2020 has been its own horror film by any measure and the cancellation of trick-o-treating in some places was of little consequence at our house because my kids were not having it.

“We’re not going out there people are crazy Dad,” said one of the twins.

“It’s not worth the candy,” said the other.

No I don’t know which one said which line, don’t try to change the subject. COVID’s ongoing rage and a good portion of people around us whom dismiss the basic mask wearing safety protocols have broken my kids. Candy is a kid currency, more valuable than actual money and significantly more tasty, and even they know it’s not worth the it.

It was time to look for silver linings. Enter Halloween decorations.

I admit that I like decorations. I don’t care about the theme as long as it’s fun. The kids are into dragons, so we have many a inflatable Halloween dragon. We have smoke machines because Monica loves a good low fog. Giant spiders and spider webs hanging from the second floor? You bet. This year though we needed something more. Enter projection windows.

Projection windows are not a new thing. You can buy kits online that loop, you can make them out of screens and sheets, it’s been done. But we hadn’t done it and it just so happened I had just the things to do this for basically no money, so let’s pull some stuff together shall we?

Surplus office gear assemble

Ignoring the fact that I have stacks of technology from years of junk collecting (you build things, you have parts boxes, it’s a given), I also happened upon a lot of higher quality gear from liquidation (a long story told another time). In this grab bag was just what the spooky ghosts demanded.

1. A couple of Viewsonic projectors (both of which had HDMI)
2. An one input, four output HDMI signal splitter
3. Rolls of vinyl transfer tape of various widths
4. A pair of giant speakers with built-in pre-amp
5. Lots and lots of very long cables
6. A Chromecast. Well, lot’s of Chromecasts, but I only need the one.

These six or so items are just enough tech to make dancing skeletons and other random things you find on YouTube ready for action.

Turning a window into a ground glass

As I alluded to above in some setups people use a thin white sheet or curtain, similar to a reverse projector screen setup. I choose a different method.

Vinyl transfer tape is not something most folks keep in the house or in their shop. It’s one of those specific purpose sort of tapes that I don’t use often, and definitely not in the large size of this particular roll.

Two of the tapes more interesting qualities is that it doesn’t leave a residue and has a ground glass texture appearance. As you can see in this daylight photo of one of the windows with it applied, it gives a soft affect light effect just like an unfocused ground glass on one of my large format cameras.

Since we don’t want to bring the outside into focus, let’s instead focus our projectors at the two windows instead.

Projects and splitting oh my

With three windows upstairs (symmetrical no less), the goal was to use the two outside windows as projector screens and the center window for the speakers. To accomplish this and keep things in sync, I opted for the Chromecast and HDMI splitter route to handle this, using the audio output from one of the projectors to the pre-amp’ed speakers.

This isn’t the prettiest wire setup, but that’s hard to do in two kids room’s with with 40 foot cables running every direction. Beyond that however, there isn’t any fancy tech here; we’re just pumping signal.

The effect in action

Pictures really don’t do it justice, so here’s a short clip of it in action.

Happy Halloween! If you find yourself out on this spooky evening, stay safe out there.