This was originally a vertical panorama, shot in infrared, with the color shifted towards sepia. It was then cropped, duplicated and flipped to produce a mirror image, then pasted back together to produce the final image.

Notice that the angle goes high enough to actually capture the trees behind me. You can see this towards the top of the picture. The camera that I was using at the time had an LCD viewfinder that could be tilted up at 90 degrees to the lens, so you ended up looking down rather than straight ahead. This enabled me to produce a 180 degree vertical panorama where the top of the picture was whatever was behind me.

Imagine the panorama printed on a long piece of paper with one end in front of you, proceeding up and over your head, with the other end of the paper behind you, the whole thing forming an inverted "U" shape. To view it properly, you would stand inside this overhead arc and you could tilt your head back to see the image above you, or turn around to see what was behind you.