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Two camera one projector with DAVID

Problems, solutions and discussion about scanning with a video projector and stripe patterns.

Two camera one projector with DAVID

Postby ITS » Mon Apr 21, 2014 4:45 am

Guys,
I need some help on setup with two camera and one projector, hope anyone with experience could provide me some advice. I list some of my questions as below:
1. So far, we all know the current David does not support dual camera setup, if I have to use two cameras, do I need two copy of DAVID? If so, do I need to buy two license?
2.The dual camera system may be supported in David 4.x, anyone knows if the coming SDK will support dual camera setup?
3. How to calibrate two cameras? Do I put the calibration corner at the same location and calibrate each camera? or I can calibrate each camera separately by putting calibration corner at different location? I need to fuse the scans from each camera, this will need both scan with same coordination system (I think, not sure though). I want to use the best calibration method which assure the depth info in the scan from each camera should be accurate for each identical point on the object.
4. The main purpose for having two camera is to see more aspect of the object by not moving camera or object, another reason is to take scan from different angle so that it may help to reduce the direct reflection on shiny surface. Anybody knows whether this will help on shiny surface?
5. I think I will save scan from each camera and fuse them by using shapefuse function from DAVID. Is there any potential issue with fusion?
Any input is highly appreciated. Thanks on advance,
Hongsheng
ITS
 
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Re: Two camera one projector with DAVID

Postby MagWeb » Mon Apr 21, 2014 11:45 am

Not tried this yet for I do not own two cams of the same quality (which should be necessary to use the same projector brightness for both cams):

So in theory it should work this way:
Mount cams A and B + the projector on one rig (at almost the same distance left/right or above/below of the projector).
Adjust both cams onto the same calibration corner.

Copy the DAVID directory to be able to save both calibrations (no second license needed).
Run two instances of DAVID (one from directory A, one from directory B)
Make sure that both instances use the same SL-settings.

Use cam A with DAVID A and cam B with DAVID B
Calibrate both DAVIDs (one after the other)
As long you use to scan with DAVID B after a scan with DAVID A there should be no problem with the projector handling.

As soon as you try to run both DAVIDs at the very same time there should be a problem with the two projections.
A possible solution might be to set DAVID A to use the second screen (=projector) while DAVID B uses the main monitor (you may minimize that projection window).
Now to synchronize both DAVIDs you might use the COM communication feature:
Build a virtual com port pair (maybe using com0com). This creates a com port pair (maybe COMX and COMY) on your system where the messages are passed through.
Enable communication in both DAVIDs
Set DAVID A to use COMX while DAVID B uses COMY
Now if you click StartScan on DAVID A it sends a message, DAVID B recieves this as a command to start to scan as well.... This should work...

Gonna dig deeper into that with my limited hardware... stay tuned
MagWeb
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Re: Two camera one projector with DAVID

Postby ITS » Mon Apr 21, 2014 3:22 pm

MagWeb, thank you so much for your quick response and detailed instruction. I am going to try running CAM B after CAM A for now. Eventually, I need to sync two cameras. Please keep me posted. Thanks again,
Hongsheng
ITS
 
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Re: Two camera one projector with DAVID

Postby MagWeb » Mon Apr 21, 2014 6:46 pm

Ok, some further things about sync problems:

The thing about connecting two instances of DAVID via a virtual COM-port pair works. You've to set NewLine in Communication/COM to "10" in both instances to make the DAVIDs understand the commands/messages from each other. Next thing you've to do is to remove the Start message in DAVID B to avoid an invenite loop of changing "S" messages/commands.
So far so good. I said that I've no equal cams at hand and I cann't get my two different devices to run on an equal framerate. There's also no command to use a "N" - NextSLPattern message of B as a command for the first instance to switch the projection. This means that both processes do run out of synchronicity if their input framerates aren't equal and DAVID B's result will simply be garbage. This may be less if equal cams at different USB controllers are used.
Another solution might be to use ImageContent SyncMode in SL settings plus: If the cams were not running a live stream but were used via their triggers (if they own one) one could use DAVID A's "N" messages to trigger both cams were the second cam's output feeds DAVID B... Another thing to try.

Sooner or later DAVID is going to support 2 cams, sure. This instances way will always duplicate...
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Re: Two camera one projector with DAVID

Postby ITS » Mon Apr 21, 2014 8:16 pm

MagWeb, Thanks again. I think for now the easiest thing for a newbie like myself to do is to scan CAM B after CAM A :) . By this way, it is not necessary for me to have two identical camera whose setting is also identical. As long as the cameras are with same resolution, it should not affect scan result and shapefuse, right? The problem is how to let CAM B knows that it is his turn to scan after CAM A is done? This can be done manually in-between two instances of DAVID, it will be great if we could issue a Command from DAVID A to DAVIB B. One more potential issue to run two DAVID instances at the same time is my hardware, i.e. computer system, I plan to use high level tablet (something similar to ultrabook) to complete the scan, it may cause some performance issue due to memory and CPU limitation if two scan going at the same time. And many of those devices may only have one USB controller. The cameras I have does support external trigger capture, I am using Basler acA640-90gm, it is 640x480 GigE Vision camera, and support DirectShow filter, my DAVID works fine with one camera, will need to switch to USB3 version after testing the setup. DO you guys foreseen any potential issue on the setup?
Thanks,
Hongsheng
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Re: Two camera one projector with DAVID

Postby hunkatibor2 » Tue Apr 22, 2014 6:27 am

Hi ITS
Argue, if your system camera with a projector puts rail, displacement and two items for the control of this fuse it and get good results more simply.
  The two camera is the texture of the importance of accuracy, the test will not improve quality.
Tibor
Intel Xeon E5410 2.33GHZ 16GB RAM Windows 7 64bit David 4.5.0
2 Basler A622F camera 2 Tamron Asfirical AF 28-80mm lense
LG DLP Projector PF1500G Canon D40 Tokina 17-70mm 1:2.8-4,5
Humanti Calibration panel system and Alignmed&Two camera
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Re: Two camera one projector with DAVID

Postby MagWeb » Tue Apr 22, 2014 8:25 am

Sure, simply by turning your rig 180° degree around the projector you'll get the same.

Against this attempt:
A clever way to compare the input of two cams on the same instance will give the possibility to improve the scan's quality.

Running two or more synchronized instances provides the possibility to build a system that grabbs a object as fast as possible. This is not a question of quality and effort but of speed.

And it works even for very different cams as a Ueye and a good old DAVID ccd cam. As a proove of concept (Simultaniously scanned the way described above):
Attachments
Simultan.jpg
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Re: Two camera one projector with DAVID

Postby hunkatibor2 » Wed Apr 23, 2014 6:25 am

Hi MagWeb
two calibration did?
Tibor
Intel Xeon E5410 2.33GHZ 16GB RAM Windows 7 64bit David 4.5.0
2 Basler A622F camera 2 Tamron Asfirical AF 28-80mm lense
LG DLP Projector PF1500G Canon D40 Tokina 17-70mm 1:2.8-4,5
Humanti Calibration panel system and Alignmed&Two camera
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2 Cams 1 projector and more

Postby milz » Wed Aug 20, 2014 12:08 pm

heho
related to this topic viewtopic.php?f=15&p=30775#p30736 and my own ideas
i started this thread to discuss about multicam / multiprojector systems.

Trigger and capture the cams is not the problem. here we can work with com2com and some
USB hubs.
But how to trigger the projectors. We need a HDMI matrix which can switched by an external
trigger over USB/Serial/I2C something like this.
Or many PC / Laptops.

I work atm on my one projector two cam system and tested with 2 regular systems aswell.
I will order hardware for a third system soon.

mfg milz
Xeon x5650@4ghz
Cam : USB2 CCD 1024x768 / USB3 1280x900
Laser : LC532-5-3-F(16x65) Focusable Green
Projector Acer X110P / Acer K132
dControl one David control box + Turntable + automatic texture lights
mooooom bathroom!!!!!!
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Re: 2 Cams 1 projector and more

Postby MagWeb » Wed Aug 20, 2014 3:45 pm

Hi Milz,

at two cams: there's no need to synchronize the projections, you may use one of DAVID A. DAVID B waits for new content.
See: http://forum.david-3d.com/viewtopic.php?f=15&t=6102&p=29727&hilit=One+Projector+Two+Cameras#p29726

IMO more than two cams + 1 projector don't make much sense. If camA+projector+camB are on one axis theres nothing lightened by the projector which one of the cams cann't see. (one may use a third cam or even more to grab controll scans to minish noise and distortions but 2+ cams cann't see not more than two).

The only way to use more than one projector at the same time is two splitt their light in an R, a G and a B channel, while the cam(s) belonging to one projector need a fitting R, G or B filter. This way you could use 6 cams and 3 projectors at the very same time. If you do not want channel splitting you have to to use the systems one after the other (which is the same as turning the object but rather costly)

You may also splitt a projection via a mirror system to get two aspects of a single cam using such splitting:
http://forum.david-3d.com/viewtopic.php?f=15&t=3881&p=20678&hilit=SL+mirror#p20619
Just an idea wasted in the forum's dust.
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Re: 2 Cams 1 projector and more

Postby milz » Wed Aug 20, 2014 4:25 pm

hi gunter

Sure, with one projector no hdmi matrix is needed. but whats about 4 8 or at least 24 systems for full body capture. :D
A rig like this is much cheaper than a DSLR Rig with 60-90 1100D or D3200. a little bit slower and not the best texture
but at 1/3 price.
A system with 3 projectors and 4 cams would be nice for face scanning.
left / right / top / thin cam
top/bottom vertical calibrated / left right horizontal....
some 120hz projector and 60fps usb3 cams....
thats what im dream about atm -) perhaps David will sponsor me
1-2 two systems for testing this :twisted: :roll: :shock: :lol: -)

Edit: perhaps a mod can move the post to the other thread. sry for the double posting. did not search it before post.
shame over me -)

mfg milz
Xeon x5650@4ghz
Cam : USB2 CCD 1024x768 / USB3 1280x900
Laser : LC532-5-3-F(16x65) Focusable Green
Projector Acer X110P / Acer K132
dControl one David control box + Turntable + automatic texture lights
mooooom bathroom!!!!!!
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Re: 2 Cams 1 projector and more

Postby hunkatibor2 » Wed Aug 20, 2014 4:31 pm

Intel Xeon E5410 2.33GHZ 16GB RAM Windows 7 64bit David 4.5.0
2 Basler A622F camera 2 Tamron Asfirical AF 28-80mm lense
LG DLP Projector PF1500G Canon D40 Tokina 17-70mm 1:2.8-4,5
Humanti Calibration panel system and Alignmed&Two camera
hunkatibor2
 
Posts: 1408
Joined: Tue Mar 16, 2010 4:26 pm
Location: Hungary

Re: 2 Cams 1 projector and more

Postby MagWeb » Wed Aug 20, 2014 5:44 pm

Tibor, as far as I understand this setup of the HDI120:
It only demonstrates that you can plug 6 devices to a single software instance. Their scanners are pretty fast but as said: as long as you do not find a way to tell each camera which projection source is the right one you cann't use SL projectors simultaniously(they merge their light on the object)! Guess they simply run one device after the other and merge the results in a single instance of their software.

Milz, which thread do you mean to move this one to?
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Re: 2 Cams 1 projector and more

Postby milz » Wed Aug 20, 2014 6:25 pm

gunter this one ... same topic
viewtopic.php?f=15&t=6102&p=29727&hilit=One+Projector+Two+Cameras#p29726
yes gunter this is what they do. they trigger the devices once by once.
the arctec sytem run with 12 or 16 system. they trigger more then one projoctor at the same time.
allways sides which not disturb the other scan....

hunkatibor2
i mean more stuff like this
https://shapify.me/main/booth
http://www.ten24.info/ten24/wp-content/ ... er_001.jpg
Xeon x5650@4ghz
Cam : USB2 CCD 1024x768 / USB3 1280x900
Laser : LC532-5-3-F(16x65) Focusable Green
Projector Acer X110P / Acer K132
dControl one David control box + Turntable + automatic texture lights
mooooom bathroom!!!!!!
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milz
 
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Joined: Wed Jul 15, 2009 12:24 pm
Location: Germany Cologne

Re: Two camera one projector with DAVID

Postby MagWeb » Wed Aug 20, 2014 7:29 pm

Ok Topics merge now!

I wouldn't call Artec scanners SL. Their technic seems to be similar (or equal ?) to Primesense sensors (as Kinect1, Xtion, Carmine).They are merging 1 frame "scans" on the fly (or postprocessing them). They seem to use a pulsing (?), single(?), arbitrary(?) IR-pattern attempt - but maybe I'm wrong. Yes it works to use several such devices (even Kinect1s).
Structured Light Scanners need to have known structure in the light. You loose this known structure projecting two or more structures onto the same surface. Try it (you may use a mirror as faked second projector).
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