Starter Help : Laser and camera

Which camera, which laser? - that´s the one and first question of a DAVID-starter.

Keep in mind that the idea behind DAVID is to offer a “Definitely Affordable Vision Device”.

So before starting to spend money think about the fact that it is always a good idea to spend as little money as possible to do the first steps. If you allready own a webcam or linelase, whatever the quality: Try it! you will not get perfect scans with this hardware but keep in mind that even with perfect hardware your first scans will not be perfect.

By practicing with your available hardware you will get a feeling for DAVID and you will be proud when you get your first results. Moreover the feeling for DAVID that you get by practicing will help you make decisions on the next piece of hardware to buy or build.

So the right choice depends on your aims.

What do you want to scan?
Which accuracy of the resulting mesh is necessary?
What means “affordable” for you?

This is the sort of image you are looking for during a scan.

Camera

Generally EVERY camera, that is able to record or stream a video can be used, for DAVID owns two gateways to get the video of the laserline on the object:

DAVID can grab the frames of a stored AVI-video with DAVID Video Grabber; So, as long as you´re able to store a video of the cam on your PC, you will be able to use the cam for DAVID. Even an old analog cam may be used, if you record its video on your PC using a TV- or grabber-card.
DAVID can catch the frames from a PC-camera (e.g. “webcam”) in live-mode. The one and only requirement is, that the cam has to support WDM Video-Capture-Driver for Windows.

Webcams

Webcams, are mass produced, offer good, but shurely limited quality for little money. There are some aspects you should keep in mind buying one for DAVID:

General aspects:

In most cases, DAVID works in lowlight conditions to get a clear contrasted laserline. So the cam should be able to handle this. You need high light sensitivity and as little noise as possible.
Most webcams are not produced to do their job in such extreme lightconditions, their automatics are often overstrained. You should have the option to switch them off.(Autofocus, shutter- and gain automatics…)
If you have to switch off the automatics, you have to have the option to set focus, exposure/shutter time and sensitivity/iris by hand.
In most cases glass optics generate less lens distortions.

Aspects for special purposes:

Resolution: Higher resolution of the cam´s picture gives more accuracy and details (if your laser line is fine enough), but your framerate will fall. So if your object tends to move (like a vivid object) higher resolutions are limited.
Framerate: The higher the framerate, the lower is the possible scanning time. But high framerates are only possible at lower resolutions. You will never get the maximum framerate of a cam at its maximum resolution. So if you plan to scan inanimate, unmoving objects the framerate is less important.

Cams successfully used by DAVID-Users

( Note: This list is only a sample of used cams in alphabetical order, no ranking!. Please add your cam and your experiences! Use headline H5 to add a new one. The framerates depend also on the used PC-hardware! )