2020-03-22 (discussion on hacker news)





With so many people and students around the world working from home, we really need some easy to deploy shared whiteboard solution. This is especially important for pre-college students who may not have access to high end hardware.

This Apollo 13 style camera stand (shown in left-handed version; flip for right-handed writers) should address the hardware problem satisfactorily, and make a smartphone with common video communicationa apps into a a poor man's overhead projector/document camera.

The preferred height is 20-25cm (8-10in), high enough to let the camera focus, low enough so you can look at the image in the display while you write and make sure the writing is in the displayed frame.

The software side is a bit lacking though: most apps lack manual controls for all the following features, which are really necessary for effective operation:

orientation. When flat, the phone cannot tell whether we want portrait or landscape. Workaround: start in landscape and slowly lay the phone flat on the support, hoping there is some hysteresis on the accelerometer's input;

When flat, the phone cannot tell whether we want portrait or landscape. Workaround: start in landscape and slowly lay the phone flat on the support, hoping there is some hysteresis on the accelerometer's input; focus and brightness. The writer's hand moving on the sheet will trigger automatic controls in the camera and destroy quality and bandwidth. A stable light source opposite of the writer's hand, and a sharp, not too thin pen, may give a bit of relief;

The writer's hand moving on the sheet will trigger automatic controls in the camera and destroy quality and bandwidth. A stable light source opposite of the writer's hand, and a sharp, not too thin pen, may give a bit of relief; frame rate, encoder quality. Especially low end phones do not have enough power to encode highly variable input (see previous bullet), resulting in unreadable images. An encoder setting for low frame rate (e.g. 1-2FPS) and high quality would be invaluable for such an use case.

All the above issues could be fixed with very little effort. I really hope video app developers will address this use case, which is especially important these days.