Patent ID: 6940507

Claim:
A method for rendering a volume of voxel data with shading and opacity, wherein each voxel comprises a value representative of a parameter at a location within the volume and each voxel has an initial value of opacity, the method comprising the steps of: calculating a revised value of opacity for each of the voxels in the volume, by the revised value of opacity of a voxel being dependent upon its initial value of opacity and the revised value of opacity of voxels proximate thereto; and calculating an opacity gradient for each of the voxels in the volume using the calculated revised values of opacity for all voxels, wherein the step of calculating a revised value of opacity further comprises the steps of: creating a cell of voxels surrounding each voxel in the volume, wherein all voxels in each cell are arranged into groups so that each voxel in each group of voxels within each cell are positioned one behind the other in a line parallel to the primary direction of light; setting the revised value of opacity of the voxel closest to the source of light in each group of voxels in each cell equal to its initial value of opacity; and setting the revised value of opacity of all other voxels in each group of voxels in each cell equal to the revised value of opacity of an adjacent voxel in the same group of voxels that is closer to the source of light if the revised value of opacity of the closer voxel is equal to or greater than the initial value of opacity of the adjacent other voxel, and setting the revised value of opacity of the adjacent other voxel equal to its initial value of opacity if the revised value of opacity of the closer voxel is less than the initial value of opacity of the adjacent other voxel.