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That does not look like a 10 micron scan... Edit: Here is the source for the claim: https://www.reddit.com/r/OpenScan/comments/gfottc/10_micron_accuracy_with_

by ohazi 6y ago

That does not look like a 10 micron scan... Edit: Here is the source for the claim: https://www.reddit.com/r/OpenScan/comments/gfottc/10_micron_accuracy_with_the_new_pi_camera/ https://www.reddit.com/r/OpenScan/comments/gfottc/10_micron_... It seems this might be the theoretical error that you can get when the system can identify a feature perfectly, and when it gets a usable reflection from that point at enough angles. But this is not the case for most points on any real object (i.e. not a chalk-coated gauge block), so you're definitely not going to get a model where the maximum error is 10 microns. The results are certainly impressive, but hackster.io is taking liberties with that headline. It's not a realistic accuracy and the author of the project doesn't really seem to be making that claim.

deleted 6y ago
[deleted]
tofof 6y ago
I don't think I follow your reasoning about 'real objects'. Real objects can (and usually must) be coated with scanning sprays, like the Aesub Blue the author notes in several places that he uses. These sprays then vanish completely from the model after a few hours. The entire point of these sprays is to ensure that your model is covered in features that are perfectly identifiable. The author makes the 10 micron claim in several other places, including https://www.reddit.com/r/photogrammetry/comments/k5dbtk/automated_scaling_accuracy_of_001mm_at_10cm_object/ https://www.reddit.com/r/photogrammetry/comments/k5dbtk/auto... about a totally different model. That thread discusses ways to quantify accuracy and generally agrees that the rig should not be capable of such feats. But then there are images like https://www.reddit.com/r/OpenScan/comments/ls17tt/closeup_of_the_3d_scanned_raspberry_pi_why_is_it/ https://www.reddit.com/r/OpenScan/comments/ls17tt/closeup_of... in which his scans are picking up the silk screening on the surface of the board, which at least lends some credence to the idea that he's getting 10 micron accuracy.
- pmiller2 6y ago
  This might be a good place to ask, because I've been wondering about this for a while: do any of these scanning sprays react with copper, silver, or gold? I can't ever find an actual ingredients list for them, and all the MSDS ever lists is various hydrocarbons, which I know won't react.
  - thomas_OpenScan 6y ago
    Cyclododecan has been the industry standard for vanishing 3d scanning sprays, but as Cyclododecan is no longer available from the textile industry, this kind of spray does not exist anymore. Aesub Blue is a rather new product from a young German company. I have met the founders last year and they are really professional and transparent. Just check out their documentation. To be fair, as the product is so new, possible interactions with materials are still not perfectly understood. But from what I have seen, the feedback from the professional scanning community is very positive.
wyldfire 6y ago
I think most 3d imaging stuff uses MTF [1,2] to measure the real spatial resolution performance. [1] http://www.imagescienceassociates.com/mm5/pubs/What_is_an_MTF_and_Why_You_Should_Care.pdf http://www.imagescienceassociates.com/mm5/pubs/What_is_an_MT... [2] https://iopscience.iop.org/article/10.1088/1361-6501/aa9aa0/meta https://iopscience.iop.org/article/10.1088/1361-6501/aa9aa0/...
thomas_OpenScan 6y ago
Hi, this is Thomas, the guy behind OpenScan. I really would like to clarify several things. - I have never made such a bold claim of 10 micron accuracy for the device. Yes, I made several scans, where the accuracy is quite good, but I would never say, that this can be reached under all circumstances. - To be fair, I have been kinda click-baity in the past on a handful occasions, but everyone who is doing at least 5mins of research will find for instance this one here: https://en.openscan.eu/quality https://en.openscan.eu/quality - Comparing this 100-200€ device with an industrial 3d scanner is like comparing a hobbyist 3d printer with a highend injection molding machine... Anyway, feel free to discuss and ask me anything about it :)
- ohazi 6y ago
  Really nice work, by the way... I hope my comment didn't seem overly harsh. I know that doing testing with gauge blocks is part of the process and I really only took issue with the hackster.io headline.
  - thomas_OpenScan 6y ago
    Thank you and no worries, I absolutely agree with your valid criticism. Later this year I will get some more CT reference scans to compare my results too. I think that this will give some better insights. By the way, even on the professional market there seems to be no „universal“ benchmarking procedure to compare the various mid-range scanners (1-20k€). So this is a very interesting discussion point

by ohazi 6y ago

deleted 6y ago

[deleted]

tofof 6y ago

I don't think I follow your reasoning about 'real objects'. Real objects can (and usually must) be coated with scanning sprays, like the Aesub Blue the author notes in several places that he uses. These sprays then vanish completely from the model after a few hours. The entire point of these sprays is to ensure that your model is covered in features that are perfectly identifiable. The author makes the 10 micron claim in several other places, including https://www.reddit.com/r/photogrammetry/comments/k5dbtk/automated_scaling_accuracy_of_001mm_at_10cm_object/ https://www.reddit.com/r/photogrammetry/comments/k5dbtk/auto... about a totally different model. That thread discusses ways to quantify accuracy and generally agrees that the rig should not be capable of such feats. But then there are images like https://www.reddit.com/r/OpenScan/comments/ls17tt/closeup_of_the_3d_scanned_raspberry_pi_why_is_it/ https://www.reddit.com/r/OpenScan/comments/ls17tt/closeup_of... in which his scans are picking up the silk screening on the surface of the board, which at least lends some credence to the idea that he's getting 10 micron accuracy.

pmiller2 6y ago
This might be a good place to ask, because I've been wondering about this for a while: do any of these scanning sprays react with copper, silver, or gold? I can't ever find an actual ingredients list for them, and all the MSDS ever lists is various hydrocarbons, which I know won't react.
- thomas_OpenScan 6y ago
  Cyclododecan has been the industry standard for vanishing 3d scanning sprays, but as Cyclododecan is no longer available from the textile industry, this kind of spray does not exist anymore. Aesub Blue is a rather new product from a young German company. I have met the founders last year and they are really professional and transparent. Just check out their documentation. To be fair, as the product is so new, possible interactions with materials are still not perfectly understood. But from what I have seen, the feedback from the professional scanning community is very positive.

wyldfire 6y ago

I think most 3d imaging stuff uses MTF [1,2] to measure the real spatial resolution performance. [1] http://www.imagescienceassociates.com/mm5/pubs/What_is_an_MTF_and_Why_You_Should_Care.pdf http://www.imagescienceassociates.com/mm5/pubs/What_is_an_MT... [2] https://iopscience.iop.org/article/10.1088/1361-6501/aa9aa0/meta https://iopscience.iop.org/article/10.1088/1361-6501/aa9aa0/...

thomas_OpenScan 6y ago

Hi, this is Thomas, the guy behind OpenScan. I really would like to clarify several things. - I have never made such a bold claim of 10 micron accuracy for the device. Yes, I made several scans, where the accuracy is quite good, but I would never say, that this can be reached under all circumstances. - To be fair, I have been kinda click-baity in the past on a handful occasions, but everyone who is doing at least 5mins of research will find for instance this one here: https://en.openscan.eu/quality https://en.openscan.eu/quality - Comparing this 100-200€ device with an industrial 3d scanner is like comparing a hobbyist 3d printer with a highend injection molding machine... Anyway, feel free to discuss and ask me anything about it :)

ohazi 6y ago
Really nice work, by the way... I hope my comment didn't seem overly harsh. I know that doing testing with gauge blocks is part of the process and I really only took issue with the hackster.io headline.
- thomas_OpenScan 6y ago
  Thank you and no worries, I absolutely agree with your valid criticism. Later this year I will get some more CT reference scans to compare my results too. I think that this will give some better insights. By the way, even on the professional market there seems to be no „universal“ benchmarking procedure to compare the various mid-range scanners (1-20k€). So this is a very interesting discussion point