Rocks are really simple. The figure above shows my particular technique.
The top left is just a generic rock shape crafted from a Sphere3D, with the default Fast Render material applied. I used this same rock for all of the rocks along the right hand column – just turned them different ways.
The top center rock is the same rock, but with a modified version of Noise Pattern 1 material applied. The diffusion graph is somewhat inverted and the value lowered. The noise graph is all full of spikes, with the noise radius increased to 60. Color Bump is at -4 and specularity is only 10. Material can plainly make a huge difference!
The top right rock is exactly the same, but with a hint of color added. The reason that the pattern is a little different is that materials create procedural textures, which change based on each pixol’s XYZ coordinates. As a result, a material’s appearance can alter radically across the canvas, while still maintaining the same properties.
The bottom rock is exactly the same as all the others, but enlarged and with a seamless photographic texture applied. The material’s color bump responds to the texture, and the noise is also visible through it. In other words, materials work with the texture to create very impressive results! This particular aspect of ZBrush is part of why the rendering engine is so darned good. Unfortunately, a lot of artists forget that the texture and material work together on this level. Not only can noise be used to bring extra realism to a photographic texture, it can also disguise the fact that a texture is actually tiling (the noise acts as a texture within the texture).
In fact, I can hardly wait for when ZBrush has the S3 and S4 material channels available – imagine an object with 2 or 3 types of noise applied to it, in addition to a texture!
If I had wanted to, I could also have created a seamless texture of my own directly on the canvas. Tilde-Scrolling (holding down the ~ key and dragging the canvas) allows you to always paint at the center of the canvas, then bring the edges to the center to paint them. The end result is a seamless pattern. If you start with a base color, then use lots of variations in color and alpha settings on the simple brush, you can create some very remarkable textures very quickly. When you like what you have, you’d use the MRGBZGrabber to pick the texture up from the canvas, then clear the layer.
Whether you decided to use a photographic texture or a self made one will depend on your needs at the time, and your resources.
Hope that helps!
Wow