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Fiducials
peter heim from Australia  [2 posts]
14 year
Hi All
I have just noticed a small problem with RR and fiducials when i view a fiducial the x rotation varies about 6 - 10 degrees which results in a variation off up to 1 meter in x cord calcs i have tried diffrent cameras, diffrent computers diffrent resulations with the same result I tried a 20 frame averaging while the average variation is only 200 300 mm with the odd 1+ meter error. the distance to fiducial is 3.5 meters and the size is 9 to 10% even at 1 meter distance i still get 3-4 degrees error has anyone else noticed this?
Anonymous from United Kingdom  [99 posts] 14 year
Yes, the orientation of the fiducial fluctuates with an uncertainty of +- 4 degrees at 1 sigma.  I am not sure how the variation in the orientation of the fiducial effects your x coordinate calculations(What is the x coordinate relative to the image plane?).  I usually just find the coordinates from the center of the fiducial which is largely independent of orientation.   Could you explain how you are doing your calculations?  Maybe give us an annotated image?

Thanks!
mmason  
Anonymous 14 year
Peter,

As mmason mentions, any chance we could get two images posted here of the same fiducial where this uncertainty exists? That would allow us to do some checks to see why this is the case.

Thanks,
STeven.
peter heim from Australia  [2 posts] 14 year
I think i have solved the problem i had the fiducial laminated and it reflected light and shadows. I changed to a new fiducial and the error is now about 2 degrees. i tried to take some screen shots but they only showed about .5 diffrence. In a few days i will change back and post the screens shots

regards Peter

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