ambient occlusion

Inverted occlusion in 3D Max by Xuan Prada

People asked me for a step by step installation and usage of Binary Alchemy Color Ray Length shader in 3D Max.
Here we go.


  • Download BA Shaders for 3D Max.
  • Copy .dll files here -> “3ds Max 2010\mentalray\shaders_3rdparty\shaders”
  • Copy .mi files here -> “3ds Max 2010\mentalray\shaders_3rdparty\include”
  • Edit “3rdparty.mi” located here -> 3ds Max 2010\mentalray\shaders_3rdparty
  • Your “3rdparty.mi” must be something like this.


  • Create a matte/shadow shader and uncheck “receive shadows” and “use ambient occlusion”.
  • In the “camera mapped background” input, connect a “BA_color_raylength” shader.
  • Play with the “spread” to control the behaviour of the occlusion.
  • Once rendered you’ll have something similar to this.
  • Mix the “BA_color_raylength” with procedural maps or bitmaps to improve the result.

Edit: The most important parameters to play with are “spread” and “far output”.

Improved dirt maps by Xuan Prada

When we start the task of texturing props, environments or characters, one of the first steps we accomplish after completing the UV Mapping, is baking different texture maps or procedural maps (or any other type) to a later use them as a base point to paint our textures.
Probably the most baked map is the ambient occlusion, to reach a base of dirt in logic areas which we will modify in Photohop, BodyPaint or Mudbox.

In my own experience I think that occlusion bakes are incredibly useful but a little bit boring.
Find below a simple method to create a more funny and live ambient occlusion bakes.

  • Using a costant shader or any other which are not affected by lighting, we mix using mix2colors, blendColors or Mixer.
  • In the channel 1 of the mix we use a map. Can be procedural or bitmap. In this example I’m using a tiled bitmap.
  • In the channel 2 of the mix we use a white color.
  • In the mask of the mix we use an ambient occlusion.

With this method we achieve that the bitmaps or procedural maps get masked by the occlusion, creating dirt on the logical and less exposed areas, but with the variation given by the map.
The keys to reach good results are the configuration of the occlusion and the quality of the maps.

This is the scene that I'm using for this example.

Regular ambient occlusion render.

Ambient occlusion render mixed with bitmap textures.

Dirt shader in Softimage.

Dirt shader in Maya.

Dirt shader in Max part 1/2

Dirt shader in Max part 2/2