Once, I googled for a photo of a view outside a train window in Japan. This was before I moved here, so I couldn't just take my own photo.
Upon getting permission from the owner of the image, I drew a running mecha on top of it as an experiment in trying to match the color, lighting, and image quality with the background, so it would seem like the mecha was actually there.
It turned out semi-ok, but I'd like to try this sometime later again.
The lighting, shading, and colors look great with the image!!
It still looks kind of unnatural, but this was the best I could do at the time.
I have my own digital camera now so I can find a good angle for myself if I want to do something like this again
Something that really adds to it, is the glare on the window that passes over the mech, and the blurriness making it look in motion.