Photo backdrops add a feeling of distant scenery between the actual 3-D modeled scene and the cloudy sky. The area previously finished required very little (about a foot) of backdrop, while the area I'm currently working on requires more. Generally, I use them where the track, a road, or some other element runs pretty close to the wall, and the planting of lots of trees to soften the transition from 3-D to flat vertical is impractical, because the area is narrow.
The backdrops I use are from
Backdrop Warehouse. They make a great product, but the website is a little hard to navigate! But once you find what you want and order it, you get a first class product and great customer service. These aren't just printed paper, they are heavy material, kind of like good quality wallpaper, and are actual printed photos of distant scenery. The scenes have a soft, slightly fuzzy look to them, as they should, to give the impression of distance. They come with clouds and sky, which I trim away. I prefer the backdrop scenes to be uncluttered and not full of detail like buildings.
Above, I use a compass to mark where to trim the bottom to conform to the terrain, then tape the scene to the painted background, and mark the top and side edges with a pencil. Then I apply contact cement to both the back of the scene and the wall, let it tack up (about 15 minutes), then carefully place it, just covering the pencil marks on the wall. I use a small paint roller to make sure it's firmly pressed together. Trees and other vegetation will conceal the edges and bottom.
It's easier, of course, to apply the backdrop before the terrain contours, but it's sometimes hard to visualize where they will be needed, before the terrain is built up. Above is an area that will have a very low, fairly flat contour, and track close to the wall, so I went ahead with the backdrop here in advance of the terrain.
