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Exposed edge of negative calibration corner

The place for questions, problems, comments and tips regarding the camera calibration.

Exposed edge of negative calibration corner

Postby evox » Fri Jul 10, 2015 8:59 pm

I'm working on my first calibration corner. The plan is to scan large objects (such as cars). Running david4.

I have ~1.5" thick aluminum honeycomb paneling and am making a negative corner. The surface will be painted matte white with vinyl-plotter cut markers.

My question is about finishing the external edge where the panels meet up. This edge area has the highest chance to have planar distortion for the panels. Ideally I would have aluminum inserts machined, but I would like to avoid the cost. I am not relying on this edge joining for structure.

Question 1: will david4 software ignore this edge for shape and color?
Question 2: The calibration panels must be straight and perfectly planar to all the software to correct for lens/projector distortion. I've seen the advice of adding black strips to reduce reflection on normal/positive corners...does david4 ignore the joining edges? Whats the tolerance?
Question 3: How straight do the joining edges of the panels need to be? How much gap can exist between the panels (1/16"? 1/8"? 1/4"? varying gap?) Assuming the panels are fixtured to be perfectly 90degrees and the marker grids on each panel have no rotation relative to each other.

In the attached image-
Option1 I think is the best, but most difficult to fabricate, and there is a high chance that the extend section of 'skin' (on the vertical part in the picture) will have some waviness. Also, the edge of the extended skin will not be perfect.
Option2 is the easiest to fabricate if the honeycomb edge must be sealed, but will add a (~1/8") step where the bracket meets the paneling. Will david4 ignore this area (see question 2 above)
Option3 is very little work, and leaves an exposed honeycomb edge (on the horizontal panel in the picture). Will the complex shape of the exposed honeycomb (I can paint matte white) cause calibration issues?

methods of joining aluminum honeycomb 90degrees
Scanning + reverse engineering cars and car parts
David4, Imaging Source DMK 23UM021, Computar 12mm lens, Acer K335, Aluminum honeycomb calibration panels
Arizona, USA
Posts: 2
Joined: Thu Jun 18, 2015 3:42 pm

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