You need good UV unwrapping of your model for good results. UV mapping stands for the technique used to 'wrap' a 2D image texture onto a 3D mesh. If you've painted texture maps in the past, you'll know that bad UV mapping coordinates can make the texturing process painful.
Firstly you should have a clean mesh, meaning that it is better if your mesh has been created with all quadrangular faces, and has no extra vertices. When you're happy with your mesh, you are ready for the next step: UV unwrapping.
It is not difficult to grasp UV unwrapping – you just need to know where to place your UV seams. It is usually best to place seams where real clothing has seams. For instance, a shirt is made up of panels of cloth sewn together. So place your UV seams where those panels of cloth meet. This method is more realistic and it reduces the pain of hiding seams.
If the seams are not placed in a realistic location, you will need to make sure you can paint textures in a way that the seams will not be visible. I use the Roadkill professional plug-in for Maya. It automatically lays out UV co-ordinates and minimises distortion in just few clicks.
01. Run the plug-in
Firstly you'll need to run the plug-in by typing Roadkill in the Maya MEL editor, and press [Enter]. Now select your model and check all boxes in Road Kill then press unwrap.
02. Select the model
Press [E] on the keyboard, or Edge mode-Select (press [E]) inside Road Kill and drag-select the model to make it live. The Road Kill interface is just like Maya, so [Alt]+left-mouse button will rotate, [Alt]+middle mouse button is pan and [Alt]+right mouse button is Zoom.
03. Place the seams and cut
Once you decide where you want to place the seams just [Shift]-select the edges one by one or double-click the edges. Now just press [C] or Edge mode-Cut select for cutting edges. In case you want to stitch it back together, select the edge and press [W] or have Edge mode-Weld selected.
04. Export UV Map for texturing
You have now finished the UV map, so exit the file (you don't even have to save it). It will now update back in Maya with its new UV. You can then create a snapshot of this map to paint your texture map. Select Polygons>UV Snapshot and now go and have some fun painting a texture for your 3D model.
Expert tip: Pick you seams
Try to keep UV seams to a minimum and carefully choose where to place them so they are least visible to the viewer.
Words: Rohit Jagadisha
Indian-born Rohit lives in Dubai and is working as a 3D generalist at Real Image Productions, heading the modelling and texturing department.
This article first appeared in issue 187 of 3D World magazine.
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