As I’m carrying on with the creation of 3D models, it is time to also prepare for texturing/creating materials. I have started my research with the most essential element that every 3D modeller should be aware of – UV mapping. Creative Bloq prepared a great introductory article about it and I will make a breakdown of what I’ve learned from it. Many fragments of this post are copied segments of the original article:
UV map – flattened topology of the model and basis for map bakes
UV space – based on a 0 to 1 grid, with 0.5 as the middle coordinates, a UV map consists of your 3D model’s XYZ coordinates flattened into 2D UVW space – or tile, as it’s called.
Depending on your modeller and mapper, 3D’s horizontal X-axis equals U in 2D space, vertical Y equals V, and the depth coordinate Z equals W. There is no madness to the letters, only method: 2D’s UVW is used solely to avoid confusion with 3D’s X, Y and Z (3D translated to flattened 2D).
Available in some renderers: UDIM – U-Dimension. In simple terms, UDIM makes UV mapping and texturing easier by enabling you to create multiple UV grids for the same model by allowing you to have 10 tiles on the U-axis, and an (almost) infinite amount on the V-axis.
UV mapping shouldn’t be distorted – scale and size are very important.
Normal map is often wrongly considered as a glorified bump map, which isn’t correct (it has more functions than height and depth maps).
The direction they face defines the direction of smoothing, and the side or direction your materials display on. For example, if you’re creating a scene inside a box, it would be natural to have the texture on the box’s inner walls face inward, not outward, so you can see it.
A smoothing group’s function is to make your model appear smoother without adding polys to the mesh. It’s a sort of pseudo-subdivision surface where if two or more polygons share an edge and are members of the same smoothing group, they will render as a smooth surface.
.fbx export results with with tangents and binormals checked, but it also helps to use multiple, non-flipped UV maps or sets, at the cost of load and the convenience of having everything in one map.
If you’re absolutely stumped as to where to begin unwrapping, look at your model, and, if you haven’t already, divide it into groups or material groups. Then go for the largest, or most complex items first. These areas are often the most visible and time-consuming parts of your UV map and texturing, and it’s here you’ll have the least leeway when it comes to time and errors.