Several illustrative techniques were implemented using GLSL:
- Toon-shading
- Cool-to-Warm (Gooch)
- Drawing (several contour-techniques combined to simulate a sketch)
- Gradient based contours
- Curvature-controlled contours
The techniques also has several options and variations (gooch with/without splashback, etc..)

A normal direct volume rendering using Blinn-Phong shading.

Changed Blinn-Phong shading to cartoon-shading.

Turned on curvature-controlled contours.

Also turned on gradient-based contours with low exponent for a bit more shading (depth-feeling).

Gooch cool-to-warm shading.

Gooch with curvature-controlled contours.

Gooch with curvature-controlled contours and splashback (for more depth).

A technique sometimes used in photography, by placing two strobes at opposite sides gelled with cool and warm gel, where the light meet it will be combined to white light..