Graphics Reference
In-Depth Information
Height
-
Bump: A grayscale map used to defi ne surface height differences. Bump
maps do not affect the actual height of vertices, so it does not affect the edges
of an object it is attached to.
-
Displacement: A displacement map is similar to a bump map but it creates
displaced vertices based on the map. This does affect the boundary edges of
the object it is attached to.
-
Normals: Normal maps solve a problem inherent to bump and displacement
maps. Instead of translating vertices in the height axis only, a normal map records
vectors across the surface of an object. This produces a high level of surface
detail with the appearance of height and face orientation changes at a low cost.
• Label: Label textures are assigned to shaders that are then layered onto other
shaders. This allows the same label shader to be applied to multiple different
shaders. It also allows an object that only requires texture for the label itself, such
as a car, to use an untextured shader for most of its surface area.
11.5
Textures
11.5.1
Introduction
Textures are used to convey changes within or across polygons. If the values were
fi xed for an entire object, such as a piece of clean red plastic, a texture map for the
color channel would be unnecessary. With a texture map, instead of using only
the vertices or faces of the model as reference points, you can modify renderable
qualities of your object within a face by using the pixels of a map attached to it.
Textures add a variety of different types of information to your model; color, bump,
specularity, subsurface scattering, displacement, normals, fur, glow, and more. It is
important to keep this in mind before you begin the job of texturing any model.
Unless you think of your map as information, it is very easy to put the wrong type
of information into your map, and reduce the quality of your fi nal rendered output.
11.5.2
Monitor Calibration
In fi lm visual effects (VFX) studios, all monitors are calibrated frequently. In game
studios, it almost never happens, and some studios don't do it at all. If your monitor
is not calibrated (and if you aren't sure, then it isn't) then you cannot trust the colors
you see on your screen. This is true even if you have a brand new, straight from the
factory, never adjusted monitor. As I type this, I have two such monitors in front of
me, and images on one, when transferred to the other, do not match. This means that
at least one is wrong, but more likely both are. For photo editing, a color-calibrated
monitor should be used instead.
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