The T Class cabin is a quite unique compared to typical cabins made for Trainz. It utilizes the tag "outside-visible-from-cabin", which allows the exterior locomotive model and effects to be shown from the cabin. Without careful modelling and planning, this task can be difficult to accomplish.
To begin the exterior locomotive shell needed to be obtained to start the modelling process. Some elements from the exterior are low poly and need to be hidden from the high poly cabin view, which is done through a script. Modelling the cabin is a processing of scrolling through endless reference photos to replicate each detail found in the actual T Class cabin. For this cabin, a high-poly model of over 1 million triangles is created to serve as a reference for the low-polygon model. This process is known as a high to low bake. The high-poly model will have beveled edges, nuts, screws, and other detail that would be otherwise too costly on performance.
Once the high-poly version is finished, a low-poly version is created that will actually be used in-game. Typically, this is a fast process if the modifiers are stripped from the high-poly version. In this comparison below, you can see the high-poly and low-poly versions of the front-panel:
When the model of the cabin has been complete, it needs to be UV unwrapped to have the proper areas where the coloured texture will reside. To make sure the detail will be high resolution enough, a colourful grid texture is used to check along the way. When the resolution of the UV map is at the desired amount of detail, it's off to Substance Painter for texturing.
During the texturing process, lots of metal wear is shown on most parts of the cabin, (just like the prototype). We also make use of height maps throughout the cab, which creates an illusion of 3D geometry without it actually being there. For example, the screws (of which there are many) utilize this technique, saving thousands of polygons, thereby improving performance.
There's still more work to be done with the dials, scripting and final tweaks, but this cab is already drool-worthy. :)
