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faq:en_hardware

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Selection of Scan Hardware

Structured Light or Laser?

In general, a Structured Light scanner is the best solution: It is faster, more comfortable, and more flexible because it can scan without calibration panels in the background.
But laser scanning is not bad either. It is preferable in the following cases:

  • The hardware must be as cheap as possible –> Use a red or green laser and a webcam
  • Extremely small objects should be scanned –> Use a blue line laser with adjustable focus and a monochrome CCD camera
  • The scan environment is very bright –> use a strong laser (best green) and a CCD camera

How do I get the best value for money?

We have tested many cameras, lasers, projectors, etc., and also we have received a lot of reports from our forum user community. Then we simply put the most suitable models into our shop.
Based on this experience, we have put together complete scanner packages that contain the best value-for-money hardware components which work perfectly together.

  • The DAVID Starter-Kit allows hand-held laser scanning at an unbeatable price. It contains the best webcam we have found (Logitech), the laser with the best price-performance-ratio, and everything else you need.
  • The DAVID SLS-2 is a complete Structured Light scanner. It contains our favorite camera, a projector with a specially adopted lens, precise calibration panels, a stable tripod and mounting rail, etc.

We are able to offer both packages at a price lower than the sum of their contents.

Which camera should I buy for laser scanning?

Low-cost: Logitech webcam Pro9000 or C615. Use the Pro9000 at 800*600, 15 FPS.
High-quality: We recommend our monochrome CCD cameras. Only if you need to capture color textures, you should choose the color camera. In any case, the camera must support DirectShow.

Which laser should I buy?

Low-cost: Red line laser.
General case, high quality: Green line laser with adjustable focus. Usually 5 mW are sufficient.
Small object, finest surface details: Blue line laser with adjustable focus. Use it with a monochrome camera.

Which camera should I buy for Structured Light scanning?

We (the DAVID team) have tested lots of cameras, trying to find the perfect model for SL scanning. Unfortunately we did not find a satisfying camera, so we developed our own together with our camera hardware supplier. The result is the DAVID-CAM-3.1-M (separately available soon). At this time it's the only camera model that we can recommend 100% for SL scanning.
The DAVID-CAM-3-M is also part of our complete SLS-2 scanner package.

Which projector should I buy?

The projector should fit to the scanned object size. Most projectors can be focused to large screen sizes only, starting at 1 meter. With these projectors you cannot focus on small objects. On the other hand, a micro projector does not have enough power to illuminate a large object (also depends on the environment light).
Our SL projector Acer K132 PLUS (separately available soon) is most flexible and can be focussed to smallest objects (starting at 50 mm “screen size”) to “infinity”. It is also part of our SLS-2 scanner package.

Can I use my camera model xxx?

The camera must be able to send live video feed to the computer. DAVID accesses it over DirectShow, so the camera (or grabber card) must have a DirectShow driver. Try with DAVID (e.g. Free Edition) whether your camera is listed in the “Video Source” menu, and whether you receive a live video.
Also it is important that all automatisms (auto-focus, auto-aperture, auto-exposure) can be switched OFF because DAVID requires constant conditions during scanning.
In general:

  • most webcams will work (but with limited scan quality)
  • most industrial cameras will work fine (given they have DirectShow drivers)
  • photo cameras usually won't work unless they have a “webcam mode” / live video mode
  • DSLR: DAVID supports some Canon EOS models
  • Analog camcorders may work together with a suitable video grabber card, but the image quality may be low
  • Digital camcorders may work together with a suitable video grabber card (e.g. HDMI input), but the video will be transferred with lossy compression, which may create artifacts in the 3D data

Can I use my projector model xxx?

Yes, probably. The projector must be connected to the PC via VGA or HDMI. It must be configured as 2nd screen (“extended desktop”).
The projector should fit to the scanned object size. Most projectors can be focussed to large screen sizes only, starting at 1 meter. With these projectors you cannot focus on small objects. On the other hand, a micro projector does not have enough power to illuminate a large object (also depends on the environment light).
LCD projectors are usually easy to use. Other types (DLP, LED) require long exposure times in the camera (usually 1/60s), so it's best to have a camera with a mechanic lens aperture.

Can I use my laser model xxx?

It must be a line laser. The line must be straight and as thin as possible. Cheap line lasers (like below 10 EUR / 10 US$) often create a very thick or even slightly curved line (like a banana), which will cause imprecise scans.

What is the ideal computer?

Windows 7, 64 bit, modern dual-core or quad-core CPU, >4GB RAM, 3D graphics card from NVIDIA or AMD (middle-price gamer card).

faq/en_hardware.txt · Last modified: 2014/08/25 18:35 by sven