US 5,847,711 A · Apparatus and method for parallel and perspective real-time volume visualization

Abstract

An apparatus and method for parallel and perspective real-time volume visualization. The method employs ray-slice-sweeping and includes the steps of selecting viewing and processing parameters; initializing a compositing buffer; sampling voxel values from a three dimensional memory buffer onto a current slice of sample points; combining the sample point values with pixels of the compositing buffer along a plurality of interstice ray segments which extend only between the current slice and an adjacent slice associated with the compositing buffer; and repeating the sampling and combining steps by subsequentially sweeping through subsequent slices of sample points parallel to the first processing slice until the last processing slice is reached. Each of the subsequent slices in turn becomes the current slice. The apparatus includes a three dimensional buffer; a pixel bus; a plurality of rendering pipelines; and a control unit. The plurality of rendering pipelines each include a first slice unit; a compositing unit; a two dimensional slice compositing buffer; and a first (preferably bilinear) interpolation unit. Sample point values are combined with pixels of the compositing buffer in the compositing unit along the plurality of interslice ray segments which extend only between a current slice contained in the slice unit and a slice contained in the two-dimensional slice compositing buffer. In the apparatus and method of the present invention, gradients are computed at voxel positions, improving accuracy and allowing for a more compact implementation with less control overhead than prior methods and apparatuses.

Claims37

Dependent claims

A ray-slice-sweeping method for generating a three-dimensional (3-D) volume projection image having a plurality of pixels, said image being generated from a view point, said method utilizing discrete voxels stored in a 3-D buffer, each of said voxels having a location and at least one voxel value associated therewith, said method comprising the steps of:

(a) selecting viewing and processing parameters which define:
said view point;
at least one base plane of said 3-D buffer which is employed for projection purposes;
and
first and last processing slices of said 3-D buffer;
(b) initializing a compositing buffer having a plurality of pixels, each of said pixels having at least color, transparency and position associated therewith;
(c) sampling voxel values from said 3-D buffer onto a current slice of sample points parallel to said first processing slice to provide sample point values, said current slice being said first processing slice during a first execution of step(c);
(d) combining said sample point values with said pixels of said compositing buffer along a plurality of interslice ray segments, said segments extending only between said current slice and an adjacent slice associated with said compositing buffer;
and
(e) repeating steps (c) and (d) by sequentially sweeping through subsequent slices of sample points parallel to said first processing slice until said last processing slice is reached, each of said subsequent slices in turn becoming said current slice.

7 more elements

An apparatus for parallel and perspective real-time volume visualization via ray-slice-sweeping, said apparatus being responsive to viewing and processing parameters which define a view point, said apparatus generating a three-dimensional (3-D) volume projection image from said view point, said image having a plurality of pixels, said apparatus comprising:

(a) a three-dimensional (3-D) buffer which stores a plurality of discrete voxels, each of said voxels having a location and at least one voxel value associated therewith, said three-dimensional buffer including a plurality of memory units, said viewing and processing parameters defining at least one base plane of said 3-D buffer and first and last processing slices of said 3-D buffer;
(b) a pixel bus which provides global horizontal communication;
(c) a plurality of rendering pipelines, each of said rendering pipelines being vertically coupled to both a corresponding one of said plurality of memory units and said pixel bus, each of said rendering pipelines having horizontal communication with at most its two nearest neighbors, each of said rendering pipelines in turn comprising:
(i) at least a first slice unit having an input coupled to said corresponding one of said plurality of memory units and having an output, said slice unit including a current slice of sample points parallel to said first processing slice, said slice unit receiving voxel values from said 3-D buffer onto said sample points to provide sample point values;
(ii) a compositing unit having an input which is coupled to said output of said slice unit and having an output which is coupled to said pixel bus;
(iii) a two-dimensional slice compositing buffer having a plurality of pixels, each of said pixels having at least color, transparency and position associated therewith, said compositing buffer having an input coupled to said output of said compositing unit and having an output coupled to said input of said compositing unit;
and
(iv) a first bilinear interpolation unit having an input coupled to one of:
said output of said compositing buffer;
and
said corresponding one of said plurality of memory units;
said bilinear interpolation unit having an output which is coupled to:
said input of said compositing unit when said input of said bilinear interpolation unit is coupled to said output of said compositing buffer;
and
said input of said at least first slice unit when said input of said bilinear interpolation unit is coupled to said corresponding one of said plurality of memory units;
and
(d) a control unit which initially designates said first processing slice as said current slice and which controls sweeping through subsequent slices of said 3-D buffer as current slices, until said last processing slice is reached;
wherein said sample point values are combined with said pixels of said compositing buffer in said compositing unit, said combination occurring along a plurality of interslice ray segments extending only between said current slice in said slice unit and a slice contained in said 2-D slice compositing buffer.

15 more elements

Dependencies are inferred from the claim text.

Apparatus and method for parallel and perspective real-time volume visualization

Life of this patent

Apparatus and method for parallel and perspective real-time volume visualization

Life of this patent

Abstract

Claims37