emitting elements 374a-h could be configured to emit light at
different wavelengths from each other. That is, the light-emitting
elements 374a-h could be configured to emit light at eight
different wavelengths. In such scenarios, system 100 and/or vehicle
300 could be configured to disambiguate light signals emitted by
discrete light-emitting elements (or between different light
sources 370) based on its wavelength. In some embodiments, the
multi-color light could be received by multi-color imaging sensors
and/or multi-color ToF sensors.
[0084] In some embodiments, light-emitting elements 374a-h could
include one or more optical elements configured to interact with
the light emitted from the light-emitting elements 374a-h. Without
limitation, the one or more optical elements could be configured to
redirect, shape, attenuate, amplify, or otherwise adjust the
emitted light. For example, the one or more optical elements could
include a mirror, an optical fiber, a diffractive optic element, an
aspherical lens, a cylindrical lens, or a spherical lens. Other
types of optical elements are possible and contemplated.
[0085] In some example embodiments, the light-emitting elements
374a-h could be operable so as to emit light toward different
spatial sectors (e.g., including different azimuthal angle ranges
and/or elevation angle ranges) of the environment around vehicle
300. Furthermore, in some embodiments, the light-emitting elements
374a-h could be operable to emit light at different times during a
given period of time. That is, each of the light-emitting elements
374a-h could be controlled to emit light during respective time
periods over a given time span. For example, the light-emitting
elements 374a-h could emit light in a serial pattern (e.g., one
light-emitting element lit after another in a "chase" pattern).
Additionally or alternatively, one or more of the light-emitting
elements 374a-h could emit light in a parallel fashion (e.g.,
several light-emitting element emitting light simultaneously).
[0086] Returning to FIG. 3A, vehicle 300 could include a plurality
of sensor units, which could be similar or identical to sensor unit
350, as illustrated and described in reference to FIG. 3B.
Furthermore, the respective sensor units could each include imaging
sensors 354a-d and ToF sensors 356a-d. As illustrated, the
respective pairs of imaging sensors 354a-d and ToF sensors 356a-d
could be coupled to, or integrated into, a front, right side, left
side, and rear portion of the vehicle 300. Other mounting types and
mounting locations are contemplated for the imaging sensors 354a-d
and ToF sensors 356a-d. For example, in some embodiments, the
imaging sensors 354a-d and ToF sensors 356a-d could be disposed in
a rotatable mount configured to rotate about the z-axis so as to
obtain imaging information and ToF information from an environment
around the vehicle 300.
[0087] While sensor systems 354a/356a, 354b/356b, 354c/356c, and
354d/356d are illustrated as being collocated, it will be
understood that other sensor arrangements are possible and
contemplated. Furthermore, while certain locations and numbers of
sensor systems are illustrated in FIGS. 3A-3C, it will be
understood that different mounting locations and/or different
numbers of the various sensor systems are contemplated.
[0088] Vehicle 300 could include a plurality of light sources
370a-d, which could be similar or identical to light source 130, as
illustrated and described in reference to FIG. 1. As illustrated,
light source 370a-d could be coupled to, or integrated into, a
front, right side, left side, and rear portion of the vehicle 300.
Other mounting types and mounting locations are contemplated for
the plurality of light sources 370a-d. For example, in some
embodiments, the light source 370 could be disposed in a rotatable
mount configured to rotate about the z-axis so as to emit light
toward a controllable azimuthal angle range.
[0089] FIG. 4A-4B illustrate various sensing scenarios 400 and 420.
In each case, for purposes of clarity, the sensing scenarios 400
and 420 may illustrate a subset of possible spatial sectors and
sensor profiles/ranges. It will be understood that other spatial
sectors are possible and contemplated within the scope of the
present disclosure. Furthermore, it will be understood that the
sensing scenarios 400 and 420 may illustrate only single
"snapshots" in time and that spatial sectors and sensor
profiles/ranges could be dynamically adjusted so as to periodically
or continuously change based on, among other factors, a
dynamically-changing operating context of the vehicle 300.
[0090] FIG. 4A illustrates an overhead/top view of vehicle 300 in a
sensing scenario 400, according to an example embodiment. Sensing
scenario 400 includes illuminating a front-facing sector of an
environment of the vehicle 300 with structured light pattern 402.
For example, light source 370a could emit light from one or more
light-emitting elements so as to illuminate the front-facing sector
of the vehicle 300 with the structured light pattern 402.
[0091] The structured light pattern 402 could be provided according
to a pulsed illumination schedule or a continuous-wave illumination
schedule. Other types of illumination schedules are contemplated.
For example, the structured light pattern 402 could be provided
"on-demand" from controller 150 or based on the operating context
of the vehicle 300. As an example, the structured light pattern 402
could be provided in low-light conditions (e.g., at night) or in
response to determining an object in the environment of the vehicle
300. As a non-limiting example, another sensor system of the
vehicle 300 could identify an ambiguous or unknown object (not
illustrated) ahead of the vehicle 300. The ambiguous or unknown
object could be identified for further analysis. In such a
scenario, the controller 150 could cause the light source 370a to
provide the structured light pattern 402 to the front-facing
sector.
[0092] While FIG. 4A illustrates a front-facing sector as being
illuminated, in some embodiments, the light source 370a may be
configured to adjust a pointing direction of the structured light
pattern 402. It will also be understood that the other light
sources 370b-d could provide similar structured light patterns into
various spatial sectors corresponding with their respective
positions. For example, light source 370d could emit light
according to the structured light pattern into a rear-facing
spatial sector.
[0093] It will be understood that while the structured light
pattern 402 and spatial sectors appear as being two-dimensional in
FIG. 4A-4B, three-dimensional spatial volumes are contemplated. For
example, the structured light pattern 402 and/or spatial sectors
could be defined as between an azimuthal angle range and also
between a maximum elevation angle and a minimum elevation
angle.
[0094] FIG. 4B illustrates an overhead/top view of the vehicle 300
in a sensing scenario 420, according to an example embodiment.
Sensing scenario 420 could include imaging sensor 354a obtaining
light from a field of view 404. At least a portion of the light
obtained by the imaging sensor 354a could include reflected or
refracted light after the structured light pattern 402 interacts
with the environment of the vehicle 300. The field of view 404
could include a front-facing spatial sector of the vehicle 300. In
some embodiments, the field of view 404 of the imaging sensor 354a
could partially or fully overlap with the volume illuminated by the
structured light pattern 402. Based on the light obtained from
field of view 404, the imaging sensor 354a may provide an image of
the scene based, at least in part, on the structured light pattern
402.
[0095] Sensing scenario 420 also illustrates ToF sensor 356a
obtaining light from a field of view 406. At least a portion of the
light obtained by the ToF sensor 356a could be from structured
light pattern 402 that has interacted with the environment of the
vehicle 300. The field of view 406 could include a front-facing
spatial sector of the vehicle 300. In some embodiments, the field
of view 406 of the ToF sensor 356a could partially or fully overlap
with the volume illuminated by structured light pattern 402. Based
on the light obtained from field of view 406, the ToF sensor 356a
may provide a depth map of the scene based, at least in part, on
the structured light pattern 402.
[0096] FIG. 4C illustrates various structured light patterns 430,
according to example embodiments. The various structured light
patterns 430 could include, for example, a vertical striped
structured light pattern 432, a dot array structured light pattern
434, a checkerboard structured light pattern 436, a diagonal
striped structured light pattern 438, a "dropout" structured light
pattern 440, and/or a speckle structured light pattern 442.
[0097] FIG. 4D illustrates a structured light pattern 444,
according to an example embodiment. As an example, structured light
pattern 444 could include a horizontal striped structured light
pattern 446. It will be understood that other structured light
patterns are possible and each is contemplated without
limitation.
[0098] In some embodiments, an illumination level (e.g.,
brightness) of some or all portions of the structure light patterns
430 could be dynamically adjusted based on objects within the scene
and/or prior information about the scene. As an example, the amount
of illumination provided to various portions of the scene could be
based on the presence of predicted or known highly-retroreflective
objects. In a scenario, the ToF sensor could capture an initial
scan of the scene while illuminating the scene at a relatively low
illumination level. As an example, the initial scan could include a
brief (e.g., 10 microsecond) illumination period. Such an initial
scan could provide information about retroreflectors present within
the scene. A subsequent scan of the scene could be performed at a
relatively high illumination level (e.g., 100 microsecond
illumination period, or longer) for portions of the scene where the
retroreflectors are not present. The subsequent scan could include
illuminating the portions of the scene having the retroreflectors
at a relatively low illumination level to confirm the presence of a
highly reflective object.
[0099] For example, in reference to FIG. 4C, if a retroreflective
region 435a is identified within a given scene during an initial
scan, then illumination of that retroreflective region 435a could
be reduced with respect to other regions 435b of the scene during a
subsequent scan. By dynamically adjusting the illumination level
within the scene, potential blooming issues and/or other problems
relating to retroreflectors could be avoided or reduced on a
near-real-time basis. Other ways to differentially illuminate
certain portions of the scene with respect to other portions of the
scene are contemplated and possible.
III. Example Methods
[0100] FIG. 5 illustrates a method 500, according to an example
embodiment. It will be understood that the method 500 may include
fewer or more steps or blocks than those expressly illustrated or
otherwise disclosed herein. Furthermore, respective steps or blocks
of method 500 may be performed in any order and each step or block
may be performed one or more times. In some embodiments, some or
all of the blocks or steps of method 500 may be carried out by
elements of system 100. For example, some or all of method 500
could be carried out by controller 150, ToF sensor(s) 110, and/or
imaging sensor(s) 120 as illustrated and described in relation to
FIG. 1. Furthermore, method 500 may be described, at least in part,
by the operating scenario 200, as illustrated in relation to FIG.
2. Yet further, method 500 may be carried out, at least in part, by
vehicles 300 or 400 as illustrated and described in relation to
FIG. 3A, 4A, 4B, 6A, or 6B. Method 500 may be carried out in
scenarios similar or identical to scenario 400 as illustrated and
described in relation to FIGS. 4A, 4B, and 4C. It will be
understood that other scenarios are possible and contemplated
within the context of the present disclosure.
[0101] Block 502 includes causing at least one light source to
illuminate a scene with a structured light pattern. The structured
light pattern could be similar or identical to structured light
pattern 402, 432, 434, 436, 438, 440, and 442, as illustrated and
described in FIGS. 4A, 4B, and 4C. In example embodiments, the
structured light pattern could include at least one of: a temporal
light pattern, a spatial light pattern, a predetermined light pulse
repetition rate, a predetermined light pulse duration, a
predetermined light pulse intensity, or a predetermined light pulse
duty cycle.
[0102] Block 504 includes receiving, from a time-of-flight (ToF)
sensor, information (e.g., time of flight information) about the
scene based on the structured light pattern. In an example
embodiment, the controller 150 could cause the ToF sensor to
initiate a depth scan based on the structured light pattern. In
some embodiments, a clock signal or trigger signal could be
provided to the ToF sensor to synchronize it with the one or more
light pulses emitted into the environment. Upon obtaining depth map
information, the ToF sensor could provide to the controller 150
information indicative of the depth map to the controller 150 or
another element of the system 100.
[0103] Block 506 includes determining a depth map of the scene
based on the received information. For example, determining the
depth map of the scene could include calculating distances to
objects in the environment based on the time of flight of light
pulses emitted into the environment. Other ways to determine the
depth map of the scene based on the received information are
contemplated.
[0104] Optionally, method 500 could include causing an imaging
sensor to provide information indicative of an image of the scene
based on the structured light pattern. In some embodiments, the
controller 150 could trigger a mechanical or electronic shutter of
the imaging sensor to open and obtain an image of the scene.
Additionally or alternatively, the controller 150 could provide
information about the scene (e.g., ambient light level, specific
sectors of concern, desired resolution, time of day, etc.).
Furthermore, the controller 150 or the light source 130 could
provide a clock signal or trigger signal so as to synchronize the
imaging sensor and light source. Upon obtaining the image of the
scene, the imaging sensor could provide information indicative of
the image to the controller 150 or another element of system
100.
[0105] Additionally or alternatively, method 500 could include
selecting a desired structured light pattern from among a plurality
of possible structured light patterns. In some embodiments, the
desired structured light pattern could be selected so as to provide
a desired exposure for the imaging sensor. Additionally or
alternatively, selecting the desired structured light pattern could
be based on a number of variables, including external light level,
other light sources, angle of sun, etc. As such, method 500 could
include selecting and/or adjusting the structured light pattern
based on an amount of ambient light (e.g., as measured from an
ambient light sensor), a time of day, and/or weather condition.
[0106] Optionally, method 500 could include determining a
high-resolution depth map (e.g., a depth map with higher resolution
than that provided by the ToF sensor individually) of the scene
based on the depth map of the scene and the image of the scene.
[0107] Block 508 includes determining at least one inference about
the scene based on the depth map of the scene and, optionally, the
image of the scene. In some embodiments, the at least one inference
could include information about one or more objects in an
environment of a vehicle or an operating context of the
vehicle.
[0108] In example embodiments, determining the at least one
inference could be performed by at least one deep neural network.
Additionally or alternatively, some or all blocks of method 500
could be carried out by computing systems implementing other types
of artificial intelligence-based algorithms.
[0109] FIGS. 6A and 6B illustrate sensing scenarios in the context
of the present disclosure. The sensing scenarios could relate to
system 100 (e.g., as illustrated and described in reference to FIG.
1), vehicle 300 (e.g., as illustrated and described in reference to
FIGS. 3A, 4A, and 4B), and method 500 (e.g., as illustrated and
described in reference to FIG. 5).
[0110] FIG. 6A illustrates a sensing scenario 600, according to an
example embodiment. As illustrated in FIG. 6A, a vehicle 300 could
be operating in an environment that includes one or more objects.
As shown, the vehicle 300 includes sensor units 302, 306, 308, and
310. For instance, the sensor unit 302 may include a first LIDAR
(not shown) and a second LIDAR (not shown). Further, for instance,
each of the sensor units 306, 308, and 310 may also include a
LIDAR. As shown, the vehicle 300 may additionally include imaging
sensors 354a-d, ToF sensors 356a-d and light sources 370a-d. It
will be understood that the vehicle 300 could include different
numbers and/or arrangements of imaging sensors 354a-d, ToF sensors
356a-d, and/or light sources 370a-d.
[0111] As shown, the environment of the vehicle 300 includes
various objects such as cars 614 and 616, road sign 618, tree 620,
building 622, street sign 624, pedestrian 626, dog 628, car 630,
driveway 632, and lane lines including lane line 634. In some
embodiments, these objects have different reflectivities, which can
make it more difficult to obtain accurate depth map information. In
accordance with the present disclosure, the vehicle 300 may perform
the methods and processes herein, such as method 500, to facilitate
autonomous operation of the vehicle 300 and/or accident avoidance
by the vehicle 300.
[0112] FIG. 6B illustrates a sensing scenario 650, according to an
example embodiment. In some embodiments, the vehicle 300 and its
associated light sources could emit light into its environment
according to one or more structured light patterns 652 and 654. For
example, as illustrated, a right-facing light source could
illuminate the environment with structured light pattern 654, which
could include a checkerboard pattern. Furthermore, a front-facing
light source could illuminate the environment with structured light
pattern 652.
[0113] Other scenarios are possible as well. Thus, the present
methods and systems may facilitate autonomous operation and/or
accidence avoidance for a vehicle such as the vehicle 300 by
utilizing one or more ToF sensors in combination with light sources
that are configured to illuminate the environment with structured
light patterns.
[0114] Systems and methods described herein may involve prior
information about the environment. Such prior information could
include a high-fidelity three-dimensional model of the local
environment of a vehicle and/or within a scene of the ToF sensor.
In such scenarios, the prior information could reside, at least in
part, at the vehicle and/or at a central or regional server.
[0115] In some embodiments, the prior information may be utilized
in combination with the ToF information/depth map to better
calibrate the sensors and/or to better localize the vehicle. That
is, a comparison between the prior information and at least one
depth map could help determine intrinsic and extrinsic
characteristics of the ToF sensor. In such scenarios, the
determined intrinsic and/or extrinsic characteristics could be used
to calibrate the ToF sensor. Additionally or alternatively, a
comparison between the prior information and the at least one depth
map could include aligning or registering the prior information
with the at least one depth map. In so doing, the
alignment/registration process could help determine a more-accurate
absolute position, heading, speed, or other characteristics of the
vehicle and/or other aspects of its environment. In other words,
the prior information could be utilized in conjunction with the at
least depth map to provide more accurate information about the
vehicle than the sensor information taken alone. In such scenarios,
the prior information could represent a reference frame within
which the vehicle could be localized.
[0116] FIG. 7 illustrates a method 700, according to an example
embodiment. Blocks and/or elements of method 700 could be similar
or identical to corresponding elements of methods 500 or 600, as
illustrated and described in reference to FIGS. 5 and 6
[0117] Block 702 includes providing prior information, which
includes three-dimensional information of a scene. The prior
information could include, for example, image, ToF, and/or LIDAR
data obtained previously. Prior information could additionally or
alternatively include a map, a point cloud, or depth map, or other
types of information.
[0118] Block 704 includes causing at least one light source to
illuminate the scene with a structured light pattern. The
structured light pattern could be similar or identical to other
structured light patterns described herein.
[0119] Block 706 includes causing the at least one ToF sensor to
provide time of flight information indicative of a depth map of the
scene based on the structured light pattern. As described herein,
the ToF sensor could be operated while illuminating the scene with
the structured light pattern. Doing so may provide more detailed
information about the depth of objects in the scene.
[0120] Additionally or alternatively, the prior information could
be utilized to improve depth estimation. In such a scenario, the
prior information could be projected into the depth map(s). Various
methods (e.g., ray tracing, Principle Components Ordination (PCoA),
Non-metric Multidimensional Scaling (NMDS), or other methods) could
be used to perform the projection of three-dimensional prior
information onto the depth map, each of which are contemplated
herein. By projecting the prior information into the depth map,
depth information could double-checked, calibrated, verified,
and/or estimated more accurately.
[0121] Yet further, the prior information could be utilized to
perform background subtraction. In such a scenario, the prior
information could include information about objects that are
outside a relevant sensor depth (e.g., far away from the vehicle).
In such situations, depth map information corresponding to objects
that are outside the relevant sensor depth could be ignored,
discounted, deleted, and/or processed at a lower resolution than
other, more relevant, regions of the environment.
[0122] Additionally, the prior information could be used, at least
in part, to determine where retroreflective objects may be within a
given environment. When a vehicle (and its ToF imaging system(s))
enter such an environment, it can adjust operation of the system so
as to mitigate the effects of the retroreflective objects. For
instance, the system could illuminate the environment corresponding
to a known retroreflective object at a lower intensity level as
compared to other regions of the environment. In such a scenario,
the hybrid imaging system can avoid "blooming" or "blinding"
effects that can occur due to retroreflective objects. Additionally
or alternatively, the hybrid imaging system may operate at a
different modulation frequency and/or illuminate the illumination
source at a different rate. Other ways to mitigate the effects of
retroreflectors are possible and contemplated herein.
[0123] In some embodiments, a plurality of frames/scans from the
ToF sensor could be utilized to obtain information about the scene,
which could be utilized together with other information described
in the present disclosure. For example, "optical flow" can be
obtained by a pattern of apparent motion of an object between two
consecutive ToF frames. The optical flow could include, for
example, a two-dimensional vector field that includes the
displacement of corresponding objects in the scene between a first
ToF frame and a second ToF frame. Based on the optical flow,
distances to the objects can be inferred and/or predicted. Such
distance information from the optical flow could be utilized to
constrain the range of depths estimated using ToF information. That
is, the optical flow could provide further information about ranges
of objects in a given scene. The rough depth information could be
used to determine operating parameters for the ToF sensor and/or
the illumination source. Additionally or alternatively, the rough
depth information could be used to bound or constrain a set of
operating parameters used by the system more generally.
[0124] The particular arrangements shown in the Figures should not
be viewed as limiting. It should be understood that other
embodiments may include more or less of each element shown in a
given Figure. Further, some of the illustrated elements may be
combined or omitted. Yet further, an illustrative embodiment may
include elements that are not illustrated in the Figures.
[0125] A step or block that represents a processing of information
can correspond to circuitry that can be configured to perform the
specific logical functions of a herein-described method or
technique. Alternatively or additionally, a step or block that
represents a processing of information can correspond to a module,
a segment, a physical computer (e.g., a field programmable gate
array (FPGA) or application-specific integrated circuit (ASIC)), or
a portion of program code (including related data). The program
code can include one or more instructions executable by a processor
for implementing specific logical functions or actions in the
method or technique. The program code and/or related data can be
stored on any type of computer readable medium such as a storage
device including a disk, hard drive, or other storage medium.
[0126] The computer readable medium can also include non-transitory
computer readable media such as computer-readable media that store
data for short periods of time like register memory, processor
cache, and random access memory (RAM). The computer readable media
can also include non-transitory computer readable media that store
program code and/or data for longer periods of time. Thus, the
computer readable media may include secondary or persistent long
term storage, like read only memory (ROM), optical or magnetic
disks, compact-disc read only memory (CD-ROM), for example. The
computer readable media can also be any other volatile or
non-volatile storage systems. A computer readable medium can be
considered a computer readable storage medium, for example, or a
tangible storage device.
[0127] While various examples and embodiments have been disclosed,
other examples and embodiments will be apparent to those skilled in
the art. The various disclosed examples and embodiments are for
purposes of illustration and are not intended to be limiting, with
the true scope being indicated by the following claims.
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