I am glad you noir folks finally solved the projection box mystery at 6637 Hollywood. Kudos, I knew you would do it!
I was a set and props man from 1988-2004, and worked in a
whole lot of the places that you post and have lurked in silence here for the past many years. After installing Proton Sony Monitors in the 80's, and installing RP ( rear projection) & FP screens and working with Iwerks projection units I bet it had to be a projection device. A tilted inner screen, and, as with any one of a kind prototype installation... they had to add that extra overhead sun shield (I can see that it bows) after the construction to get the right effect.
Projecting moving or still pictures on a screen during daylight is a real tricky thing, but I was surprised that someone tried this out so early. I would bet it was not very successful during the day, and it probably did good at night. A RP screen has to have a slight matte viewing side to reduce glare, and a semi diffused rear side to reduce light "bounce back scatter" so back then I think they would have had to use glass , but they could have used stretched fabric, and deal with the wind/ repair issue later. The lack of a visible exhaust vent for the carbon arc, or super bright light source is a little puzzling though.
I spent 2004-2020 as a Construction & Design manager for one of the Hollywood restaurant groups so I can tell you the Geisha House was designed in 2004 and lasted until about 2014, and that it is not the old Virginia structure.
Additionally, the Las Palmas and Hollywood Bldg. with rooftop "widows walk" building was a 2 year office of Dodd Mitchell Design ( Hospitality) about 2008. I was there 5 or 6 times. The Atrium was not part of the offices , but private and accessed through the icky restaurant or the Las Palmas entrance. That restaurant was a greasy spoon. The Hollywood BLVD. entrance to DMD had the old ancient door, and all of the old hexagonal tiles and stairs.
Lastly, 6637 is slated to be demolished soon, it looks like its going to be a hotel. See LA Curbed , item 18.
https://la.curbed.com/maps/hollywood...s-construction
Sorry to be long winded. I hope I posted it correctly.
You folks are a great forum and resource for those of us who live and work here and all of the history that goes along with it!
JE