UV Mapping

UV Mapping is the process of taking a 3D object and creating a 2D representation of it, so that it can be painted on with precise detail. It is the laying out of an objects polygons so that an even texture is present, making sure  no distortion occurs when painting is required. Distortion can be seen if you apply a chequered texture to the model, and the aim is to lay out the UVs so these checkers become perfectly even. It can most easily be described using the 'open box' analogy, where UV Mapping is essentially like 'unfolding' the object until it is flattened out:

As you can see, each part of the box can be easily identified and visualised as if it were going to be put back together. 

When UV Mapping more complex shapes like those featured in my door, different methods of projecting the different faces of the objects are required:

Planar Mapping: Projecting all faces of selected object that are visible to selected projection axis.

In other words, if you choose to project using the Z-Axis, only faces facing along that direction will be mapped onto the UV Texture Editor. In this case that is the front or back of the box. If it were the X-Axis, it would be the left or right sides, and the Y-Axis would represent the top and bottom. This is the most widely used form of mapping, as it covers most basic shapes easily.

Cylindrical Mapping: Creates a cylindrical projected around the selected faces.

This kind of mapping is perfect for shapes primarily made of cylinders (obviously) when the rounded parts need to be mapped. Though it might sound as easy as clicking a button and it's done, it's not. I ran into a problem with this method, but managed to fix it swiftly and easily:

As shown above, the projection has laid the UVs out in a very non-workable way (circled in red). The solution to this was even more simple than I could have imagined...

On the object itself, you can click one of the boxes situated on the manipulator to bring up more options for you manoeuvring tools. One of these is a red handle (circled in green), which controls the orientation of the UVs for the selected object. If you click that, you can free move and rotate the UVs. In this case, we need to rotate the UVs until they are in a perfectly straight line (in line with the darker purple). When it's straightened up, cylindrical mapping is complete!

The idea now is to carry on unfolding the rest of my model using these projection methods.

Here, you can see the unfolding UVs of the right plinths base, stick and ball. The base UVs were created using planar mapping on all each axis, then sewing the UV edges together to create the 'unfolded box' effect. The stick was accomplished using the technique outlined above and, since the ball is an unaltered polygonal shape, had a perfect set of UVs already applied to it.

Here we have the UVs for the whole object unfolded and ready to be packed. UVs must be packed into a positive space (essentially the top-right section of the editor graph) for them to be applied to the 3D model correctly.

Here, the UVs were all packed into the right space, though they weren't making use of the entire space available. The bigger UVs are within the grid, the more pixels are allocated to them, therefore the more detail can be applied to them. I wanted the main biscuit and Happy Faces to be the most detailed parts, so I made them bigger than the rest.

Here are my final set of UVs, making the most of the space as I see fit. The UVs of the plinth base are red (overlapping) because I'll have a left and right plinth which will be using the same set of UVs for its texturing/colouring.

I actually found UV Mapping an absolute nightmare at first, but as soon as I'd started to understand it, the process seemed to fly by. I actually had a lot of fun with this part of the project! Now I can begin with the colouring and texturing!