Mirror Turns Webcam Into Document Camera

This is one of those so-simple-I-wish-I-invented-it hacks. Professor [Michael Peshkin] is teaching his engineering students remotely. While he has a nice second camera that he can use to transmit whatever he doodles on paper, most of his students just have the single webcam built into their laptops.

The solution is to put a mirror in front of the laptop cam, and flip the image left-to-right in software. They use Zoom, which has a mirror mode. Done.

The trick is making a nice frame. [Michael] has bent one out of wire, but suggests that a mirror compact works about as well in a pinch. It’s super important that his students can ask him questions backed up by drawings, and this reduces the startup cost to nearly nothing, making it universally useful.

[Prof. Peshkin] is not a stranger to mirror-based pedagogical hacks. Seven years ago, he showed us how to make a transparent whiteboard for video lectures, and it blew up on Hackaday. Since then, there are hundreds or thousands of Lightboards in the wild. We hope this idea catches on as well!

12 thoughts on “Mirror Turns Webcam Into Document Camera

  1. Saw the same approach on reddit the other day. The poster was taped a pencil vertically to the back of the laptop, then put a CD shiny-side down on the pencil. It leaned over the lid on a 45 degree angle, and mirrored the notepad.

  2. There was a massive labor day twitter thread, started by John Umekubo, about similar designs, in which I participated. It resulted in his summary blog post:
    https://johnumekubo.com/2020/09/07/the-pocket-document-camera/

    I came up with one of the designs, a parametric design in a range of sizes, created in OpenSCAD:
    https://gitlab.com/mcdanlj/docucam
    https://www.youmagine.com/designs/docucam-laptop-document-camera
    https://www.thingiverse.com/thing:4590755

    There are several others. But I’m partial to mine! ☺

  3. The stupidest thing about this is that they no longer have the “reverse” function in webcams anymore… too many people were disturbed by their camera monitor doing the “opposite” of what they do and demanded their cameras to be automatically in “Mirror mode” so it would look the same as “acting” in front of a mirror… but that entirely defeats the ability to read anything that is held up to the camera… They should restore that functionality and make it available with a simple mouse click button on the display.

    I guess everybody got what they were b@#*ing about and now are finding out the problems inherent in their demands. LOL

    1. Most PC laptops do. Most Chromebooks do. There was a shortage of doc cams at a local public school district, 6months ago. I just shrugged and suggested using the front facing camera, a dollar store compact mirror and, some green floral wire. I was more or less called an insensitive clod by a couple teachers. I didn’t realize they had 750k in the pipeline for COVID relief. So they got iPads and a Swivil for each teacher, and an iPad document stand. That’s under 2k per teacher. So they can still use their PC without a little dollar store hack hanging off. Take it for what you will.

  4. With my setup at work, I have a second camera that I can plug in USB any time to provide a secondary source. Also, I am fortunate in that my laptop has software for all sorts of camera tweaks, so mirroring/flipping is very simple. I don’t have this on my personal laptop and I agree that it is a nuisance.

  5. OBS has different plugins for Linux and Windows that are able to mirror the video and present a software webcam; my wife is using this for math instruction.

    There is proprietary software available as a free download, ManyCam, that does this intrinsically.

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