Face scanner - Prototype

[Exhale]

OMG...!

Since I lost track on this topic, you made great improvement Mfranquelo...!  Congrat.
Can't wait to see some scans.

[Marcel]

Out of curiosity: why do you rotate the cameras up/down like this? I would expect that it would be mechanically much easier to rotate them around your subject (from left to right)? (with the pivot of the arm located above your head).

[Exhale]

H?mm,  yes...  Earlier, I was thinking the same. I think it was for only demonstration. ?

[Lambo]

This looks amazing! Pretty nice rig.
Whenever you get a little more money saved, maybe you can think about constructing most of the stuff in carbon fiber since it is getting cheaper and it will help reduce the weight of the complete system and therefore the requirements for the stepper motor, bearings, etc.
It will also make it easier to rotate fast and stop fast without much vibration.
Leo

[Mfranquelo]

Lee - It does indeed, someone from my work mentioned this today dont miss me if someday i disappear...

I will prepare a home made video of the working system, tomorrow im going to test the optic sensors for triggering...

Wow thats an amazing panoramic robot marcel! i have a CLAUSS system on my home, but its WAY too expensive for what it does...
- Personally i dont know much about about automation systems, just the basics:
Im using a programmable inverter to control de servomotor, with an angular encoder attached. Its way too complicated for this task i know ^^. Im not the best person you can ask about the stepper motors. (I know that Maxon is a good servomotor manufacturer although).

- indeed Lambo, im just aiming for functionality right now, getting the most out of the cameras speed has been complicated for me as well as programming the logic of the micro controller, (im still a beginner in this field  )

[Mfranquelo]

Out of curiosity: why do you rotate the cameras up/down like this? I would expect that it would be mechanically much easier to rotate them around your subject (from left to right)? (with the pivot of the arm located above your head).

- Well thats a good question, at the first stage of the prototype i thought that the gravity force could help the system... so i would just need some kind of hydraulic brake... But things got more complicated so i decided to use a servomotor, i might change it on the near future... (I have another concept drawing made on solidworks ready)


* Yeah its just for a demonstration for a surgery convention in Prague.
* we've developed a laser scanner as well, if you're curious have a look at www.factum-arte.com all the work we're doing is mainly for restoration and conservation purposes.

[Mfranquelo]

https://www.dropbox.com/sh/3mj3f4k1z5wx2fv/1ssE0x86tM

  - Movement takes 3 seconds right now - for testing purposes, it will be 2.2 seconds soon.
Flashes are not in position, i was building my own micro flashes, (with just the bulb and the capacitor) but i got electroshocked, never manipulate a flash if you dont know perfectly what youre doing! ... so im using comercial ones at the moment ..

[Infinite]

https://www.dropbox.com/sh/3mj3f4k1z5wx2fv/1ssE0x86tM

  - Movement takes 3 seconds right now - for testing purposes, it will be 2.2 seconds soon.
Flashes are not in position, i was building my own micro flashes, (with just the bulb and the capacitor) but i got electroshocked, never manipulate a flash if you dont know perfectly what youre doing! ... so im using comercial ones at the moment ..

It looks very smart but 2.2 seconds is a long time in the world of face scanning. You can see the face moving even from this distance. Do you find this an issue during build? How do you solve that?

[Mfranquelo]

Building is perfect, no misalignments.  (for neutral faces) i dont know for expressions that are hard to hold... I can post results when i attach the flashes next week.

In theory : If the pixel resolution used by Photoscan for building is less than "the resolution of the movement" then no building error should occur. Since when using "High" the image is down-sampled to 50% (i think?) the movement is not noticeable in pixels. (Alexey correct me if im wrong) 
Anyway building looks good.

The only critical thing in this system is DOF and not blinding the subject with the so-close flashes. I might change to super-luminescent LEDS used like a flash, but i dont have enough budget for that yet.

- Of course its never better than instant system, but just cheaper... 

[Exhale]

I was experiencing this object movements & alignment with Agisoft®.  I believe, PhotoScan® can correct some movements at the alignment, unless there is no face movement such as lips, eye-browns..etc.  Mfranquelo , also you use something to make stabilization for the head, don't you?   

What do you think Lee ?   
I don't know perhaps you made the experiment what I'm going to write.. Let's imagine you have 20 cameras, 10 for lower face, another 10 for upper face. Make 2 different bunches with separate trigger. Trigger the first bunch, and a bit later (2-3 sec) trigger the second bunch.  Have you ever tried sth like that?  In this case, Does small movements effect so much? 

[Mfranquelo]

Not yet... i was planning to build a head stabilizer like on the old photographic times. (more ergonomic ofc...) but just seeing my tests i dont need it, it is useful for placing the head "on the recording volume" however.