This Blender video demonstrates how to apply surface cracks to an object. Blender version 2.74 was used for this tutorial. This video shows techniques that may be helpful to intermediate and advanced users.
00:16 Setup described.
01:32 Noise Texture added.
02:27 Subtract math nodes added. This converts the noise texture to black and white and centers it around zero.
03:24 Maximum node added. This produces black lines that can be used for the cracks.
03:59 Minimum node added. This filters out everything except the black lines.
04:24 Multiply node added. This lightens things up.
04:43 Emission shader is deleted and Mix shader is reconnected.
04:53 Multiply node connected to Displacement input to produce cracks on the sphere.
05:11 Noise Texture Detail value adjusted to produce jagged edges.
05:25 Nodes added to give cracks a diffuse material.
07:05 Node adjustments explained.
07:46 Positioning of cracks explained.