Dirt Mask Creation

I created a dirt mask, which is used to switch between the relative_clean and dirty texture maps. This mask needs to be procedural in nature because when I start to distribute the various buildings, the mask automatically adjusts to show continuity.

The logic behind the mask is to mix various procedural noise patterns within a clamped real-time ambient occlusion. You can use any noise patterns that you like so long as it does not look too uniform. I do recommend mixing various noise types to get the final look. You can see the dirt mask applied to the geo set in Fig.06.


To show the automatic adjustment of the dirt mask, I took a small geo "B04” and applied the mask to it (Fig.07). You can see the variation in the noise pattern.


I duplicated B04 (Instance) and rotated it 90 degrees. You can see that the Dirt mask automatically creates a rim of pattern where the two geometry blocks meet (Fig.08).


If I move the new instance in any direction the mask automatically adjusts to the position. Note that each movement creates a unique pattern (Fig.09 – 10).

Texturing

I started by first establishing a look for the relative_clean shader. The process for it was quite simple. You can go about it in one of two ways:

1. Using Layered Texture (Maya)

• Create a new file node
• Link the required texture file to it
• Link the newly created file node into the layered texture.

2. Using Composite Map (3ds Max)

• Click on Create a New Layer
• Click on the map/node slot and choose Bitmap from the options
• Browse and link to the texture file.

Relative Clean Shader