Transfer Maps In Maya
Transfer maps allow you to take one model and make another model look like that model through normal maps, displacement maps and bump maps. If you don't know what those are, you should read this tutorial on normal maps, displacement maps and bump maps. This tutorial will cover creating a normal map using the transfer maps tool in Maya.
Unlike other features in Maya, transfer maps allow
both the target mesh (this is the mesh that the transfer map will apply
the normal map of the other object to) and the source mesh (this is the
geometry that Maya generates the normal maps from) to have completely
different geometry, different UV maps, and different polygon
resolution. For this tutorial we're going to be using a high polygon
torus with some deforming, and a low polygon torus. You can download
the two models here.
The whole point of this is to make our low polygon torus look like the
high polygon torus without increasing the low polygons geometry.
Setting Up The Transfer
First select trans_torus1 and on the rendering menu set go to lighting/shading>transfer maps... This will open the transfer maps window.
Since you selected the low poly torus, it will automatically become the target mesh. You can have multiple target meshes. If you didn't select the mesh when you first opened the transfer maps editor, you can load it by selecting it and, in the transfer maps editor, clicking Add Selected. If you want to remove a target mesh, select it and go to Remove Selected. Make sure the output UV set is set to the current UV set for the model. If you're using the example file, that won't be a problem.
Go down to the source mesh tag and open it. By default its set to All Other Meshes (geometry). This doesn't work if you have other items in the scene that you don't want to be used as a source mesh. To fix this, select the source mesh, in our case its trans_torus2, and click Add Selected. Now, only that object is a source mesh. If you wanted to have every object but the selected object a source mesh, click Add Unselected. To remove a source mesh, select it and hit Remove Selected. You can right click on an object in this list and select it or remove it from the list.
One transfer map can output more than one type of map. By default its set to normals map. It can create normal, displacement, diffuser, shaded, alpha, ambient (ambient occlusion - I've written a tutorial on ambiance occlusionhere), and custom (you can use a custom shader to be used as a transfer map).
Transfer maps can create more than one map at a time. Even though we're only using normals maps, click on the displacement map icon. It will add displacement map options for the output section.
To remove the displacement map option, click Remove Map. Now what's left is the normal map's options that are created by default. You can set the location of the map file on your hard drive by using the file format (avoid using Jpeg) the option to include ore not include materials. The map space (leave it at Tangent space) and the option to use common (global) Maya settings. If you were to uncheck this, you could change the maps width and height in pixels for this normals map.
Connect output map
Connect maps to shader - This will allow Maya to automatically set up connections to the map files to the targets meshes shader.
Maya common output
Map width/ height
- This attribute sets the width and height in pixels of the texture
map. The option to keep the aspect ratio is best left on. The higher
the resolution of the map, the more detail we'll be able to transfer.
But it will take longer for the transfer map to be created and it will
take longer for the transfer map to render.