CCG/Modelling: Textures and File Sizes
TEXTURES and FILE SIZES
Textures images should be .tga files (24 bit).
An alpha channel may be used for opacity, within the .tga file (32 bit). Alternatively, a separate .bmp file (16 or bit) may be used for opacity. Note: In TS2009 onwards, there is no performance penalty for having separate primary and alpha images. The textures are built when commiting the asset into the game from Content Manager.
While .jpg files may be used, it is not recommended, as they are a compressed file format, and lose quality if repeatedly loaded and re-saved. The .jpg file format does not support an alpha channel. In TS2009 onwards, there is no performance hit for using .jpg images as, again, they are converted to textures by Content Manager on committing into the asset database. Image quality is the sole reason for avoiding them.
The materials are of Multi/Sub-Object type (one M/SO only per model) and we have used UVW Map and Unwrap UVW for texture allocation. Textures must be of following pixel dimensions: 8, 16, 32, 64, 128, 256, 512 and 1024 pixels. Maximum aspect ratio = 1:8 e.g. 64x512
Diffuse Maps: In many cases a single 512x1024 24-bit .tga file is sufficient to texture a locomotive. TS2009 onwards now supports 2048x2048 pixel textures, though only one of this size per asset should be used if possible. We recommend not making them any larger than this.
Occasionally an extra texture (say 128x256) can be added.
Reflection maps are supported (24 bit colour .tga). We generally set train body reflection amounts (in 3DSMax) to 10 and windows to 25. Do not use .bmp formats that are uncommon.. such as 16 bit colour, 256 colour,or 16 colour. (some imaging pograms do not save compatible formats for these)
For TS2009 onwards, DO NOT use reflection mapping on rollingstock bodies. The shine is now controlled by specular mapping using an alpha channel in the normal map. Confine the use of reflection maps for wheel rims or chrome finished parts, and take care with the settings as undesirable effects can be caused in night renders.
Opacity Maps (greyscale .tga) are also supported to the EXACT same pixel dimensions as the diffuse map.
TS2009 onwards handle blended alpha differently from previous versions. Use masked alphas where-ever possible, and try to confine blended alphas to areas where they will not be stacked..(one viewed through another)
Where possible, opacity maps should be included as an alpha channel of the main diffuse texture .tga file.
Reflection and Opacity maps must not be used together within the same texture. Reflection and Opacity maps must not be used on digits. Window opacity is derived from the material and opacity settings - See Material Types for material naming conventions.