DIY Laser levelling using webcam and laser level

[devmonkey]

It's cheap Sj4000 clone distortion is massive, if there is correction it does very bad job. I have cheap webcam and 0.08mm steel wire on order. Will try both laser and wire to rule out sensor nonlinearity errors.

One other thing that occurred to me, how did you ensure you moved the sensor/vice assembly absolutely in a straight line? Any deviation in this procedure would show up as non-linear errors in your linearity measure since it would have been impossible to get the laser perfectly planar with the granite. This applies to both types of laser dot and line. I think you need a precision straight edge as well as the reference surface to check the accuracy of the system.