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DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

The place for questions, problems, comments and tips regarding the camera calibration.

DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby Lunat1c » Sat Nov 09, 2013 2:03 am

-As you can see in the first 2 images how the webcam bends the scan like the sun bends the light.
-I usually go on with this, but I wonder now, does this affect anything? What should I do?
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby Lunat1c » Sat Nov 09, 2013 2:39 am

-Is this misalignment because of that?
-If not, what is the cause of this misalignment between the first and last scans? My calibration board seems to be precise...
-In order to fill my camera view with dots and don't let the webcam see past the points, I accept the shadow of the cam fall on the board. Because some of it gets in the way of the projector's light.
-To get rid of the shadow I have to pull the camera back and zoom instead. But if I digitally zoom wouldn't it be bad for the scan?
-I must either choose to zoom, or accept that the cam see beyond the dots, or accept that it's shadow fall on the board. Which one is better? What would you choose dear pro Davidians?

Best regards,
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby Lunat1c » Mon Nov 11, 2013 3:13 pm

-Come on Davidians, nobody gives any suggesstion or information...
-And yes shadow of the webcam affect the scan completely. It was the cause of misalignment. I have overcome the misalignment problem by pulling the webcam back and away from the calibration board and digitally zoomed in to compensate. But I feel that my scan quality has dropped. I feel that when we digitally zoom we can never focus as sharply as we don't zoom. My misaligned scans were much sharper than my last scans.
-I don't want to zoom.... How can I overcome this problem? I want help specially from the guys who use logitech pro 9000 with Acer K11..If they can share the pictures of how their setup, it would be more helpful...
Can you help me with this issue, at least?(-I must either choose to zoom, or accept that the cam see beyond the dots, or what you suggest!)
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby argo » Mon Nov 11, 2013 3:28 pm

Lunat1c, I guess the problem of using a webcam is mostly because of it's range of view. i mean you have to put it so close to the object to get the right image. and that is why they dont recommend it to useو or some guys modify their webcams to get the image from Further position. so the problem like yours wont happen.

if you can use a tripod for your webcam, try to look at your object from little bit above the recent position. it may solve your problem.

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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby Lunat1c » Sat Nov 16, 2013 7:44 am

A diagonal setup with a raised webcam over the projector seemed to lessen the distortion but couldn't eliminate it. I've got a tripod now, tonite I'll try it.
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby WalterMo » Sat Nov 16, 2013 2:53 pm

From my experience I think the best set-up is if camera and projector are one above the other. Of course it's a bit more complicated to mount as if both devices are side by side.
If they are in one vertical line, both walls of the corner are illuminated in the same way.

Also best is if both lenses, of the projector and of the camera, have about the same focal length. Camera lens ca. 12 mm. So both devices can be mounted at the same distance to the object, the set-up is more compact and they don't interfere with each other.

Walter

Edit: Here are some photos of Mattia's SL set-up. Can you realize a similarity to mine?:
download/file.php?id=7143&mode=view
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SL Setup.jpg
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby Lunat1c » Mon Nov 18, 2013 2:26 pm

WalterMo wrote:Edit: Here are some photos of Mattia's SL set-up. Can you realize a similarity to mine?:
download/file.php?id=7143&mode=view


I was just thinking about the similarity :) before the edit. I dowloaded the 2 photos on my computer to compare them. Because I'm going to copy the aluminum frames. But I will copy yours because I don't have a CCD cam.
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby Lunat1c » Wed Nov 20, 2013 7:19 am

Dear Walter,

Can you give the dimensions of the parts or have you got a drawing at hand?

Hal's and yours are exact as can be seen.

Best regards.
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby WalterMo » Wed Nov 20, 2013 10:34 am

Hi,
Here are the dimensions of my eloxed aluminium rig:

Part A: L= 60 cm, square tube 25 mm x 25 mm, 1.5 mm thick
Part B: L= 52 cm, L-shape 30 mm x 15 mm, 2 mm thick
Part C: L= 40 cm, same as A
Parts D: 2 steel angles 14 cm x 14 cm, 2 mm thick
Part E: Female ¼ inch screw to hold the rig on the tripod, made of brass
Part F: Male ¼ inch screw to hold the camera, made of brass
Part G: Tiltable steel angle for the projector or the laser
Part H: Male ¼ inch screw to hold the projector or a laser scanner

Most of the screws which hold the single aluminium elements are M6 wing screws, easy and fast to open or to clamp. The alumium and steel parts were bought in our local DIY market.
But I couldn't find the ¼ inch screws somewhere. Therefore I had to make them by my lathe.

Walter
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby argo » Wed Nov 20, 2013 11:11 am

Lunat
I think your projector is much heavier than the Acerk11 (the one that Walter and hal use)
you need to be careful and calculate the materials you choose.

in my case i can not use like Walter's frame. i am working on such this setup
IMAG0188.jpg
helping with macdaddyjaz's photo to draw and show the setup


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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby argo » Thu Nov 21, 2013 2:30 pm

HI,

This is what so far i could have manage to make.
Still needs a tripod which can hold minimum of 6kg !!

IMG_0002.JPG


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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby dangre » Thu Nov 21, 2013 5:27 pm

Argo,
I've made a couple different mounts and have learned you really need a SOLID mounting system. ANY vibration or movement will greatly affect your scan accuracy. I would be nervous about your thin, round bar stock. The fan motor in the projector can induce a waveform that will multiply itself in a mount such as yours. But maybe it works just fine. I have attached photos of my mount which I have detailed before but its weak point is the mount for the projector which I need to improve.
Attachments
IMG_0091e.jpg
1/4" bar stock
IMG_0093e.jpg
horizontal and vertical orientation
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Re: DOES THE SHADOW OF THE WEBCAM AFFECT ANYTHING?

Postby argo » Thu Nov 21, 2013 7:01 pm

Hello Dan,

Thank you to share your setup images and info. you have made a really good mount.
Wish i have had a lightweight projector, then could go like yours.
Anyway mine is working just fine(no shaking, nothing to bother).
"I see my picture has not taken well and it appears to show a loosey setup" but it is much much more solid than it shows :wink:
I have used a 2cm thikness teflon(PE) board as a base and both projector and filled aluminum pipe, are well fixed on the board.
and of course there are some spaces between projector and filled pipe.
The only thing is i have made a really heavy package(to compare with others).
Just need time to make a tripod for it.
Wish me luck :wink:

Best Regards and good luck
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