Terragen 4 is not fundamentally different than TG 2 and 3, so older resources may still apply. The general workflow, if you need terrain, would be to use either a Heightfield export to export a heightfield, or a Micro Exporter to export geometry, then create your camera and export as FBX, which TG 3/4 can import. If you only need the terrain to lay out the camera path, then the Heightfield approach may be easiest.
If your terrain does not already consist of a heightfield (e.g. you use Power Fractals and Displacement), you can use a Heightfield Generate, feed your terrain shader network into the Shader input on the right, set the heightfield size, position, and resolution parameters to correspond to your needs, then click Generate. Finally, right-click the Heightfield Generate node in the shader network and choose Save As. You can save as TER (a Terragen-specific terrain format that is also supported by many other applications), or EXR. 3DS Max can probably load EXR and use it as displacement. Just keep in mind that everything scale-based in Terragen is measured in Meters, so you'll need to keep that in mind when laying things out in 3DS Max. You want to match your 3DS Max displaced terrain size to the TG size, if possible (this size is specified in the Heightfield nodes in the above workflow).
I hope that gives you a start. Let us know if you have more questions.
- Oshyan
