Graphics Reference
In-Depth Information
duplicated models in your scene without the tremendous decrease in render speed that has been previously
associated with such scale and complexity. Replicators are covered Chapter 9.
Using UV Maps
Procedural textures are extraordinarily powerful. They enable you to create many types of materials and ser-
vices, but they are limited because the placement of color values is based on mathematical algorithms that
cannot be precisely controlled by the user. To make more-exact textures, it is often necessary to use images
as textures. Unfortunately, images are two-dimensional, and their placement in three-dimensional space can
be problematic because many models are much more complex than simple cubes, spheres, or cylinders. To
gain precise control of two-dimensional texture placement in three-dimensional space, 3D models must be
flattened into two dimensions. The creation of a two-dimensional representation of a three-dimensional form
produces what is known as a
UV map
.
UV maps enable you to place image-based textures onto your models, gain additional control over the
placement of procedural textures, and open up options for painting and sculpting directly on the surface of
your models. Geometry created with basic shapes will automatically have an associated UV map. Simple
edits to this geometry will not damage the UV. After extensive modeling processes are carried out on a mod-
el, the original UV map will lose its integrity and will need to be either repaired or replaced. Geometry that
is created from scratch will often have no associated UV at all, in which case one will need to be created.
The UV tab gives access to all of the tools necessary for creating clean and usable UV maps. The basic
idea behind the creation of these maps is similar to removing the wrapping from a package. This can be done
via simple projection methods (that is, planar, spherical, or cubic) or by selecting edges that act as seams,
where the model can be separated and unwrapped and flattened into two-dimensional space. After an initial
UV unwrap has been performed, you can use various tools for aligning the individual pieces, edges, and
vertices as well as optimizing the placement of these pieces. The creation of UVs can be a complex and
daunting process, but it is essential to many aspects of the design process. The exercise at the end of this
chapter includes a simple introduction to this technique. A more complex look at UV creation is featured
Chapter 6.
Creating Image-Based Textures
Image-based textures will grant you increased artistic freedom as well as the ability to use photographs as
textures. While images can be placed with simple projection methods, it is typically necessary to create UV
maps for proper placement. Many times 3D models are created to showcase packaging, label design, or oth-
er two-dimensional pieces of work. In these cases, it is imperative for these images to appear on the surface
of 3D models. Using image-based textures enables you to use your creative prowess in 2D design and show-
case it in realistic 3D scenes, on 3D models, and in compelling environments.
In addition to the ability to incorporate graphic designs into 3D scenes, the use of photographic image-
based textures can heighten the realism and believability of a 3D scene. Photographic textures can be used
directly to color objects or to add variations in reflectivity, shininess, transparency, and even surface contour.
Often, these variations can be subtle, but they allow for the inclusion of details that would be difficult, time-
consuming, or even impossible to create with procedural textures or by hand.
Figure 3-20
shows an example
of a simple 3D scene that utilizes photographic textures and painted textures to create the final look.
