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what about Digital Camera ?

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

what about Digital Camera ?

Postby naxos » Fri Jan 08, 2010 10:07 pm

Hello, i'm new to DAVID scanner...

i've bought the starter kit to get ease to start...

but i also have a sony 180i video camera, and better a canon 5d markII photo camera that can film in fullHD...
more than resolution, this camera is good because i have full control for diaph, exposure, lenses, focus etc...

i also have a compact camera that can film at 210 fps...

So can you tell me what should be the best ?

High res, camera, with witch lens (i can go from 8mm 180° fisheye to 300mm zoom)

fast camera (sfilm first the laser scan, then use the video at low speed to get the laser sloooowly scanning...
this camera at 210 fps is 480 pixels resolution...

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Postby hal » Sat Jan 09, 2010 12:56 am

Hello naxos,

Hey, seems that you have "hard stuff" out there!
If I can, I suggest to:

- use the 210 fps camera and try to record a video of a fast movement (obviously after calibration) of the laser, moved by hand, on the object (you can be the first user that use David with a fast camera and your results could be very interesting);
- use the HD photo camera with projector David Structured Light and take one shot for every projected pattern.

But I think that a good experimentation with the 210 fsp camera can start a good "table of experimentation" for David. And 480 px are enough to get nice results.

I'm very curious to see some results,
Thank you very much,
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Re: what about Digital Camera ?

Postby funtasma » Sun Jan 10, 2010 7:53 pm

I would use the Canon, since in my opinion full control over all your light values is the most important for laser scanning. The good lenses of the DSLR help you to get precise scans and good texture shots. On the other hand you have very low noise in the picture because of the big sensor. That is good as well. I used a Panasonic GF1 for laser scanning. That was better than any video camera. Only disadvantage was, that it wasn't able to send a live picture to the computer, only the ready video. That's why I sold it again. But as far as I know the 5d Mark II is capable to do so.

For small objects up to 40 cm size I would choose a 70-100mm focal length. Usually you have low distortion in the typical portrait range and depth of field is still quite well.

But in principle I would recommend to make experiences with al of them. That's the way to realy learn the advantages and disadvantages of your gear and the software.

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Re: what about Digital Camera ?

Postby eiqi » Sat Jan 29, 2011 6:35 am

Ha, maybe you have the choice, but I suggest you use the Sony digital camera, because I have one, I have used it for a long time, nothing too bad. Like new, and out of the photo shoot very well
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Re: what about Digital Camera ?

Postby JD_Mortal » Wed Feb 23, 2011 7:10 pm

In any camera setup, the most accurate results will come from telephoto lenses, where you physically move the camera further away from the target and zoom-in. This produces a more linear distortion, and less "fish-eye" distortion on all depth-levels.

This works for webcams too. Just remove the cheap plastic lens, and mount the camera in a project box that has a real telephoto lens from a 35mm camera attached to it. Though, this is not for the untechnical people to play with, it will yield much better results. The background and the entire object will all be in focus at one time, as opposed to having one or the other in focus, with a close-up or fish-eye lens.

As for quality of the image. That is actually an insignificant argument. A standard 640x480 with multiple scans will produce the same quality as a 1080p HD camera. Except at a microscopic level, which is limited by how close you can get the CCD or CMOS chip to the object, and still be in focus.

Remember, it is "Multiple scans" that produce high-resolution, not any single scan alone. Get closer, move around, change angles, change focus, change sensor values and stack scans... that is how you get uber-high resolution.

What you need to focus on, (Pun intended), is the compatibility, sensitivity, repeatability, cost, and support of the device you are going to use to capture video. Cameras have about a 2-year support-line, and 2-5 year life-span. Beyond that, you will notice dead-pixels, washed-out images, no software support, and little hardware support. That is where cost is the ultimate driving force. It is better to have 10 new webcams, one new one every year. Than it is to be stuck with a camera that was great ten years ago, and is severely outdated by the current $20 cameras on the shelves at the time. When the only advantage is a few more pixels, which you could have gotten by scanning the object a second time, at a 45-degree angle, or scanning it one inch closer.
DIY laser-line, Hand sweep scanning, Generic driverless webcam (640x480), Cardboard background rig, Adequate results.
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