OpenGL "nearest neighbor" interpolation.

OpenGL linear interpolation (Default).

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

Tri-linear interpolation for OIV.VolumeViz.Nodes.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
Enum 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. OIV.VolumeViz.Nodes.SoOrthoSlice, OIV.VolumeViz.Nodes.SoObliqueSlice, OIV.VolumeViz.Nodes.SoVolumeSkin, OIV.VolumeViz.Nodes.SoFenceSlice). Same as LINEAR for other nodes.

Note
Enum available since Open Inventor 7.0

Cubic interpolation.

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

Linear interpolation	Cubic interpolation

Caution
Heavy GPU usage. Primarily useful for still image rendering.

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

Note
Enum available since Open Inventor 9.3