Continuing to explore how to deal with some background images on the Central End, I've discovered some neat images using the Streetview feature of Google Earth ... this going beyond the higher level 3D views that I explored earlier.
These two views are taken along a freeway transition ramp between the Northbound 5 and the Eastbound 84 in Portland, Oregon. If nothing else, I could use elements of such images to construct the background, possibly adding some dimension using building facades applied over the image.