Blinds Feeder will not calibrate

[David Griffiths]

I have relocated my two blinds feeder arrays slightly and now I cannot get either of them to calibrate.  It fails with an error message that says 'Blinds feeder 1 S1 - fiducial not found'. Mainly it fails on the first fid but sometimes gets onto the second fid. I am seeing the diamond displayed each time.

The log entry looks like this:

2021-10-09 16:35:12.353 BlindsFeeder$FindFeatures DEBUG: dismissed fiducal candidate: result { {965.2501220703125, 554.7500610351562} 33x34 * 45.0 }, mmSize (1.394384, 1.427273, -0.000000, 0.000000 mm)

I am guessing it thinks the fiducial is too small (on a friend's machine he is seeing dimensions around 1.7mm), What size is it expecting? Is this configurable? (I have looked in machine.xml and found fid-loc-max-passes="3" fid-loc-tolerance-mm="0.5" but nothing relating to fid-size)

I have checked my pixels per mm.

This was working OK for a couple of weeks - not sure what has changed apart from relocating the arrays. Perhaps my hole size was always marginal?  I don't want to take the knife to them yet though.

[ma...@makr.zone]

Hi David

The fiducial should be 2mm and it accepts down to 1.4mm, up to 2.3mm, both limits are hard-coded. As you see in your result, it is borderline, i.e. it will work/not work unpredictably.

I suspect it's actually good to not be recognized, you may have slightly color-tinted shadows inside the fiducial that are not excluded by MaskHSV (the light is shining through the green PETG and tinting the shadows). Shadows must not be recognized as part of the fiducial, they will throw off accuracy, as they are not necessarily symmetrical.

You are on the testing version, right? The following is only available on testing:

First, if not yet done, switch off USB Automatic White Balance and apply the OpenPnP White Balance? Why? and How? See here:

https://github.com/openpnp/openpnp/wiki/Camera-White-Balance

It is the basis for stable green-screening.

Maybe you can then tune the MaskHSV yourself, to exclude the shadows in the fiducial. When the background of your fiducial is very reflective, you might have to color the inside of the fiducials with a complementary color (red/blue/magenta) or black. Just use a fine permanent felt marker.

If you need help with MaskHSV, please do the following:

1. Place the camera over the fiducial, as the calibration would.
2. Double click the camera view, to save a snapshot
   
3. Send the snapshot from .openpnp2/snapshots to me
   
4. Edit your pipeline, copy & paste and send to me

_Mark

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