Eliminating Popping Artifacts in Sheet Buffer-Based Splatting

Splatting is a fast volume rendering algorithm which achieves its speed by projecting voxels in the form of pre-integrated interpolation kernels, or splats. Presently, two main variants of the splatting algorithm exist: (i) the original method, in which all splats are composited back-to-front, and (ii) the sheet-buffer method, in which the splats are added in cache-sheets, aligned with the volume face most parallel to the image plane, which are subsequently composited back-to-front. The former method is prone to cause bleeding artifacts from hidden objects, while the latter method reduces bleeding, but causes very visible color popping artifacts when the orientation of the compositing sheets changes suddenly as the image screen becomes more parallel to another volume face.

We present a new variant of the splatting algorithm in which the compositing sheets are always parallel to the image plane, eliminating the condition for popping, while maintaining the insensitivity to color bleeding. This enables pleasing animated viewing of volumetric objects without temporal color and lighting discontinuities. The method uses a hierarchy of partial splats and employs an efficient list-based volume traversal scheme for fast splat access. It also offers more accuracy for perspective splatting as the decomposition of the individual splats facilitates a better approximation to the diverging nature of the rays that traverse the splatting kernels.

Here is the paper, that was presented at the 1998 IEEE Visualization conference, pp. 239-245, and here is the slide show of the talk.

IMAGES AND MOVIES (click on image titles to see quicktime animation):

Traditional axis-aligned sheet-buffer method	New image-aligned sheet-buffer method

Cube	Cube

UNC MRI dataset	UNC MRI dataset

Segmented MRI brain	Segmented MRI brain

Nerve cell obtained with confocal microscope, aspect ratio 1 x 1 x 5	Nerve cell obtained with confocal microscope, aspect ratio 1 x 1 x 5

Bonus movie:(Click here) for a full rotation around the nerve cell, rendered with the new, image-aligned sheet-buffer splatting method

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