DIY Laser levelling using webcam and laser level

[devmonkey]

Some notes on HD cameras for people wanting to move beyond VGA.

Why bother? In order to get more vertical range, VGA gets you ~2mm which is not very much when starting with a very unlevel surface, and it is quite hard to align the laser to within 2mm of the thing you are trying to level, but not impossible by any means.

Webcams usually produce two types of video stream, a compressed stream (usually MJPEG unless you have a 2-4k camera in which case it will be h264) and an uncompressed YUV stream. This app can only use the uncompressed stream, both because of how it interfaces to the camera, but also because compression introduces a load of artifacts into the image which will lead to alignment errors.

The problem, most webcams use the USB2.0 standard to connect to your PC. USB2.0 can ship VGA(640x480) uncompressed at 30 fps, moving to FHD(1920x1080) this drops to 5 fps. This means it takes 6 times longer to take a reading, I don't know if this matters much other than slowing the whole process down.

To get 1920x1080 at 30 fps you need a USB3.0 camera (and a PC with USB3.0 ports), these cameras are harder to come by and are more expensive. If you are looking for one then try and check what formats and rates it actually produces before you buy it.

Hope this helps.