Hello again,

I’m still trying to achieve a decent projector calibration for our sandbox. I’m having problems with getting the yellow indicator to turn green. A secondary problem is that I don’t get the red crosshairs after the first set of tie points is collected. My guess is that the points are not good enough to do a calculation with, so solving the first problem may solve the second, but I don’t know.

Onto the first problem. I uploaded some videos of trying to take tie points. The first three are for the first three points and the last two are for a fourth point. Note: A piece of cardboard blocked up to half the depth of our box is currently standing in for sand, which is on order. This cardboard was also used to take the corner points for BoxLayout.txt. They are included at the bottom of the post in case they’re useful. The calibration video (https://www.youtube.com/watch?v=EW2PtRsQQr0&t=610s) says a perfectly level surface is not necessary so I don’t think the sand substitute is the problem(?).

Description of difficulties:
In the calibration video, the indicator seems to turn from yellow to green quite easily and remain green over a reasonable height range. Dr. Reylo is able to keep the target parallel with the sand surface and keep it green while taking tie points at various heights. The only adjustment needed was to decrease the sea level for the below plane tie point.

In contrast, I am generally having to raise the target quite high, tilt it, or both, to find a point where it turns green. When it does turn green it isn’t stable within a range or even a point. Some of the footage I link shows the target stationary while the indicator is flickering between colors.

This definitely doesn’t seem right, and the calibrations I’ve attempted took over an hour each to get the minimum twelve points, the vast majority of which time was spent moving the target around futilely.

Tie point 1: https://photos.app.goo.gl/x5bQf52YbgbeV1bR6 (target must be tilted)

Tie point 2: https://photos.app.goo.gl/V8aLHLGbWxMNNAhE8 (target flickers)

Tie point 3: https://photos.app.goo.gl/RxmroQR3Wqza8bBn8 (target is over a foot above the rim of the sandbox)

Tie point 4: https://photos.app.goo.gl/r2RfFDinMfV4QqjT9 (target does not achieve green)

Tie point 4 (2): https://photos.app.goo.gl/ompWFupoXWttZyyy7 (target won’t stay green unless raised high and tilted)

Command window outputs for the tie points in the videos:
cdm@admin-Sandbox ~ $ /home/cdm/src/SARndbox-2.3/bin/CalibrateProjector -s 1024 768
CalibrateProjector: Capturing 120 background frames…VRWindow::VRWindow: Vertical retrace synchronization requested but not supported
done
CalibrateProjector: Capturing 120 background frames… done
CalibrateProjector: Capturing 60 tie point frames… done
Tie point: 204.5, 192.5; -17.239, -21.0238, -98.2385
CalibrateProjector: Capturing 60 tie point frames… done
Tie point: 409.5, 192.5; -9.21404, -13.2975, -84.4043
CalibrateProjector: Capturing 60 tie point frames… done
Tie point: 614.5, 192.5; 12.0585, -7.30491, -81.1033
CalibrateProjector: Capturing 60 tie point frames… done
Tie point: 819.5, 192.5; 19.4192, 0.522661, -55.114

BoxLayout.txt outputs taken right before this calibration attempt (sea level changed from -90 to -105):

(-0.0216684, -0.0394426, 0.998987), -105.8983
( -46.0027, -32.887, -103.57)
( 47.7056, -29.9049, -104.008)
( -48.19, 39.7827, -104.159)
( 48.9422, 38.9245, -101.912)

I’m not sure what other information might be helpful. The projector is a BenQ MW632ST, the keystone hasn’t been adjusted. I didn’t do the glass checkerboard calibration step for the Kinect, as it said it was optional.