Ray-slice-sweeping is a plane sweep algorithm for volume rendering, The compositing buffer sweeps through the volume and combines the accumulated image with the new slice of just-projected voxels. The image combination is guided by sight rays from the view point through every voxel of the new slice. Cube-.#L is a volume rendering architecture which employs a ray-slice-sweeping algorithm. It improves the Cube-4 architecture in three ways. First, during perspective projection all voxels of the dataset contribute to the rendering. Second, it computes gradients at the voxel positions which improves accuracy and allows a more compact implementation, Third, Cube-AL has less control overhead than Cube-C
IntroductionVolume visualization is a method of extracting information from volumetric datasets through the use of interactive graphics and imaging, and is concerned with the representation, manipulation and rendering of these datasets [5]. Most commonly, the data represents a continuous 3D function sampled on a ree;ular, rectilinear 3D grid of volume elements called uoxels. Depending on this 3D function (mathematical, MRI, CT, ultrasound, etc.) voxels accordingly represent function value, density, absorption, etc. There are many different approaches for rendering images from these volume datasets. Volume rendering includes only those techniques in which the image generation does not use any intermediate surface representations of the sampled data. These techniques fall into four groups: object-order, image-order, and hybrid algorithms as well as domain methods.l ingmar&s.sunysb.edu, Permission IO runke dij$nl/Jlnrd copies ofnll or part of this tnnterinl for pursosnl or clnssroom 11s~ is gmakd without Re provided thnt tke copies nre not mnde or disM.Wcd hr prolil or conunercinl advantage, the copyright nolice, ~lle title of he publication nad ils date appar, and nolice is given tl~nt copyriSllt is by penkion ofthe ACM. Inc. To copy otherwise, IO republish, IO post on servr'rs or to redislriibute to lists, requires specific penuirsion and/or Ii'e 1997 SlG(iR.4 PH/Euqtwphics Workhop CopyrigM I937 ACM 0.89791.36l-0/37/S..%3.50Object-order algorithms compute each voxel contribution to all affected image pixels in object-storage order (e.g., splat&g [18]). Image-order algorithms compute each pixel color in image scan line order. For each pixel, a ray is cast into the volume, and all the voxels in the neighborhood of the ray are processed and composited to generate a color value for the pixel (e.g., ray-casting [7], volumetric raytracing [15]). These algorithms usually deliver higher image quality than object-order algorithms, but they also require more computation and tend to access each voxel multiple times.Hybrid algorithms combine object storage-order voxel access with image scan line processing order (e.g., slice transformation [1], cell-by-cell processing [16], template-based volume viewing [19], shear warp [6]). Good hybrid algorithms combine the high image quality of image-order algorithms with the efficient data acces...