ArUco 3x3 generator?

I’m very interested in the ArUco targets. Has anyone got any recommendations for 3x3 ArUco generators?

Even just the pattern for 3x3 markers from 1-10 would work for me.

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You can use the utility provided by Find GCP
Follow the install part then use the dict_gen_3x3.py script.

It is very easy to do. Few and straight forward steps for install.

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Got it. A bit of faffing around as I’m not used to Python. Apparently Pil won’t install on python3 (Use Pillow instead) and imageTk wouldn’t install either. I’ve generated the targets now. Next thing I’ll look at is designing some 3D printable targets.

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Results :smiley:

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I’ve never really used GCPs, but from what I gather the points themselves first need to be registered by a high-quality GPS location or something, and a human has to identify which pictures have the points in a file which is supplied separately to ODM. Is that the case here? Does using these generated figures take the human out of the loop?

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Yeah, it’s super sweet: automatic extraction of the locations of GCPs in each image in which they’re extant (pixel and line position within each).

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That first part - locating the GCPs with GNSS is (almost) always required (exception being things like Aeropoints). However, the tedious aspect of registration is the manual identification of the GCPs in images. This should automate that aspect.

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Wow this is amazing. What’s the minimum reasonable pixel size for these targets? I’ve seen some square bathroom tiles that are like four inches wide, it might be fun to make these and install them in the yard.

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I think around 300x300mm for phantoms flown at 50-60m (gsd ~1.5cm/pixel). There’s some more info elsewhere in the forum.

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The FindGCP landing page has some info:
https://www.opendronemap.org/findgcp/

They also provide a link to this great utility:
http://www.agt.bme.hu/on_line/gsd_calc/gsd_calc.html

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When I ran the calculator on the landing page, the ArUco width for my drone at 125m for a 3x3 marker is 42cm. Assuming that’s a minimum and that it includes the border, then individual pixels would be a little under 4" which is a fairly common size for tile. If I can find a few stacks of matte black and grey, I’d be in business. Nice.

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Just try to get matte tiles. Shiny ones can be problematic.

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Or take a sander to them or flip them shiny-side down.

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Tiles are expensive. :slight_smile:

I spent some time contacting local tile shops, and I’ve narrowed my choices down to two tile styles: Sahara and Wave. The per-tile cost is on the order of $5 each after tax, which makes each 5x5 marker about $125 so I’d like to get it right the first time. The Wave has higher contrast, while the Sahara appears to be more uniform on the dark tile. Any thoughts on whether either issue will make a difference?

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