Apparatus and method for volume processing and rendering

An apparatus for performing approximate perspective volumetric ray casting of a three-dimensional (3D) volume dataset, the volume dataset comprising a plurality of discrete voxels stored in a distributed fashion in a plurality of three-dimensional (3D) memory units, each of the voxels having a location lying on a gridpoint in the volume dataset and having voxel data associated therewith, the apparatus comprising:

• an approximating unit, the approximating unit being configured to:
• (a) select viewing and processing parameters which define:
• a viewpoint;
• and
• a view direction;
• (b) calculate a length of the volume dataset between the location of the nearest voxel to the viewpoint and the farthest voxel from the viewpoint, the length being measured along one of:
• (i) a line parallel to the view direction;
• and
• (ii) an axis of the three-dimensional volume dataset that is most parallel to the view direction;
• (c) divide the volume dataset along the measured length into a plurality of slabs, each of the plurality of slabs having an orientation that is perpendicular to the measured length and defines a plane having a position with respect to the viewpoint in three dimensional space;
• (d) generate a perspective projection;
• (e) render each of the plurality of slabs by parallel projection onto a plurality of separate baseplane images;
• (f) texture each of the plurality of images through the perspective projection onto their respective plane;
• and
• (g) blend the plurality of textured images together to form the final image.

An article of manufacture for performing approximate perspective volumetric ray casting of a three-dimensional (3D) volume dataset, the volume dataset comprising a plurality of discrete voxels stored in a distributed fashion in a plurality of three-dimensional (3D) memory units, each of the voxels having a location lying on a gridpoint in the volume dataset and having voxel data associated therewith, the article comprising:

• a computer readable medium containing one or more programs which when executed by a computer implement the steps of:
• (a) selecting viewing and processing parameters which define:
• a viewpoint;
• and
• a view direction;
• (b) calculating a length of the volume dataset between the location of the nearest voxel to the viewpoint and the farthest voxel from the viewpoint, the length being measured along one of:
• (i) a line parallel to the view direction;
• and
• (ii) an axis of the three-dimensional volume dataset that is most parallel to the view direction;
• (c) dividing the volume dataset along the measured length into a plurality of slabs, each of the plurality of slabs having an orientation that is perpendicular to the measured length and defines a plane having a position with respect to the viewpoint in three dimensional space;
• (d) generating a perspective projection;
• (e) rendering each of the plurality of slabs by parallel projection onto a plurality of separate baseplane images;
• (f) texturing each of the plurality of images through the perspective projection onto their respective plane;
• and
• (g) blending the plurality of textured images together to form the final image.