Simulating an Infrared Emitter Array in a Video Monitoring Camera to Construct a Lookup Table for Depth Determination

Abstract

A process generates lookup tables for estimating spatial depth in a scene. The process identifies subsets of illuminators of a camera system that has a 2-dimensional array of image sensors and illuminators in fixed locations relative to the array, and partitions the image sensors into a plurality of pixels. For each pixel, and for each of m distinct depths from the respective pixel, the process simulates a virtual surface at the respective depth. For each of the subsets of illuminators, the process determines an expected light intensity at the pixel based on the respective depth. The process forms an intensity vector using the expected light intensities for each of the distinct subsets and normalizes the intensity vector. For each pixel, the process constructs a lookup table comprising the normalized vectors corresponding to the pixel. The lookup table associates each normalized vector with the depth of the corresponding simulated surface.

What is claimed is: 
     
         1 . A method of generating a lookup table for use in estimating spatial depth in a visual scene, comprising:
 at a server having one or more processors, and memory storing one or more programs configured for execution by the one or more processors:   identifying a plurality of distinct subsets of IR illuminators of a camera system that has a 2-dimensional array of image sensors and a plurality of IR illuminators in fixed locations relative to the array of image sensors;   partitioning the image sensors into a plurality of pixels;   for each pixel, and for each of m distinct depths from the respective pixel:
 simulating a virtual surface at the respective depth; 
 for each of the plurality of distinct subsets of IR illuminators, determining an expected IR light intensity at the respective pixel based on the respective depth and based on only the respective subset of IR illuminators emitting IR light; 
 forming an intensity vector using the expected IR light intensities for each of the distinct subsets; and 
 normalizing the intensity vector; and 
   for each pixel, constructing a lookup table comprising the normalized vectors corresponding to the pixel, wherein the lookup table associates each respective normalized vector with the respective depth of the respective simulated surface.