There is a feature in Terragen that allows you to render curved terrains and it gives options of sizes like Earth, Mars and the Moon. I've rendered with this feature checked but it still comes out like it normally would. Can anyone help?
I don't think the curves on any of these surfaces would be noticable to the naked eye, the area you can render in TG is too small for them to have any effect I think. Not sure what the point of the feature would be actually, but maybe you can find something on the TG home page?
You can't make a planet in TG if that's what you're asking (at least not without a great deal of editing in PS or something). I do recall someone once made some images that looked a bit like planets but this involved a round island viewed directly from above (ie the water was like space around the planet...) I think the easiest way to get a curved -horizon- is to mess around with the camera focus.