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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Vernier explanation
From: Peter Monta
Date: 2022 Jun 27, 03:15 +0000
From: Peter Monta
Date: 2022 Jun 27, 03:15 +0000
Hi Don,
Parallax in the camera view is not likely. The owner posted this inquiry specifically because he could not detect any difference in the spacing of the two scales by eye.
Hmm. Could the vernier have been mis-engraved, perhaps by configuring the dividing engine with settings intended for the arc? How would that have gotten past final quality control?
I'm tempted to do some analysis of the image, but that would have to estimate the camera pose and a good subset of the tick marks. Four engraved circular arcs are also available as constraints. Alternatively, could the owner supply a few more photos, for example with the camera directly above the vernier's 0, 2, 4, 6, 8, and 10 (using a fixed index-arm setting of course)?
Cheers,
Peter
