<udim>

Image shader with the <udim> tag

 

UDIM values are a way of representing the integer coordinates of a texture, from the coordinates of its bottom-left corner in UV space. This way, multiple textures can be used to cover a model, rather than a single, much larger, texture.

A cylinder with its side in u0,v0, base in u0,v1, and top in u0,v2

 

It is a 4 digit number starting at 1001, created using the formula, 1001 + u + (10 * v)

In the example above the side would be 1001, base 1002, and top 1003.

To use this method in your file inputs, use the <udim> tag in the file name, which is then replaced with the appropriate number.

texture.<udim>.exr will be read as texture.1001.exr when looked up for rendering.

Check out Ben Neall's page for a clear description of UDIM numbering.

 

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