Hand machined mechanical pencils

Rotary slit scanner (13/01/13)

I recently saw this post on Evil Mad Scientist - an object is rotated on a turntable and a digital camera photographs it from multiple angles. Narrow strips are taken out of the middle of each image and combined into a "scan" of the surface of the object. Obviously this works best for cylindrical objects like mugs.

I'd previously written a little program in VB6 to do slit scan photography using a webcam (using the AVICAP32.DLL library - see here), where it takes a single vertical line of pixels out of the frame and stacks these side-by-side to create an image of anything moving (if this is unclear, do a Google search on slit scan images, you'll get the idea!). Here is a ZIP file containing the source code and executable (remember, you may need the VB6 runtime). It's a bit rough, but should work - click connect, then run.

I realised I could just rig up a turntable, point the webcam at it, and I should get a pretty decent scan of the object's surface. Here's the setup (click for larger):

It worked pretty well! Here's four different objects. The images are pretty weird, but clearly recognisable. The funny scalloped shape at the bottom was a square piece of wood which sat on the turntable - it's distorted due to the slit scanning.


Bottle of acrylic paint

Russian doll

Tin can with animals on it