No Shade - has none of the parameters shown here, IsoSurface object will appear as a featureless blob. Should be used when using Maximum Value or Maximum Opacity. Diffuse Coefficient - how strongly the surface will appear illuminated by diffuse light. Specular Coefficient - how much of mirror like appearance the surface will have. Specular power - how sharp the specular reflection will be.
Higher number gives a sharper, smaller area of specular reflection on a convex surface.
Lower number gives the surface a more matte appearance. Transmit Coefficient - how transparent the object is. Transmissitivity - this is the fraction of light that is blocked per unit length along a ray passing through the volume. Index of refraction - how the light is refracted through a transparent object. There can only be one cut per object, and the only type is Simple Box Cut in version 2.1 of VolVIs.