Method of determining the 3d positions of points on the surface of an object

Abstract

A method of determining the 3D positions of points on the surface of an object, the method comprising obtaining an images of an object from a first view point and from a second view point, fixed relative to the viewpoint of the first view point wherein the images comprise a matrix of pixels, each of the pixels having an associated pixel value, processing the images by determining for pixels in a generated image weighted averages of the pixel values of a pixel and adjacent pixels, identifying corresponding portions of an object from a first view point and from a second view point on the basis of the weighted average values of pixels, and determining 3D positions of points corresponding to the corresponding portions of images.

1 . A method of determining the 3D positions of points on the surface of an object, the method comprising:
 obtaining an image of an object from a first view point and from a second view point, fixed relative to the viewpoint of the first view point wherein the images comprise a matrix of pixels, each of the pixels having an associated pixel value;   processing the images by determining for pixels in a generated image weighted averages of the pixel values of a pixel and adjacent pixels;   identifying corresponding portions of an object from a first view point and from a second view point on the basis of the weighted average values of pixels; and   determining 3D positions of points corresponding to the corresponding portions of images.   
     
     
         2 . The method of  claim 1 , wherein processing the images by determining for pixels in a generated image weighted averages of the pixel values of a pixel and adjacent pixels comprises processing image data by applying an approximation of a Gaussian blur to blocks of adjacent pixels. 
     
     
         3 . The method of  claim 2 , wherein the weighted average comprises scaling a pixel value by a quarter, pixel values for immediately adjacent pixels by and eight and pixel values for diagonally adjacent pixels by a sixteenth. 
     
     
         4 . The method of  claim 1 , further comprising scaling pixel values below a first threshold so as to increase the differences in pixel values corresponding to different light levels in darker areas of obtained images. 
     
     
         5 . The method of  claim 4 , further comprising scaling pixel values above a second threshold so as to reduce the differences in pixel values corresponding to different light levels in lighter areas of an obtained image. 
     
     
         6 . The method of  claim 5 , further comprising mapping pixel values between the first and second threshold by mapping the pixel values to values between the scaled values corresponding to the first and second thresholds. 
     
     
         7 . The method of  claim 1 , wherein the pixel values comprise n bit data and the pixel values are truncated by eliminating the least significant bits prior to being utilised to identify corresponding portions of an object from a first view point and from a second view point. 
     
     
         8 . The method of  claim 1 , wherein the pixel values comprise n bit data and the pixel values are reduced the bit length prior to being utilised to identify corresponding portions of an object from a first view point and from a second view point on the basis of a rounding of the more significant bits of the pixel values. 
     
     
         9 . The method of  claim 1 , wherein identifying corresponding portions of an object from a first view point and from a second view point on the basis of the weighted average values of pixels comprises identifying matching portions of images the size of said portions being greater than the areas of image utilised to determine weighted averages of averages of the pixel values of a pixel and adjacent pixels. 
     
     
         10 . A computer readable medium storing computer interpretable instructions which when interpreted by a programmable computer cause the computer to perform a method in accordance with  claim 1 .