Technical implementation of MINI

Hello Revopoint Team!

I have a question about technical implementation: how do you projecting patterns?

I mean - i saw TI DLP Lightcrafter EVM (+ DMD device) - it is pretty massive thing with big optics system, i saw analog projector with static line pattern on film - it is also pretty big.
So, i’m wodering - how it is possible to make 3d scanner in such small case.

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What I have read is that Revopoint has designed a custom IC (maybe an FPGA, but I really don’t know) to combine the specific needs of the Binocular Structured Light technology for 3D Scanning.

The development process does require a lot more effort and expense up front, but it appears to be paying off.

What is IC? I’m familar with structured light technology. I mean is projecting part regular DMD + simple lens (like in pocket projectors)?

Integrated Circuit. CPUs, RAM, Field Programmable Gate Arrays (FPGAs), Voltage Regulators, etc. can all be implemented as ICs.

Also it is interesting - what is resolution of projected image?

It is structured Light projector . Patterns are usually generated by passing light through a digital spatial light modulator , typically based on one of the three currently most widespread digital projection technologies but if it is DLP, LC or LCOS I can’t tell you 10O%, however it is likely to be DLP .
DLP would also fits the best in this size scenario and the way it is working .
The pattern is not static and change from left to right constantly.

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There is no image resolution as it does not project any image but moving fringe pattern , you have only 20cm at max between the scanner and the object to scan anything , so the captured area is very small .
How closer the object , how finer the fringe pattern and the minimum distance is 10cm.
If there was an image , they could have a bigger range for scanning as the image could be adjusted for different distances, but it is one static light pattern projection , how far you go how bigger the pattern , and how bigger the pattern how less accuracy you will get .

So, it is neither gray code no phase shift patterns? Just single pattern? Now it is clear, why it is so fast.

Yes it is phase shift fringe pattern, but the light source and the pattern are 2 separate things, I believe the pattern is on the micro mirror . Since the light source do not have any pattern and it’s direction is controlled by the micro mirror .
It do shifts 10 times per second as I made slow motion video to see what is happening from curiosity.

I don’t know yet exactly what kind of LED blue light it is , it behave as a black light but it is not , yellow surfaces absorbing it completely for that reasons any yellow surface are not visible by the scanner and literally glowing like under black light .
It also have issues with any color surface that has yellow in it like golden colors, brown warm reddish and green . However works fine with blue, magenta gray and white colors .

What make me thinking , how it going to scan colorful object with the RGB camera for texturing if it can’t see most of the basic colors , usually blue light scanners have also infrared light for support ,

Thanks. Now it is clear.

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That seems really bad for a scanner aimed at scanning jewelry…
How does it behave with gold ?

There are no 3D scanners that scan polished silver or gold , since metals are reflective , so you need to use specific spray for scanning jewelry.

I saw today preview of MINI with RGB camera and it looks like the final model will not have any color scanning issues anymore like the first prototypes.

So I would be less concerned about this issue for now .

Still you need to use 3D spray on any reflective, glossy or transparent surfaces you plan to scan with .

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hi @PopUpTheVolume
Do you know why they use more IR for what purpose?

Hi @npsg IR is best when it get about surfaces , as it can scan any colors including black cotton or velvet as long it is not synthetic .
It can scan any skin color , eye friendly , invisible and less destructive to delicate objects . It can scan well bigger objects .
It is not much affected by LED light , and in combination it can be used for capturing color textures at the same time as it don’t alter the original color , many blue light scanners using IR in combination to capture objects in full colors .

Blue light is more sensitive to LED but scan better with day light than IR, it can’t scan any colors that do not reflect blue light like yellow, brown, orange , red , green and any other color that is mixed or based with yellow.

It scans perfect white, gray, magenta, blue and most cool colors .

BL can’t scan dark skin , so dark brown and black skin can’t be scanned since it absorb blue light , you can’t scan black Cotton or black velvet , black or dark hair .

However BL is much more sharper so finer and smaller objects and details can be captured , it penetrates also much deeper the surface for better fine details scanning .

So if a good scanner is armed with both IR and BL you can get best results in any situation with any object .

For that reason MINI is not a replacement for POP2 as it can’t do what POP2 can do and vice versa, but it is simply a great companion.

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