Volume Rendering CPU VS GPU

Operating system: Windows 10
Slicer version: 2020-03-06
Expected behavior: better rendering
Actual behavior: Unknown

In our spine simulation project, due to issue on speed of burring. We are trying to switch from surface rendering to volume rendering for the visualization of the label map model. A volume rendering performance in the laptop Intel-5 without GPU is shown in figure (a). Quality was selected as maximum and interpolation as linear. The same rendered volume was saved as mrb file and loaded into the Intel - I9 computer with GPU GTX 1600 super. (some experiments were also done by directly performing volume rendering of the label map model). Figure (b)

According to our expectation, the quality and smoothness of rendered volume should be superior in the GPU based computer. But based on the experiments, the quality and smoothness of rendered volume in CPU based computer without GPU looks superior. Is there any explanations or suggestions, what might be the actual reason? How can I improve volume rendering properties, beside the properties mentioned in volume rendering module ?

It would be a great helpful for our project.

Thank You !!

Raj Kumar Ranabhat

CPU volume rendering can change the order of interpolation and mapping, which can result in slightly higher quality images with CPU volume rendering. However, you can drastically improve rendering quality by blurring the edge of the volume (e.g., rescale the exported labelmap to range 0-255 using Simple Filters module RescaleIntensityImageFilter and apply slight Gaussian blur image filter).

Left: volume rendering of labelmap volume.
Right: volume rendering of the same labelmap volume after rescaling and blurring

You simulate burring, by subtracting a precomputed volume (with soft edges) from the volume-rendered image.

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