Please take me back to first principles so I can better follow this thread (it's of interest to me, but let me get a cutting head going first :-).
The scanning device is mounted on the head and then the head is "driven" by software through a xy grid over the object?

Surely if we "drive" the head, then we know where it is, so can reconstruct the height of the head from the object (conversely the Z height of the surface at any xy point)?

More complex: If there is much z variation in the scanned object then this is "eyeballed" and the grid modified to roughly follow xyz needed to keep the scanner within its required distance from the object, but high enough so the head does not hit the object?

Red, you have it exactly right. The reading head stays at a fixed height, on the y-car, above the bottom of the gantry, which means it cannot crash into the object.

One of those scanner to hook up onto the gantry. 20110-00 South African ? money
http://www.cncsolutions.co.za/laser%20scanner.html

ZAR ( SA curency) to USD $ = +/- 0.145
So = +/- 2910 us$
Robert ;)

Hi,
I have not built the Mechmate yet but i can offer free laser Scanning services to all of the forum members of this great community...
www.free3dscans.blogspot.com
Regards

Thanks Khalid!

I have one question, are you using David scanner? Your results are fantastic!

I've seen Khalid's posts on the ArtCAM and CNCzone forums, and he does do good work. He uses the David scanner.

I wish I could find more information on Streamline Automation's products, including their scanner.

Here is on Streamline automation
http://3dcutting.com/

Not sure this would have the resolution you might want but the x box kinect is being used as a 3d scanner. There's lots of info on the Web. I picked one up used for $30 to use - but just have too many other things going on right now to have played with it and report any results...

I have used a number of different scan methods for use just as Streamline does.
Actually, modified #5 do cut large statues based on their large machine with removable table and 4th axis.

Streamlines "frog" based series of things uses technology similar to the David principle with a custom interface. Any IR / 2 head scanning system would work for what I see in this discussion thread.

Personally, the hand held david version has always worked well for me for small/med size objects that did not have really super high detail.

2 cents.
Sean