OpenGL "nearest neighbor" interpolation.

OpenGL linear interpolation (Default).

This implies bi-linear interpolation for 2D textures (e.g. SoOrthoSlice, SoObliqueSlice, SoVolumeSkin, SoFenceSlice) and tri-linear interpolation for 3D textures (SoVolumeRender, SoVolumeGeometry).

Tri-linear interpolation for SoObliqueSlice.

Tri-linear interpolation is used when extracting the 2D texture that will be applied to the slice, providing better image quality. Same as LINEAR for other nodes. NOTE: enumeration value available since Open Inventor 6.0

Multi-sample interpolation for slice shapes.

Interpolates data values using 12 samples around the voxel. This provides much higher image quality and specifically avoids rendering artifacts due to bi-linear interpolation. Only supported for 2D texture shapes (e.g. SoOrthoSlice, SoObliqueSlice, SoVolumeSkin, SoFenceSlice). Same as LINEAR for other nodes. NOTE: enumeration value available since Open Inventor 7.0

Cubic interpolation.

This implies bi-cubic interpolation for 2D textures (e.g. SoOrthoSlice, SoObliqueSlice, SoVolumeSkin, SoFenceSlice) and tri-cubic interpolation for 3D textures (SoVolumeRender, SoVolumeGeometry). It gives smoother results, especially for volume rendering.

Linear interpolation	Cubic interpolation

Heavy GPU usage. Primarily useful for still image rendering.

SoInteractiveComplexity icplx = new SoInteractiveComplexity();
icplx.fieldSettings[0] = "SoVolumeRender interpolation LINEAR CUBIC";
root.AddChild(icplx);

NOTE: enumeration value available since Open Inventor 9.3