This Terrain Data File is a text based definition of how different surfaces should react, whether they be driven or collidable. It also contains special effect definitions such as dust.
This file is referenced via each layouts GDB file, and there is usually one common file per group of track layouts.
If there is no terrain data file specified in the GDB file, then the default Terrain.tdf in the Locations folder is used.
The file can be opened and modified in any text editor.
The [TRACKVARS] section allows the setting up of variables which can be used through out the file in multiple feedback sections in place of hard coded values.
The TDF file contains multiple [FEEDBACK] sections. These define the properties of driveable and collidable surfaces. Each surface has a number of properties and variables, which effect the physical reactions, visual impact and sounds triggered. Finally there is a material section which defines the prefix required on an object material for this set of definitions to be invoked.
The [LOOSE] section defines the "Reaction" special effects which can be triggered in different Feedbacks. For example sparks, smoke, skid marks can all be defined here and then referenced in the appropriate Reaction entries.