I’m playing around with blender and modifying .niff (mesh) / .dds (texture) files, there is an import/export plugin that brings in these file types.
When i import a mesh I notice their isn’t a mirror modifier applied to the mesh or material. The only modifier is some Niff data. If I go into the UV/Image Editor, some of the texture maps are made up of only half of the mesh and mirroring the the texture on both sides of the mesh. Does anyone know how this is done? Here is an image of the UV Map layout
If I select a face on either the right or left side of the mesh, the same UV map island faces are selected.
So blender is applying a UV mirror with out using a mirror modifier. I haven’t seen any tutorials or examples on how to do this. Any suggestions on how this is being applied and steps involved of duplicating this? Thanks.
My guess is that there is no mirroring involved. Simply overlapping UV islands. If you were to select one half and move it using G in UV editor you’d then see the island for the other half that it was stacked directly on top of.
Exactly what @JohnMalcolm1970 said. This is done to maximize texel density, i.e. to provide more texture resolution. Sometimes it’s feasible like in your example. Sometimes it isn’t - for example, if there’s writing on the texture, it’ll be mirrored on one side.
If you want to do the same for your own models in Blender, it’s quite simple - the Mirror modifier by default does exactly that (so long as you don’t enable any UV flipping options). So you model and unwrap only one half of the model, and the modifier flips and overlaps the other half for you.
This doesn’t go just for symmetry. For example, say you model an object that has lots of nuts and bolts on it. It’d be quite a waste to place each and every UV island for every nut and bolt individually, so it’s common practice to overlap all of them, thus making them all use the same exact part of texture. This of course makes them all look exactly the same, but such are trade-offs when you’re dealing with efficient utilization of textures.
