There is no automated function to create a render effect of this type. Using Function Nodes, which are mathematical building blocks, you could probably create a solution, but unless you are mathematically inclined and willing to experiment it's probably not worth the time. It would also only be lines, with no altitude readings.
The bottom line is TG2 is not primarily intended as a GIS application, so it does not have many of those types of features. However you can export terrain from TG2 that other applications like GlobalMapper can read, and you could then create topo lines on another program.
- Oshyan