Experiments with projectors and video calls

08.16, Thursday 4 Jun 2020

I’ve been posting recently about video calls and online talks. And, in the spirit of that, last week tweeted about a ridiculous experiment with an overhead projector.

Here’s what I did, with photos.

The setup is this:

  • I take the call (or presenting the talk) on my laptop
  • A few feet away, behind the laptop, is my overhead projector. It faces me (it’s bright!) so the projection appears on the wall behind me, effectively the background for my call
  • The projector is plugged into an Apple TV, which is screen mirroring from my iPad
  • I carry my iPad and drawing on the screen. Whatever I draw appears, projected, on the wall behind me. (I just scribble in a random drawing app using a black background.)

Seriously, check out the photos at that write-up. It’s a bit stupid. Plus the rest of this post is about those photos, so it’ll only make sense if you follow that link.

So, did it work?

It’s fun! And funny!

It’s funny to draw a lightbulb above my head which is visible to everyone else, even if I’m not full screen and speaking. Design for thumbnail view!

It’s funny to look sideways and pretend like laser beams are coming out of my eyes.

It’s funny to draw a speech bubble for myself.

Or to doodle illustrations around my head. Or an ocean scene, giving myself a diving helmet. Or to scribble a diagram.

What didn’t I expect?

The reason to experiment like this is classic design thinking through making:

  1. It’s hard to imagine the consequences of something that is itself only in your imagination. By making it, you give yourself a solid foundation, and consequences and possibilities suddenly pop into view.
  2. The material forces you to do things you didn’t plan on, and every workaround and quirk reveals more opportunities.

In this case I’m trying to learn about the interaction design. So what thinking through making says is that I should prototyping the interaction, in however janky a fashion. (Another approach is iterative development, always doing only the most straightforward next step that gets you closer to your goal, but always learning and re-evaluating what that goal is. I like this approach too.)


What I didn’t expect…

  • how interesting it would feel to draw on the wall instead of on an overlay on my screen. Once it’s on the wall, I - as a presenter - can move around, pointing and interacting. It’s not a green screen weather forecast, I can see the wall too!
  • wanting to gesture to trigger a drawing. I wanted to be able look sideways and open my mouth to create a speech bubble. Or hold a finger up to project a big number behind me, enumerating points in my argument. I was surprised about how live the drawing feels, and I want to capture and extend that.

What next?

The projector is janky and lo-fi, which makes it fun, but it would be neat to do this in software instead.

(The particular problem with the projector is lighting, as you’ll see from the experiment photos. The projection needs a dim room, the presenter needs a bright room; it’s an unhappy compromise.)

There’s a technology called virtual webcams – meaning that Zoom, instead of using your built-in webcam, uses a “camera” which has been manipulated by some other software first.

Here’s how to set up a virtual webcam using OBS. OBS?

OBS = Open Broadcaster Software. It’s free software that, with a bit of work, lets you do things like green screen.

Case in point: I caught on Twitter today that Mark Pesce is doing green screen Zoom talks – check it out, it looks fantastic.


what I want is…

  • to make it look at though I’m drawing on wall behind me. I don’t want it to look like I’m floating in space. I want the drawings to attach to my actual room and not to the screen – so maybe I could stick motion tracking markers on the wall behind me, and dynamically cut out and replace a fixed piece of the background to use as the virtual drawing pad?
  • to draw on my iPad and have it appear on that virtual wall. Now this… I have zero idea how to achieve. Any thoughts?

I’ll give it a go when I get a chance. Who know what I’ll learn. Thinking through making, I COMMEND THIS AS A PRACTICE.

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