Methods and apparatus for imaging volume data with shading

A method of generating a two dimensional rendering from three dimensional volume data comprising the steps of:

• providing a first image volume, said first image volume representing said three dimensional data set;
• storing said first image volume in a first image memory as a plurality of homogeneous storage arrays, each array comprising a plurality of planes having a plurality of volume elements (voxels);
• generating a second image volume from said first image volume by combining one of said planes of voxels with the next consecutive of said planes of voxels along a selected path;
• repeating the prior step for each consecutive of said planes of voxels with each generated combination image volume through the nth plane of voxels where n represents the total number of said planes of voxels;
• said combination image volume having voxels whose color and opacity values are based on the percentage composition of the color and opacity values of voxels contained in combined planes of voxels;
• defining a gradient vector G for each said voxel, said gradient vector representative of the change in opacity across each voxel relative to neighboring voxels disposed adjacent said voxel, said gradient vector being normal to an inferred surface at said voxel, and having a greater magnitude for a voxel identifying a surface than for a voxel identifying a solid;
• multiplying the color and opacity values of each voxel by the magnitude of said gradient of each voxel;
• providing said voxels of said combination image volume to a display means whereby a surface of an image volume is determined and is capable of display on said display means.