Samples are located on planes perpendicular to the view direction.

Samples are located on planes perpendicular to one axis of the volume.

Samples are located on shells aligned with the volume's internal "boundary".

Each ray begins sampling at the first intersected voxel that has an alpha value > opacityThreshold.

Similar to BOUNDARY_ALIGNED but uses a cubic interpolation to compute the boundary, giving smoother results when using SoVolumeRenderingQuality.deferredLighting.

When using linear interpolation and deferred lighting, BOUNDARY_ALIGNED can generate "flat shading" due to linear interpolation between voxels. SMOOTH_BOUNDARY_ALIGNED will generate a smooth shading using a cubic interpolation to find the volume's boundary and use a linear interpolation for the rest of volume. This is a good compromise between result and performances of a full tricubic interpolation. Please refer to SoVolumeRenderingQuality.deferredLighting and SoVolumeShape.interpolation for details. LIMITATIONS SMOOTH_BOUNDARY_ALIGNED is not supported in the following case:

• With isosurface rendering

• When using gradients computed from the voxel values (SoVolumeRenderingQuality.lighting for instance).

• When using SoUniformGridClipping nodes. In one of the above case, BOUNDARY_ALIGNED is used.

  Possibly heavy GPU usage