This section introduces a second form of material definition, that of procedural textures.

A common problem that occurs with standard materials is that of inconsistencies when the material "wraps around" a solid. Take, for example, a wood material, applied to a sphere, slab and cylinder:

• The sphere looks like a beach ball, with the woodgrains "bunched up" unnaturally at the "poles."
• Grains, displayed on the slab and cylinder, do not align at the edges where surfaces meet.
  
  
  

While rotating the pattern 90° may reduce the problems (particularly with the sphere), making them less noticeable, that is a work-around and not a solution. These mismatches are inherent with the method used to apply the material. It is similar to applying a laminate or wallpaper to a surface. That is, the same pattern (material definition) is applied separately to each surface of each solid. Additionally, on a large area, tiling occurs where the image used for the material is repeated.

These problems can be overcome with procedural textures, which produce natural looking materials.