Dynamic Range for Depth Sensing

Abstract

An example system includes a patterned light projector operable to direct first and second portions of patterned light toward first and second surfaces, respectively, in an environment. The first and second surfaces may be at first and second distances, respectively, from the structured light projector. A graduated optical filter may be situated along an optical path of the patterned light. The graduated optical filter includes first and second regions to attenuate an intensity of the first and second portions of the patterned light, respectively, by first and second amounts, respectively. The first amount is greater than the second amount. The system additionally includes an image sensor operable to generate image data based on at least the first and second portions of the patterned light and a processor configured to determine first and second values indicative of an estimate of the first and second distances, respectively, based on the image data.

What is claimed is: 
     
         1 . A method comprising:
 projecting, by a patterned light projector, a patterned light onto an environment;   generating, by an image sensor, first image data based on the environment illuminated by the patterned light;   determining (i), based on a first portion of the first image data, a first amount by which to attenuate an intensity of a first portion of the patterned light and (ii), based on a second portion of the first image data, a second amount by which to attenuate an intensity of a second portion of the patterned light;   attenuating (i) the intensity of the first portion of the patterned light by the first amount and (ii) the intensity of the second portion of the patterned light by the second amount; and   generating, by the image sensor, second image data based on the environment illuminated by the first portion of the patterned light attenuated by the first amount and the second portion of the patterned light attenuated by the second amount.   
     
     
         2 . The method of  claim 1 , wherein a first portion of the patterned light is directed toward a first surface in the environment and a second portion of the patterned light is directed toward a second surface in the environment, wherein the first portion of the first image data represents the first surface illuminated by the first portion of the patterned light, and wherein the second portion of the first image data represents the second surface illuminated by the second portion of the patterned light. 
     
     
         3 . The method of  claim 1 , wherein the first amount is greater than the second amount such that an attenuated intensity of the second portion of the patterned light is greater than an attenuated intensity of the first portion of the patterned light. 
     
     
         4 . The method of  claim 1 , wherein the first image data represents the environment illuminated by the patterned light that has been projected with a uniform intensity. 
     
     
         5 . The method of  claim 1 , wherein determining (i) the first amount by which to attenuate the intensity of the first portion of the patterned light and (ii) the second amount by which to attenuate the intensity of the second portion of the patterned light comprises:
 determining (i) a first extent of exposure of the first portion of the first image data and (ii) a second extent of exposure of the second portion of the first image data; and   determining (i) the first amount based on the first extent of exposure and (ii) the second amount based on the second extent of exposure.   
     
     
         6 . The method of  claim 1 , wherein determining (i) the first amount by which to attenuate the intensity of the first portion of the patterned light and (ii) the second amount by which to attenuate the intensity of the second portion of the patterned light comprises:
 determining (i), based on the first portion of the first image data, a first value indicative of a first distance to a first surface in the environment and (ii), based on the second portion of the first image data, a second value indicative of a second distance to a second surface in the environment; and   determining (i) the first amount based on the first value and (ii) the second amount based on the second value.   
     
     
         7 . The method of  claim 1 , wherein attenuating (i) the intensity of the first portion of the patterned light by the first amount and (ii) the intensity of the second portion of the patterned light by the second amount comprises:
 controlling a spatial light modulator to cause (i) a first region of the spatial light modulator to attenuate by the first amount an intensity of a first portion of light emitted therefrom and (ii) a second region of the spatial light modulator to attenuate by the second amount an intensity of a second portion of light emitted therefrom.   
     
     
         8 . The method of  claim 7 , wherein controlling the spatial light modulator comprises:
 controlling respective sizes of respective apertures of the first portion of the spatial light modulator and the second portion of the spatial light modulator.   
     
     
         9 . The method of  claim 7 , wherein controlling the spatial light modulator comprises:
 controlling respective opacities of respective pixels of the first portion of the spatial light modulator and the second portion of the spatial light modulator.   
     
     
         10 . The method of  claim 1 , further comprising:
 determining, based on the second image data, (i) a first value indicative of a first distance to a first surface in the environment and (ii) a second value indicative of a second distance to a second surface in the environment, wherein the first surface is illuminated by the first portion of the patterned light attenuated by the first amount and the second surface is illuminated by the second portion of the patterned light attenuated by the second amount.   
     
     
         11 . The method of  claim 1 , wherein the image sensor forms part of a stereoscopic camera that comprises a second image sensor, and wherein the method further comprises:
 generating, by the second image sensor, third image data based on the environment illuminated by the first portion of the patterned light attenuated by the first amount and the second portion of the patterned light attenuated by the second amount; and   determining, based on the second image data and the third image data, a value indicative of a distance to a surface in the environment.   
     
     
         12 . The method of  claim 1 , further comprising:
 causing a robotic device to navigate through the environment based on the second image data.   
     
     
         13 . A system comprising:
 a patterned light projector configured to project a patterned light onto an environment;   an image sensor; and   a control system configured to perform operations comprising:
 causing the image sensor to generate first image data based on the environment illuminated by the patterned light; 
 determining (i), based on a first portion of the first image data, a first amount by which to attenuate an intensity of a first portion of the patterned light and (ii), based on a second portion of the first image data, a second amount by which to attenuate an intensity of a second portion of the patterned light; 
 causing the patterned light projector to attenuate (i) the intensity of the first portion of the patterned light by the first amount and (ii) the intensity of the second portion of the patterned light by the second amount; and 
 causing the image sensor to generate second image data based on the environment illuminated by the first portion of the patterned light attenuated by the first amount and the second portion of the patterned light attenuated by the second amount. 
   
     
     
         14 . The system of  claim 13 , wherein a first portion of the patterned light is directed toward a first surface in the environment and a second portion of the patterned light is directed toward a second surface in the environment, wherein the first portion of the first image data represents the first surface illuminated by the first portion of the patterned light, and wherein the second portion of the first image data represents the second surface illuminated by the second portion of the patterned light. 
     
     
         15 . The system of  claim 13 , wherein the first amount is greater than the second amount such that an attenuated intensity of the second portion of the patterned light is greater than an attenuated intensity of the first portion of the patterned light. 
     
     
         16 . The system of  claim 13 , wherein determining (i) the first amount by which to attenuate the intensity of the first portion of the patterned light and (ii) the second amount by which to attenuate the intensity of the second portion of the patterned light comprises:
 determining (i) a first extent of exposure of the first portion of the first image data and (ii) a second extent of exposure of the second portion of the first image data; and   determining (i) the first amount based on the first extent of exposure and (ii) the second amount based on the second extent of exposure.   
     
     
         17 . The system of  claim 13 , wherein determining (i) the first amount by which to attenuate the intensity of the first portion of the patterned light and (ii) the second amount by which to attenuate the intensity of the second portion of the patterned light comprises:
 determining (i), based on the first portion of the first image data, a first value indicative of a first distance to a first surface in the environment and (ii), based on the second portion of the first image data, a second value indicative of a second distance to a second surface in the environment; and   determining (i) the first amount based on the first value and (ii) the second amount based on the second value.   
     
     
         18 . The system of  claim 13 , wherein causing the patterned light projector to attenuate (i) the intensity of the first portion of the patterned light by the first amount and (ii) the intensity of the second portion of the patterned light by the second amount comprises:
 controlling a spatial light modulator to cause (i) a first region of the spatial light modulator to attenuate by the first amount an intensity of a first portion of light emitted therefrom and (ii) a second region of the spatial light modulator to attenuate by the second amount an intensity of a second portion of light emitted therefrom.   
     
     
         19 . The system of  claim 13 , wherein the operations further comprise:
 determining, based on the second image data, (i) a first value indicative of a first distance to a first surface in the environment and (ii) a second value indicative of a second distance to a second surface in the environment, wherein the first surface is illuminated by the first portion of the patterned light attenuated by the first amount and the second surface is illuminated by the second portion of the patterned light attenuated by the second amount.   
     
     
         20 . A non-transitory computer readable storage medium having stored thereon instructions that, when executed by a computing system, cause the computing system to perform operations comprising:
 causing a patterned light projector to project a patterned light onto an environment;   causing an image sensor to generate first image data based on the environment illuminated by the patterned light;   determining (i), based on a first portion of the first image data, a first amount by which to attenuate an intensity of a first portion of the patterned light and (ii), based on a second portion of the first image data, a second amount by which to attenuate an intensity of a second portion of the patterned light;   causing the patterned light projector to attenuate (i) the intensity of the first portion of the patterned light by the first amount and (ii) the intensity of the second portion of the patterned light by the second amount; and   causing the image sensor to generate second image data based on the environment illuminated by the first portion of the patterned light attenuated by the first amount and the second portion of the patterned light attenuated by the second amount.