With this image scaled way up and me standing near the bottom of it, it felt like I was looking up at a real skyscraper. 

They tell you how big the original image is and what the current size of it is, as well as how high off the ground it is. 

Some images are shown on the ceiling because I guess they took the picture looking up so why shouldn't you look up to see it? You can adjust the height of the picture/ceiling too. 

I guess the "person for scale" thing works well here, since you can see I moved way off from this and yet the picture is still freekin huge. 

I'm really not sure why the humanoid figure is there, but I guess it's supposed to give you a scale of how big the picture is. If I stood next to it, the humanoid figure is actually about 2-3 inches taller than me (putting it around 6 foot tall)