Pixar

Robert A Drebin

Loren C Carpenter

An imaging system for providing apparatus and method for projecting a two dimensional (2D) representation of three dimensional (3D) volumes where surface boundaries and objects internal to the volumes are readily shown, and hidden surfaces and the surface boundaries themselves are accurately rendered. In the present invention, the two dimensional image produced is capable of having the same resolution as the sampling resolution of the input image image volume of interest. This is accomplished through the implementation of methods for determining 'partial volumes' of voxels. Partial voluming provides for the assignment of selected colors and opacities to different materials (or data components) represented in an image data volume based on the percentage composition of materials represented in each voxel of the image volume. Unlike prior art systems, such as those that use thresholding techniques, the imaging of the present invention has a high degree of precision and definition that is independent of image volume on a per voxel basis.

Method and apparatus for imaging volume data using voxel values

Method and apparatus for shading an image volume so that surfaces and boundaries may be rendered to subvoxel accuracy. A gradient vector is generated for each voxel of an image volume by calculating the change in opacity across that voxel in relation to its immediate neighbors. The gradient in the X, Y and Z direction of a three-dimensional voxel array is used to define a gradient length. By multiplying the RGBA values of individual voxels by their gradient length, a image volume may be shaded so that surfaces remain, but the interiors of solids are rendered more transparent revealing additional detail. Surfaces are shaded by multiplying the RGBA values of each voxel by a shading function. A reference point for a light source illuminating the displayed image volume is defined. A light vector is chosen for each voxel, a shading function is then generated based on the angle between the gradient vector and the light vector. The shading function allows for inputs for backlighting and side lighting.

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Corte Madera, CA, United States of America

Robert A Drebin