Camera calibration

Abstract

A depth map generating method includes obtaining one or more images from each of one or more imaging devices, and processing the one or more images from each of the one or more imaging devices based on calibration parameters for the one or more imaging devices to generate a three-dimensional depth map. The calibration parameters are determined using a plurality of calibration images of a calibration target from each of the one or more imaging devices. The calibration target includes a plurality of features arranged in a repeating pattern and one or more reference markers each uniquely identifiable within each calibration image of the plurality of calibration images. The plurality of calibration images include at least one calibration image capturing less than all of the plurality of features.

What is claimed is: 
     
         1 . A depth map generating method comprising:
 obtaining one or more images from each of one or more imaging devices; and   processing, with aid of one or more processors, the one or more images from each of the one or more imaging devices based on calibration parameters for the one or more imaging devices to generate a three-dimensional depth map;   wherein:
 the calibration parameters are determined using a plurality of calibration images of a calibration target from each of the one or more imaging devices, the calibration target including a plurality of features arranged in a repeating pattern and one or more reference markers each uniquely identifiable within each calibration image of the plurality of calibration images; and 
 the plurality of calibration images include at least one calibration image capturing less than all of the plurality of features. 
   
     
     
         2 . The method of  claim 1 , wherein the one or more reference markers include a plurality of reference markers, and each of the plurality of reference markers on the calibration target forms one of vertices of an irregular polygon on the calibration target with no more than two of the plurality of reference markers being on a same line. 
     
     
         3 . The method of  claim 2 , wherein each of the plurality of reference markers in the each calibration image forms one of vertices of an irregular polygon in the each calibration image. 
     
     
         4 . The method of  claim 1 , wherein:
 the one or more imaging devices are carried by an unmanned aerial vehicle; and   the depth map includes information indicating distances of one or more objects from the unmanned aerial vehicle.   
     
     
         5 . The method of  claim 1 , wherein the calibration parameters include at least one of a focal length, a position of a principal point, a pixel size, or an optical distortion for each of the one or more imaging devices. 
     
     
         6 . The method of  claim 1 , wherein the calibration parameters include a position and an orientation of each of the one or more imaging devices relative to the calibration target. 
     
     
         7 . The method of  claim 1 , wherein processing the one or more images includes reducing optical distortion in at least one of the one or more images. 
     
     
         8 . The method of  claim 1 , wherein the one or more imaging devices include a first camera and a second camera that capture images at substantially the same time. 
     
     
         9 . The method of  claim 8 , wherein processing the one or more images includes identifying one or more features present in both an image captured by the first camera and a corresponding image captured by the second camera. 
     
     
         10 . The method of  claim 8 , wherein processing the one or more images includes determining a disparity between an image captured by the first camera and a corresponding image captured by the second camera. 
     
     
         11 . A depth map generating system comprising:
 one or more imaging devices; and   one or more processors that are collectively or individually configured to:
 obtain one or more images from each of the one or more imaging devices; and 
 process the one or more images from each of the one or more imaging devices based on calibration parameters for the one or more imaging devices to generate a three-dimensional depth map; 
   wherein:
 the calibration parameters are determined using a plurality of calibration images of a calibration target from each of the one or more imaging devices, the calibration target including a plurality of features arranged in a repeating pattern and one or more reference markers each uniquely identifiable within each calibration image of the plurality of calibration images; and 
 the plurality of calibration images include at least one calibration image capturing less than all of the plurality of features. 
   
     
     
         12 . The system of  claim 11 , wherein the one or more reference markers include a plurality of reference markers, and each of the plurality of reference markers on the calibration target forms one of vertices of an irregular polygon on the calibration target with no more than two of the plurality of reference markers being on a same line. 
     
     
         13 . The system of  claim 12 , wherein each of the plurality of reference markers in the each calibration image forms one of vertices of an irregular polygon in the each calibration image. 
     
     
         14 . The system of  claim 11 , wherein:
 the one or more imaging devices are carried by an unmanned aerial vehicle; and   the depth map includes information indicating distances of one or more objects from the unmanned aerial vehicle.   
     
     
         15 . The system of  claim 11 , wherein the calibration parameters include at least one of a focal length, a position of a principal point, a pixel size, or an optical distortion for each of the one or more imaging devices. 
     
     
         16 . The system of  claim 11 , wherein the calibration parameters include a position and an orientation of each of the one or more imaging devices relative to the calibration target. 
     
     
         17 . The system of  claim 11 , wherein the one or more processors are further configured to reduce optical distortion in at least one of the one or more images. 
     
     
         18 . The system of  claim 11 , wherein the one or more imaging devices include a first camera and a second camera that capture images at substantially the same time. 
     
     
         19 . The system of  claim 18 , wherein the one or more processors are further configured to identify one or more features present in both an image captured by the first camera and a corresponding image captured by the second camera. 
     
     
         20 . The system of  claim 18 , wherein the one or more processors are further configured to determine a disparity between an image captured by the first camera and a corresponding image captured by the second camera.