Patent ID: 7447335

Claim:
A method for detecting an object disposed on the surface of the earth comprising: selecting a site on the surface of the earth; providing a surface finish representative of an object to be detected; obtaining a diffuse reflectance spectrum of said surface finish; identifying a first inflection point of the largest increase in slope of the diffuse reflectance spectrum of said surface finish; associating a first wavelength region with said first inflection point; identifying a second inflection point of the largest decrease in slope of the diffuse reflectance spectrum of said surface finish; associating a second wavelength region with said second inflection point; choosing a specific area of said selected site for imaging; passing light reflected from said specific area through a first bandpass filter that transmits light in said first wavelength region; forming a first image of said specific area, comprised of light transmitted through said first bandpass filter, upon an optical sensor comprised of pixels; passing light reflected from said specific area through a second bandpass filter that transmits light in said second wavelength region; forming a second image of said specific area, comprised of light transmitted through said second bandpass filter, upon an optical sensor comprised of pixels such that each pixel of said second image is correlated with a pixel of said first image of said specific area; calculating a ratio between each pair of correlated pixels of said first image and said second image; defining a threshold magnitude; calculating for each pair of said correlated pixels a value proportional to the difference between said threshold magnitude and the magnitude of said ratio; assigning each said value to a pixel corresponding to each pair of said correlated pixels to form a third image of said specific area in which pixels on which surface finish reflectance is imaged have greater value than pixels on which surface soil reflectance is imaged.