Comparison of pre-shaded (left) and pre-integrated (right) volume rendering using a random transfer function (high frequencies). Note, that in contrast to the left, no details of the transfer function are lost on the right. Find the random transfer function here. 32 textured slices were used for both images (spherical harmonic function, volume resolution: 32x32x32 voxels) ! Post-Classification shading on an Octane MXE also shows much detail, but the annular structures change when rotating the volume. When rotating the volume using pre-integrated volume rendering, the annular structures remain nice and smooth.

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Post-Classification shading on SGI Octane MXE:

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Used transfer function and dependent texture:

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Comparison of post-classification shading (left) and pre-integrated volume rendering (right) with the inner ear data set using 128 slices. Note, that post-classification shading shows slice artifacts due to the lack of trilinear interpolation. Pre-integrated volume rendering achieves the full quality without the need for additional trilinear interpolated slices, thus saving rasterization power.

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Press key 'j' in the demo renderer to switch between pre-integrated and post-classification shading.
Press key 'k' to build a random transfer function with high frequencies.


Isosurface of a micro CT scan from a metal foam with 512x512x106 voxels resolution, rendered at 1280x1024 pixels. Find the data set on Christof's homepage.

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Several new high resolution images

10 isosurfaces of the ell data set visualized in a single rendering pass. Note, that the complexity and performance of pre-integrated isosurface visualization is independent to the number of isosurfaces.

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Volume shaded visualization of the ell data set with a random transfer function.

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Volume shaded rendering of convection flow in the earth's crust. Data set consists of 30 time steps and can be found here.


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New demo with multiple differently colored isosurfaces (d/l 1278KB)

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Two new mathematical data sets (find the data sets here)

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Updated the demo renderer. Transfer function panel works now much better. Download the updated demo here.


Visualization of the visible female data set at 2-3 fps on a low-cost PC. Data was resampled at 256x256x512 voxels. Note, that the isovalue can be changed interactively to reveal skin or bones.

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Demo renderer 1.61 now available for Linux and Windows version updated to version 1.61. This version allows much faster change of isovalue. Download it here.


Isosurfaces can also be produced with volume shading and transfer function peaks. This allows for smooth transitions from transparent to opaque when approaching the surface.

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Version 1.7 of the pre-integrated volume renderer now allows weigthing of three volumes on the fly. We use this weighting to apply a low-frequency and high-frequency perlin noise volume to the original volume. New version of renderer will be available for download soon ...

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Klaus Engel, 30. May 2001