TG-Max is a MaxScript for 3DS Max which allows camera and lighting data to be transferred between 3D Studio Max and Terragen. The program is broken into two versions; Lite and Pro. Lite is free(for non-commercial use only) and includes simple features to export camera data from 3DS Max (limited to 100 frames) - import terrain geometry - as well as controls for animating camera zoom and banking. Pro version ($30 for commercial use) includes features to control and animate sun - longitude - latitude - time of day controls - panorama script creation - water preview - and network rendering.
To Install either drag-drop MSE file into 3DS Max or copy file to 3DS Max folder scripts/startup . Open Utility panel - MaxScript - and click on TG-Max.