4 May 00:43 2015
Shooting a subject from all directions, similar to cartography
piccolbo <piccolbo <at> gmail.com>
2015-05-03 22:43:54 GMT
2015-05-03 22:43:54 GMT
I was thinking recently about all the different techniques that are made possible or more powerful by combining multiple images (panorama, hdr, focus stacking, etc) and it seemed to me one had not been tried yet: shoot the same subject from many directions. Sounds like the dual of panorama photography, whereby one shoots in many different directions from one position. Kind of swapping the photographer and the subject. Like most ideas I come up with, it's not new. In fact it's about the same, geometrically, that's done when mapping the globe to a surface as in cartography. Not even new in Hugin circles, see https://groups.google.com/forum/#!searchin/hugin-ptx/globe/hugin-ptx/kju8CPAgOOY/TUfB8AAHqJwJ. Despite doing my best to follow the advice in that thread and plenty of experience with panorama photography in Hugin, I end up with results like this:
This is my process: The object, a fruit bowl, is on a stool with a dark background, camera on a tripod. Shot 17 pics at approximately regular angular intervals by rotating the subject, not moving the camera. The distance remains consistent this way. Light is soft, a little stronger from the left. Adjusted curves in Aperture for all pics, imported in Hugin. Use cpfind to find control points with option --linearmatch to reduce spurious finds. For most pairs, control points are on the bowl, for a few on the background and support. Fix manually. Add horizontal line to each frame to avoid snake like stitch. Optimize positions first, then release a few parameters at a time to see what happen. Image above is obtained by optimizing everything. a, c, d,e, g are nontheless 0, TrX, TrY, TrZ almost 0. Plane yaw and pitch are mostly low, with a couple of outlier images. Worst distance is 25, most < 4. I am aware that parallax changes will make it challenging to map the fruit in a continuous way. I am just focusing on the bowl and no cps are on the actual fruit. Does anyone understand what is going on, let alone how to fix it? Thanks
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