Graphics Reference
In-Depth Information
As with the previous photographic textures, this image set includes bump and specular images. Placing
the three photographs into their respective channels hints at the look of the finished material, but better al-
location of the image maps is required to create the finished product. One of the main reasons for using
photographic reference images is the scale of detail. Because the main details in a material such as this have
a relatively large scale (individual rocks in this case), the depth created by a bump map is insufficient. A
displacement map is more appropriate for this type of material creation. Simply changing the bump layer to
displacement will not complete the material alone. The intensity of contrast in the bump layer will produce
a displacement map that looks very rough and takes a long time to render because of the massive number
of polygons created. Remember, while bump maps give the illusion of details, displacement maps actually
create geometry. Left unchecked, displacement maps can exponentially increase the polygon count of your
scene and your render times. At default settings, the rock displacement map greatly increases render time
and results in a very noisy surface, as shown in
Figure 11-15
.
Figure 11-15:
Using a bump map directly as a displacement can produce a rough and slow render.
