Welcome back today we are going to be going over an important set of 3D modeling. UV Mapping. Not going to lie, UV mapping can be difficult and tedious, but it is very important for 3D modeling. At its basic it is the internal information that allows textures to be translated onto the surface of a model's surface. I like to imagine every bit of the 3D surface area to be flattened into a 2D space. Another good example is something like a cutout paper cube. It becomes more complex with more geometry and decisions always have to be made for where seams are going to be shown or whether they be hidden.
Every person comes up with their own way of doing this and practice makes you better. Keeping in mind the limitations or requirements of the rendering system, may be able to get away with more or less. First thing that I ask myself is whether or not I have to stick with one material. Second is whether I can use tiling textures. These two things can be determined from the renderer’s information and what the model is. Let’s act as if both are available for now.
So both tiling and multiple materials are available to be used. This makes things easy and fun. Find or make some tiling textures that your model needs and apply them to their own materials. Once that is done you can separate the surface mesh into the same groups and apply the appropriate materials to them. First step is now done. Next is to actually start the UV mapping. Up until this point we just set up the materials to show on the model's surface.
UV mapping is starting by marking the seams or edges where the 3d surface will be separated, cut, to allow it to flatten into a 2D plane. Carefully choosing where these seams will be is important. For example if it’s a cube, let’s say some dice, you can mark these seam the same as the paper cube would be cutout as. If it’s something more organic like a doorknob it will be harder to choose where they will be. Having too many will make the seams very obvious, but having too little will distort the image on the surface. For something like this I prefer to think of it like a cylinder, the front and back facing surfaces will have a cut all around it and then a cut going down the underside. Translate this to the more complex shape of a doorknob hiding the front facing seam behind the back of the spherical knob or under the locking mechanism. The cut underneath is unavoidable but that is why it underneath; it is less likely to actually be seen.
Next, after all the seams are marked, we can finally unwrap it. Different editors have this placed in different areas. In Blender3D it is located at the top of the right click menu, context menu, in object model while the mesh surface is selected. If this is your first time, or if the prior steps were not done, it will look like nothing happened. Be calm, it is displayed in a different area, the UV Editor. Switch to it and we’ll see that our hard work is now revealed. Some tweaks in the UV editor may be necessary for it to look correct, but very simple objects are often done at this point.
I have now gone over UV mapping, albeit a very quick overview. Trust me it takes a lot of time and practice in order to get UV maps working on most models. Hopefully this quick overview has shed some light on it and as always if you are having trouble feel free to message me on discord or even by email.