Terragen 2 is primarily a renderer. It is not explicitly intended as a terrain modeler for other applications. In other words while it has great tools for creating realistic terrain, the focus is on rendering those terrains within TG2, not exporting them to other systems like games, or other renderers. Data interchange will be more of a focus in the future, but even then we will be aiming more at other high end 3D applications like Maya, Softimage, etc. rather than game purposes. The effects industry is just a larger, more immediately applicable market.
That being said, if all you need is normal heightfield output (grayscale), right-click on a heightfield node and choose Save As. Give it a .ter extension. Then use
TerraConv to convert 16 bit TIFF. You should then be able to convert this to any format you need.
- Oshyan