Method and apparatus for directly generating three-dimensional images from voxel data with dividing image generating processes and utilizing parallel processes

Claim 1

A high-speed 3D image generating apparatus for generating and displaying a three-dimensional (3D) image of a display object arranged as an object of image generation in a 3D space and projected onto a projection plane according to volume data representing a distribution of a visual attribute at each position of the 3D space and rendering parameters determining characteristics of the image to be displayed, comprising: volume data acquiring means for acquiring the volume data; volume data storage means for storing therein the acquired volume data; input means for inputting the rendering parameters; 3D image generation process means, including a plurality of processors, for estimating a quantity of calculations necessary for the creation process of the 3D image according to a portion of the volume data stored in said volume data storage means, subdividing the generation process into sub-processes and thereby substantially equalizing the quantities of calculations respectively allocated to the plural processors, concurrently executing the sub-processes by the plural processors according to the volume data stored in said volume data storage means and the rendering parameters input thereto, and generating a 3D image; and image output means for visualizing the generated 3D image, wherein the 3D image generation process means sequentially performs the steps of: resampling the voxel value of the volume data representing the 3D space in a normal direction beginning at a first pixel group arranged in the projection plane with an interval larger than a pixel interval of pixels for which the 3D image generation process is to be executed on the projection plane, the resampling interval being larger than the pixel interval, deciding a first position group including a position at which the voxel value attained as a result of the resampling step exceeds a preset threshold value and a position which is on the normal line and which are least apart from the projection plane on the normal line, deciding a second position group including a position on a normal line passing each pixel of a second pixel group including pixels other than those of the first pixel group and a position interpolated according to positions of the first position group associated with one or more pixels of the first pixel group in the periphery of the pertinent pixel, and subdividing voxel data of voxels at respective positions of the first and second position groups into as many subdata items as there are processors.