Important Materials Theory - Photographic Rendering with V-Ray for SketchUp - page 245

The importance of realistic color values
As interesting as the facts regarding the way things work may be, the points we have
been discussing here are far from just academic in nature. The creation of realistic
materials in a believable and consistent manner inside our render engine will depend
greatly upon our ability to put all of this interesting information to some kind of prac-
tical use.
For instance, when we look more closely at the wavelengths of light seen in the world
around us, the insights we gain can help us avoid the kind of mistakes that newer
render artists may be prone to, a typical example of which would be the tendency
towards using colors in materials that just do not (or at least very rarely) exist in the
real world. What I mean by that are fully saturated (255) color values that, for obvi-
ous reasons, look unnatural in a finished render. The extra vibrancy and saturation
they give can often cause a surface to almost look as if it is glowing.
Note
Such over-saturation has for decades been associated with artificial imaging pro-
cesses such as technicolor, a film process used in a very obvious manner to cre-
ate the hyper-real Oz sequences in the 1939 film, The Wizard of Oz .
To avoid creating unnatural colors in a material, we typically need to keep saturation
levels below 85 percent. When using the HSV model, this is as simple as keeping
the saturation value at 218 or lower.
Another common mistake is to create materials that have unnaturally high reflect-
ance or diffuse light bounce properties. Once reflectance (determined by the bright-
ness of the diffuse color) passes the 80 percent mark in a material, we will typically
find ourselves suffering from troublesome hotspot and color-bleed problems in our
renders. Once introduced, these issues can be extremely problematic to deal with,
especially if we are not aware of the reasons why the problems have started to occur
in the first place.
The best way to deal with such issues of course is to avoid introducing them in the
first place. This can be done by taking time to carefully consider the brightness or
value of the colors we are using and the effect that this will have once lights and