I am just curious. What kind of program would make panorama images? I want to shoot my city.
Since the perspective doesn't change, you could use any software that allows you to paste in multiple screenshots.
1. Take screenshots that cover the area you wish (i.e. go to the top left, take a screenshot, move right, take another - make sure there's a little overlap)
2. Import them all using the tool of your choice. You will be able to match them up, pixel for pixel...
3. When done, zoom out and crop the edges so it's nice and rectangular (or square)
It's a little work, but unlike with photographs, where things aren't pixel-perfect, this is.
Now I'm really confused - panorama images in Simutrans or reality? Anyway, Isaac covered the former, and for photos you'll need some dedicated program that can correct optical distortion (?) introduced by the lenses in camera.
I don't know if it would work with Simutrans screenshots but for real life photos, I usually use Hugin (http://hugin.sourceforge.net/). You just need to load the images, set the control points and choose the perspective. The program will do the rest.
@vilvoh: Should work. Can't imagine the software would choke on the fact that "you lined up your shots perfectly! Did you use a dolly or something?" :)