I'm having too much fun with this not to post something about my new technique using focus-stacking on ancients.
Since many ancients have significant relief, a single small-aperture shot may not capture all the details. So I've turned to focus-stacking software to build a final image that gets all the possible detail.
Here's an example I just did--the owl side on my Athens Tetradrachm. I wanted to capture an accurate tonal range, as well as illuminate the rims so I can best render the coin in 3D. So I used two diffuse lights from opposite directions. The picture below is a stacked composite of 56 individual shots. That's sure a lot of steps; the fine focus increments were necessary to capture an accurate depth map for 3D.
From this stacked composite, Helicon Focus generates a depth map, shown below. The steps may seem almost imperceptible, but there's a lot of depth information captured here, later to be used in 3D.
From this depth information, Helicon will generate simulated 3D models at many angles. You can adjust the relief modifier to best represent the coin's depth. Here, I've chose a value to give a dramatic view of the coin at several angles:
click to see the details!
I'm pretty happy with the results, although the rims could be thicker. The program could not approximate the rims because the camera did not capture all this detail from a shooting angle perpendicular to the coin.
Finally, the program will generate a 3D animation of the coin being turned in space. I find this the most informative and fun--motion in 3D may be the best way to study the coins depth. The snapshot below doesn't reflect video quality--click HD to see the best detail; full-screen here.
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The ragged rectangle behind the coin is how the program renders a dark gray background. This might be fixed by deleting the bkg before stacking--but it would be significant work.
Thanks! The software is Helicon Focus I did this using the trial-period download--it includes the 3D viewer. Now that I've tried both, I prefer this program over Zerene Stacker.
In case you're curious about removing that ugly background to get a cleaner video, here's what happens when you crop the bkg out of the source files. Since each picture is at a slightly different size due to focus, the software isn't able to render a clean edge--the result sure looks messy! It's easy to clean up individual pictures like I did above, but you would have to edit the video in post-production, which could be very time consuming.
Quote: Would like to see your avatar picture side by side with this one at the same size for comparison.
Unfortunately, my avatar isn't a coin I own--that's definitely a nicer example!
Badger_Mint--it's one angle, multiple shots. The "layers" seen in the depth map give you and idea of the number of shots. From there, the program generates simulated relief which can be displayed at many angles. To a point--the rim thickness isn't well rendered. I should add...this particular coin, with some strongly defined/raised design elements, is probably the perfect coin for this demo. Next step--I will do the same for the side with Athena.
Quote: I wonder if one day we will have a 3D setting on our common cameras?
With 3D movies and home 3D HD TV screens out there, I'm suspect it will eventually get popular for video cameras. Not sure how you would adapt a still camera like mine, unless you pair up 2 different shots and view them on a 3D screen.
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That's sure a lot of steps; the fine focus increments were necessary to capture an accurate depth map for 3D. 
Posted 12/08/2014 3:39 pm
