Method of and apparatus for obtaining object data by machine vision form polarization information

A method for obtaining data concerning the characteristics of an object surface comprising:

• directing light from a source toward an object surface to produce specular reflection from an object point on said surface;
• directing said specular reflection through a polarizer to an image plane:
• measuring the intensity of light received by a selected pixel on said image plane;
• incrementally rotating said polarizer through a series of angles with respect to a specular plane of incidence which includes said incident light, said reflected specular light, said object point and said selected pixel;
• measuring the intensity of the light received by said pixel for each incremental position of said polarizer;
• and
• determining therefrom the orientation of said specular plane of incidence.

Apparatus for obtaining data concerning the shape of the surface of an object, comprising:

• first and second spaced light sources;
• means directing light from said first and second sources onto the surface of an object, concerning which data is to be obtained, at angles of incidence that will produce specular reflection from a common region of incidence on said surface;
• a first sensor having an image plane including at least one pixel located for receiving reflected specular light from said first light source;
• a second sensor having an image plane including at least one pixel located for receiving reflected specular light from said second light source;
• first polarizing means located between said first light source and said first sensor for producing a first multiplicity of polarization components of reflected specular light from said first light source, the radiance of said components varying with the angle of polarization for each said first polarization component with respect to a first specular plane of incidence which includes said first light source, said first sensor, and said common region of incidence;
• second polarizing means located between said second light source and said second sensor for producing a second multiplicity of polarization components of reflected specular light from said second light source, the radiance of said second components varying with the angle of polarization for each said second polarization component with respect to a second specular plane of incidence which includes said second light source, said second sensor, and said common region of incidence, said first and second specular planes intersecting at said common region of incidence to define a common surface normal;
• and
• means responsive to the radiance of said first and second polarization components received at said first and second sensors, respectively, for locating the orientation of said first and second specular planes with respect to the surface of said object, to thereby locate the surface normal at said common region of incidence.

A method of obtaining data concerning an object surface, comprising:

• directing light toward an object surface to produce specular reflection from at least one region of light incidence on the surface;
• directing specular reflections from said surface through polarizing means to corresponding sensor means to obtain a multiplicity of polarization components of said specular reflections;
• measuring the intensity of the polarization components received by selected sensor means;
• determining the maximum polarization component intensity for light reflected from a selected point of incidence on said surface;
• determining the minimum polarization component intensity for light reflected from the selected point of incidence on said surface;
• and
• determining therefrom the orientation of the specular plane of incidence for the selected point of incidence.