Imaging coins with movement

xphobe · April 25, 2006 3:48AM

Airplanenut was experimenting with using mov or mpg files to display luster and toning - incidentally, how did that go?

Here's a technique I really like, because the viewer is in control. It's Quicktime VR but could probably be done with Flash. Anyone here done anything like this?

Tungsten token

solid · April 25, 2006 4:31AM

That's very cool! I imagine at some point in the future something like that will be standard
fare for viewing coins before you buy them. I'd like to be able to rock that coin up and down, too.

Ken

messydesk · April 25, 2006 4:51AM

I like this much better than the .mov technique, although keep the coin still and move the light. For each side, you'd need a light positioned every 10 degrees from +/-10 to +/-60 in each the "cranial/caudal" orbit and the "LAO/RAO" orbit, for 144 pictures of each side.

Maybe a movie would be easier, but what fun is that?

airplanenut · April 25, 2006 5:33AM

It would take a long time before this works... the whole point of rotating the coin in the light was that the coin doesn't just look different at different angles in one plane--it needs to rotate in all of 3-space. Plus, this would take much, much more time.

messydesk · April 25, 2006 5:45AM

I never said it was practical.

Simplifying the problem to the 144 pictures per side, moving only the light, it would work just fine, provided you had the patience to take all the pictures. We simplify this by having a robot position the light, and have a computer control both the robot and the camera. Once set up, you could have your 144 pictures in the time it takes to grab a brew from the refrigerator and reheat a piece of pizza.

xphobe · April 25, 2006 6:05AM

I can see Airplanenut's point. To be able to freely rotate it in ANY direction in 3-space would require a LOT of photos. However, being able to rotate only along x, y, and z using 144 photos is a compromise that I think most people would find reasonable.

I wish this were a standard service. Even if the automation hardware is expensive, it would pay for itself quickly.

messydesk · April 25, 2006 7:15AM

Another compromise that could keep the number of pictures low would be to get a 3D map of the surface of the coin so that it could be rotated. If you could image 10 vertices per millimeter, you'd need something like 113000 vertices to have a map of the surface of a silver dollar 38mm in diameter. Then you could feel like you're rotating the coin against a stationary light, and the correct one of the 144 images of the coin taken stationary with the moving light could be mapped onto the 3D surface. So in addition to the robot, now we need a 3D digitizer accurate to the depth of about 1/10000 of an inch. Probably a total of about 15MB of data per side.

mozeppa · April 25, 2006 10:21AM

i just tried it by moving only the light .

17 pictures set up in GIF format 200 by 200 pixels.

680 kb

took 45 minutes to do.

would anyone want me to email them my attempt at this?

mozeppa · April 25, 2006 10:24AM

<< <i>Another compromise that could keep the number of pictures low would be to get a 3D map of the surface of the coin so that it could be rotated. If you could image 10 vertices per millimeter, you'd need something like 113000 vertices to have a map of the surface of a silver dollar 38mm in diameter. Then you could feel like you're rotating the coin against a stationary light, and the correct one of the 144 images of the coin taken stationary with the moving light could be mapped onto the 3D surface. So in addition to the robot, now we need a 3D digitizer accurate to the depth of about 1/10000 of an inch. Probably a total of about 15MB of data per side. >>

or you use this...

numonebuyer · April 25, 2006 10:27AM

I sense a matrix type movie to look at all possible angles.

Very cool.

Get hot on that Jeremy. You do have some free time at MIT, right?

Imaging coins with movement

Comments

Leave a Comment