Creating Believable Materials - Photographic Rendering with V-Ray for SketchUp - page 201

Adding reflections to our floor material
Perhaps the first thing we should point out is just how the reflection controls work in
both the Standard material and the newer V-Ray Material. Essentially, V-Ray makes
use of greyscale values as a means of controlling the level or strength of reflections
found in a material. Black equals no reflectivity, while white adds full reflectivity to the
object, creating mirror like surfaces.
If we take a look in the General section of the Reflection rollout, we can see that
the Reflection parameter already has a map placed into the map slot by default. If
we click on the button to open up the V-Ray texture editor window, we can see that
this is in fact a TexFresnel map as seen in the following screenshot:
This map, just like the main reflection control, uses greyscale values as a means
of determining the reflection levels. In this instance, though, there are two color
swatches, one (the top one) for controlling the Perpendicular or glancing angle
levels, while the other, Parallel , handles reflectivity on areas of the geometry that are
facing directly toward the camera.
We also need to note that the reflection levels set by the greyscale values here will in
turn be affected or modified by the IOR and Refract IOR settings that the TexFres-
nel map also uses.