3D DIRECT • January 17, 2001

by Eni Oken

Creating realistic texture work has been the Holy Grail of 3D modelers and texture artists, who have a variety methods and tools at their disposal. One method of creating texture imagery, although not very popular, can be extremely convincing. It uses 3D software to generate the image file.

By combining simple geometry and rendering from a front view, with no camera perspective, the artist can extract realistic imagery (see Figure 1) that can be further manipulated in a painting program such as Adobe Photoshop.

The advantages of extracting textures from a 3D model are clear:

1. Custom-made textures can be created following exactly the shape needed to fit odd or organic 3D geometry.
2. Realistic shadows and lighting pre-cast over the texture art can add a dimensional effect to the surface, besides adding realism.
3. Strange and other-worldly texture effects, otherwise impossible to create realistically through normal methods such as scans and photography, can be created.

The disadvantages of extracting textures from a 3D model are also clear:

1. The resulting texture art may have too many shadows that distract from, or conflict with, the lighting of the final 3D scene.
2. Dimensional effects are not always appropriate for specific scenes.
3. It takes a longer time to create and extract textures from models, which can be prohibitive when working within tight deadlines.

Bill Munns, a makeup effects designer for horror feature films such as Swamp Thing (1982), The BeastMaster (1982), and The Return of the Living Dead (1985), entered into the 3D field three years ago, when he first fell in love with Corel Bryce, a 3D program most well known for its ability to create strong landscape imagery based on fractals and procedurals.

One of the most interesting aspects of Munns' work is his preference for generating texture images using 3D software instead of painting programs. He applies the textures generated in Bryce over 3D models created in Discreet 3D Studio MAX v3.1 for his current VRML projects for Jester.com. He regards Bryce not only as a 3D package, but as a powerful painting program, capable of creating incredibly realistic texture imagery: "When you think of a paint tool, you usually think of brushes, canvas, and layers. Painting with 3D objects may seem a bit strange at first, but it is actually a very simple, creative and effective process to 'paint' an image of a texture . . ." Figure 2 shows an example of Munns' powerfully realistic technique: The texture for the horn was entirely generated using a 3D software as the 'painting' program.

Munns offers the following basic guidelines artists should consider while they're painting with 3D:

• The artist must think in terms of basic geometric shapes, such as circular or square, but also keep in mind the 3D curvature of the object and how the light affects that dimensional height.
  
  For example, a texture will be circular in shape if it is extracted from a sphere; but if the sphere is squashed, then the resulting image will be much lighter then when in full curvature (see Figure 3).

• Painting with specularity. The amount of specularity of the material (shader) applied to the geometry can also yield different results. Small specularity will allow for deeper shadows around the edges of the objects. Notice how the curvature of the object in Figure 4 greatly affects the end result caused by specularity.

• Surface erosion and detail. Simple geometry can be greatly enhanced when surface erosion, or even a displacement map, is applied. This allows for the perimeter of the final texture image to have more intricacy and detail. Two identical shapes, spheres for example, can have different levels of erosion and intricacy, creating different results (see Figure 5).