Re: [CAD_CAM_EDM_DRO] Re: poor mans digitizing gizmo

>
>
>Actually, you only need one camera. Take the picture, turn the item (or
>move the camera) and take another picture. The more pictures the
>better. Then you use photogrammetry software to create your 3D model.
>Uzr3d for the Mac and PC is one such package.
>http://www.macroenter.com/uzr3d.html
>

True -- the limitation for portraits (their application) is that the
images need to be taken at the same time, since people tend to move.
They need 2, 3, 4, 5 or more portraits, from different angles, all of
which are otherwise identical.

But, enough of this. I had another thought. I have a Logitech optical
trackball -- the one with the spotted red marble ball. Think ball joints...

By tying together some optical mice (now down to a few dollars each at
Fry's and Micro Center stores) to the articulated joints of an arm, you
could track the angular movements of an arm with relative ease. Since
the length of the arm segments is fixed, use a little trigonometry, and
you've got 3D location information. This technique should give quite a
high resolution, too...the M$ mice supposedly take up to 6000 images per
second, and the cheaper ones take around 1600 images per second. In any
case, with an appropriate surface for tracking (which can be almost
anything with an optical mouse) you could get several thousand dots per
inch, interpreted. Should be more than adequate for inputting a shape,
especially with a large ball at each joint, for higher resolution.

Of course, backlash in the system would probalby spoil that wonderful
precision, but it'd be a cheap and relatively simple approach to the
problem...not to mention "easily" home buildable.

-- Chuck Knight