Refractions show the scene or background behind the refractive object
Allows you to select a bitmap file or procedural map to use as a refraction map.
A refraction map is similar to a reflection map, only it maps the view onto the surface so that the image looks like you’re seeing it through the surface rather than being reflected off it.
Like a reflection map, a refraction map’s orientation is locked to the view rather than to the object. That is, as you move or rotate the object, the position of the refracted image remains fixed.
The physical properties of refractive objects often distort the image. 3DS MAX has a special parameter to adjust this distortion. It is in the parent material’s Extended Parameters rollout.
Refract Map/Raytrace IOR: IOR stands for index of refraction. An index of 1.0 is comparable to air, and does not refract. At values greater than 1.0, the refraction tends to become more convex; at values less than 1.0, the refraction tends to become more concave. Default = 1.5 (the index of refraction of typical glass).
Tip: The Reflect/Refract map type used as a Refraction map doesn’t effectively model a material surrounding an object, such as a pencil in a glass of water. For this effect, use either the Thin Wall Refraction or the Raytrace map type.
Automatic refraction overrides the material’s Opacity settings. At 100 per cent strength, the material is extremely refractive. At 0 per cent strength, the material does not refract, but it is fully transparent and the filter color tints objects behind objects assigned this material.
Now choose the bitmap as you would choose a diffuse map. For bitmapped refractions, you don't necessarily want to reduce the map strength.
Reflect/Refract maps have specific parameters that are described in the following topic.