Can I use a texture as hair density map?

Question

I would like to use a texture as density map because it can be much more precise than a vertex group, is it possible? In Cycles render.

Answer 1

In Cycles select the mesh, give it a material, then go the Particles header and add a new texture in the Textures panel.

Prepare your black and white density map. Here's mine:

Next go to the Texture header, add a new texture (Image or Movie) and check the Density checkbox in the Influence panel. Note: I also checked the Lenght checkbox to make the render look more clear.

In Blender Internal you can do it the same way. After giving the mesh a material and the particle system you go to the Texture header-->Particle Texture button, load your texture as Image or Movie and select what kind of influence on particles it should have.