Here, we can see a number of features of the shower stall that has been floated with mortar. That thing next to the navigation diagram is where the main temperature controller will go - a major piece of the shower plumbing. Down below, we see some white square thing, the shower stall step, and the drain.
The lines on all this mortar are very crisp - both the inside and outside corners. How this is achieved, along with the nice flat smooth mortar surface escapes me. Once all this is tiled over, you'll never know there's all this ugly and smelly stuff underneath that protects the baseboards and other underlying construction materials from being subject to rot.