Acquisition of surface normal maps from spherical gradient illumination

A method of generating a surface normal map of an object, comprising:

• illuminating a surface of the object with one or more gradient illumination patterns using a plurality of light sources;
• generating data representative of the light reflected from the illuminated surface of the object using an optical imaging system;
• and
• processing the data so as to estimate the surface normal map of the object using a processing system.

An apparatus for separately generating a specular normal map and a diffuse normal map of a surface of an object, comprising:

• a plurality of light sources having intensities that are controllable so as to generate one or more gradient illumination patterns;
• a set of polarizers adapted to be positioned relative to the light sources so as to polarize light from the light sources;
• wherein the light sources and the set of polarizers are arranged to illuminate the surface of the object with one or more polarized gradient illumination patterns;
• a camera configured to receive light that is reflected from the illuminated surface of the object, and to generate from the reflected light photographic data of the surface of the object;
• a camera polarizer configured to polarize the reflected light in a way that specularly reflected light is separated from diffusely reflected light, before the reflected light is received by camera;
• and
• a processing system configured to generate, from the photographic data, specular reflectance data representative of the specularly reflected light and diffuse reflectance data representative of the diffusely reflected light, the processing system further configured to estimate a specular normal map from the specular reflectance data and a diffuse normal map from the diffuse reflectance data.

A method of separately generating a specular normal map and a diffuse normal map of a surface of an object, comprising:

• illuminating the surface of the object with one or more polarized spherical gradient illumination patterns using a plurality of light sources;
• polarizing light reflected from the illuminated surface of the object in a way that separates specularly reflected light from diffusely reflected light using a set of polarizers;
• generating specular reflectance data representative of the specularly reflected light and diffuse reflectance data representative of the diffusely reflected light using an optical imaging system;
• estimating a specular normal map from the specular reflectance data using a processing system;
• and
• estimating a diffuse normal map from the diffuse reflectance data using the processing system.

An image rendering system for rendering an image of an object, the image comprising a plurality of pixels, the image rendering system comprising:

• a plurality of light sources having intensities that are controllable so as to generate one or more spherical gradient illumination patterns;
• a set of polarizers adapted to be positioned relative to the light sources so as to polarize light from the light sources;
• wherein the light sources and the set of polarizers are arranged to illuminate the surface of the object with one or more polarized spherical gradient illumination patterns;
• a camera configured to receive light that is reflected from the illuminated surface of the object, and to generate from the reflected light photographic data of the surface of the object;
• a camera polarizer configured to polarize the reflected light, the camera polarizer having an orientation relative to the set of polarizers that is adjustable so as to separate specularly reflected light from diffusely reflected light, before the reflected light is received by the camera;
• and
• a processing system configured to generate specular reflectance data for the specularly reflected light and diffuse reflectance data for the diffusely reflected light, and to estimate a specular normal map from the specular reflectance data and a diffuse normal map from the diffuse reflectance data;
• the processing system further configured to render a specular reflectance component of each of the pixels in the image using the specular normal map estimated from the specular reflectance data, and to render a diffuse reflectance component of each of the pixels in the image using the diffuse normal map estimated from the diffuse reflectance data.

A method of rendering an image of an object, the image comprising a plurality of pixels, the method comprising:

• illuminating the surface of the object with one or more polarized spherical gradient illumination patterns;
• polarizing light reflected from the illuminated surface of the object in a way that separates specularly reflected light from diffusely reflected light;
• generating specular reflectance data representative of the specularly reflected light and diffuse reflectance data representative of the diffusely reflected light;
• estimating a specular normal map from the specular reflectance data, and separately estimating a diffuse normal map from the diffuse reflectance data;
• rendering a specular reflectance component of each of the pixels in the image using the specular normal map estimated from the specular reflectance data;
• and
• rendering a diffuse reflectance component of each of the pixels in the image using the diffuse normal map estimated from the diffuse reflectance data.

A high resolution scanning system, comprising:

• a plurality of light sources having intensities that are controllable so as to generate one or more spherical gradient illumination patterns;
• a set of polarizers adapted to be positioned relative to the light sources so as to polarize light from the light sources;
• wherein the light sources and the set of polarizers are arranged to illuminate the surface of the object with one or more polarized spherical gradient illumination patterns;
• a three-dimensional scanning system configured to obtain a three-dimensional scan of the illuminated object's geometry, the three dimensional scan having a substantially medium resolution;
• another polarizer configured and arranged to polarize the reflected light so that specularly reflected light is separated from diffusely reflected light, before the reflected light is received by the scanning system;
• a processing system configured to generate specular reflectance data representative of the specularly reflected light and to estimate a specular normal map from the specular reflectance data, the processing system further configured to increase resolution of the geometry obtained from the three-dimensional scanning system, using the specular normal map.

A high resolution scanning system, comprising:

• a plurality of light sources having intensities that are controllable so as to generate one or more spherical gradient illumination patterns;
• a set of polarizers adapted to be positioned relative to the light sources so as to polarize light from the light sources;
• wherein the light sources and the set of polarizers are arranged to illuminate the surface of the object with one or more polarized spherical gradient illumination patterns;
• a video projector configured to project one or more structured light patterns onto the illuminated surface of the object;
• one or more cameras configured to receive light that is reflected from the illuminated surface of the object on which the structured light patterns have been projected, and to generate photographic data from the received light;
• a camera polarizer configured and arranged to polarize the reflected light so that specularly reflected light is separated from diffusely reflected light, before the reflected light is received by camera;
• a processing system configured to generate specular reflectance data representative of the specularly reflected light and to estimate a specular normal map from the specular reflectance data, the processing system further configured to increase the resolution of the photographic data using the specular normal map.