Patent ID: 6836562
Filing Date: 2004-12-28
Classification: G06T,H04N

Abstract:
A method for determining a gradient magnitude image from a range image, the range image including a plurality of intensity values at pixel locations, comprising:determining, for each pixel (i,j), a horizontal central difference dx, and a vertical central difference dy; setting a 2D gradient magnitude at each pixel (i,j) in a gradient magnitude image IGM to 0.5*sqrt(dx2+dy2+4); scaling the range image to produce a scaled range image where a unit intensity value at each pixel corresponds to a unit distance value; selecting a 3D point p; and further comprising: determining a magnitude of a gradient at point p from the scaled range image and the gradient magnitude image IGM comprising: perpendicularly projecting point p onto the scaled range image to determine a location (x,y); interpolating a gradient magnitude at the location (x,y) from the corresponding 2D gradient magnitude image values near the location (x,y); and setting the magnitude of the gradient at point p to the interpolated gradient magnitude at location (x,y).