US 5,793,900 A · Generating categorical depth maps using passive defocus sensing

Abstract

A method is disclosed for generating a categorical depth map of a scene using passive defocus sensing. In a preferred embodiment three synchronized CCD cameras focused at different distances detect three images of the same scene. An image processor partitions the images into an array of regions and calculates a sharpness value for each region. The sharpness value for a region is calculated by summing over all pixels (x,y) in the region the absolute difference in the intensity value of a pixel (x,y)( with pixel (x-k,y-l), where k and l are constants. The image processor then constructs a depth map of the scene by determining for each region the image with the greatest sharpness in that region. An application of the invention to a mobile robot control system is described in detail. Among other applications, the method may be used for collision avoidance, object detection, and speed measurement.

Claims20

Dependent claims

A method for generating a categorical depth map of a scene, the depth map comprising m depth map regions, where m.gtoreq.1, the method comprising the steps of:

detecting n images of the scene using n cameras focused at different distances, where n>1;
dividing each of the n images into m predetermined two-dimensional image regions such that each depth map region corresponds to n similar image regions taken from the n images;
determining a sharpness value for each region of the m image regions in each image of the n images;
identifying, for each depth map region, an image number of a sharpest image selected from the n similar image regions taken from the n images, wherein the sharpest image has a maximal sharpness value;
and
assigning a categorical depth value to each depth map region of the m depth map regions, where the depth value for a depth map region is determined from an image number of the sharpest image identified for the depth map region.

3 more elements

Dependencies are inferred from the claim text.

Generating categorical depth maps using passive defocus sensing

Life of this patent

Generating categorical depth maps using passive defocus sensing

Life of this patent

Abstract

Claims20