Hi everyone!
How can I add overscan to a render in Terragen? I've noticed that when I increase the format, it just makes the image larger rather than expanding the boundaries.
What I've done in the past is to increase the image width and height by whatever percentage of overscan I want, then modify the camera Focal Length in mm parameter by that percentage as well.
For example, if my original render resolution was 1000 x 600 with a 40 mm lens, to add 20% overscan I would increase the render resolution to 1200 x 720 and decrease the focal length to 32 mm.
You can decrease the focal length as Kevin said, or leave the focal length as it is and increase the "Film aperture in mm" values. For example, to add 20% overscan you can either divide your focal length by 1.2 or multiply the film aperture values by 1.2.