I was once the CTO for a small educational startup/company that was trying to make small (10ish people) portable planetariums. The goal was to install them in schools or other children/family friendly areas and serve the edu-tainment market.<p>It's actually quite interesting how many design and technical problems we had to solve to make the planetarium a "breathtaking" experience. Some interesting ones.<p>* Projection optics for a curved surface are a whole other ball game to a flat cinema screen. Pixel sizes change radically across the surface, and you have to use a combination of optics, clever encoding and film making to keep the perceived quality uniform across the entire surface.<p>* The gold standard for planetariums is that when each person looks at the "center" of the screen, no part of their visual field extends past the edge of the screen. That ensures the complete immersive experience. I ended up diving into biology and medicine literature to understand the size of the human visual field across age. At the same time, spent far too much time playing with the geometry of the planetarium.<p>* Air change. I found out that commercial spaces (concert halls or airplanes etc) change the entire air several times an hour. I then went about trying to min-max the number of air changes while keeping the exhaust fan noise levels imperceptible in this very small planetarium.<p>And many more. I also found interesting ideas. One publication claimed that if you played a loud sound, along with some sudden air flow changes just before starting your show, the audience would relax more. I wasn't able to implement or experimentally test this.<p>Special shoutout to the European Space Agency, who released many high quality full length planetarium shows under open licenses.