9

Refraction Mapping 1509
2.
In the Material/Map Browser (page 2–1447),
choose the Reflect/Refract map type, and then
click OK.
Adjustingthemap’sStrengthsliderinthe
parent material’s Maps rollout controls how
reflective the m aterial is. At 100 percent, the
material is fully reflective.
To a ss ign a bi tma p a s a ref lection ma p:
1.
In the Maps rollout, click the Map button
labeled Reflection. In the Material/Map
Browser (page 2–1447), double-click Bitmap.
2. In the Bitmap Parameters rollout, click the
Bitmap button.
3. Use the file dialog to choose the bitmap file.
4. Reduce the Reflection map ’s Amount to get the
effect you want.
Refractions are similar to reflections. Bitmaps
simulate reflections, whi le Reflect/Refract maps
generate t hem based on the scene’s background
and geometry.
Refraction Mapping
Material Editor > Standard material > Maps rollout >
Refractio n button
Refractions show the scene or background through a refractive
object.
Yo u c a n s e l e c t a b i t m a p f i l e o r a procedur al map
(page 3–997) such as Reflect/Refract (page 2–1699)
to use for refraction mapping.
Refraction mapping is similar to reflection
mapping. It maps the view onto the surface in
such a way that the image looks like you’re seeing
it throug h the surface, rather than being reflected
off it.
Likeareflectionmap,arefractionmap’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.
Setting the I ndex of Ref raction
Thephysicalpropertiesofrefractiveobjectsoften
distort the image. A special para meter adjusts this
distortion. I t is in the parent material’s Extended
Parameters rollout (page 2–1471).
Index of R efraction—The index of refraction
(IOR) controls how severely the material refracts
transmitted light. Left at 1 .0, the IOR of air, the
object behind the transparent object does not
distort. At 1.5 the object behind distorts greatly
(like a glass m ar ble). At an IOR slig htly less than
1.0, the object reflects along its e dges (like a bubble
seen from under water). Default=1.5 (the IOR of
typical glass).
Common IORs (assuming the camera is in air or a
vacuum) are:
Material IOR Value
Vacuum
1.0 (exactly)
Air
1.0003
Water
1.333
Glass
1.5 to 1.7
Diamond
2.419
In the ph ysical world, the IOR results from the
relative speeds of light through the transparent
material and the medium the eye or the camera is