Timeline for How can I improve stitching of nadir and zenith shots in 360º hemispheric panos?
Current License: CC BY-SA 2.5
9 events
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| Sep 24, 2010 at 2:51 | history | edited | mmr | CC BY-SA 2.5 |
addressed concerns specifically about the zenith and nadir.
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| Sep 24, 2010 at 1:43 | comment | added | mmr | @Reid-- Take a look at the commentary that follows, about mercator projections and sampling. Long and the short: take more photos, more than you think you need. | |
| Sep 24, 2010 at 1:32 | comment | added | Reid | I don't see how this answer addresses the zenith and nadir, which are the key special cases being asked about? | |
| Sep 23, 2010 at 17:57 | comment | added | mmr | Here's an analogy that I hope works. Imagine a 3' diameter beach ball. Say you take a bunch of 8"x10" images from inside the beach ball; the corners of those images will be more distorted than taking, say, 4"x6" images. If you overlap your 4"x6" shots,then the final mapping back should be very decent, much better than the same number of images shot at 8"x10", because there's less corner distortion in your original images. Did I make sense there? | |
| Sep 23, 2010 at 17:54 | comment | added | mmr | If you're remapping the final product onto a sphere, then I'd be concerned more with sampling. As you take the photos, you're projecting the world onto a 2D plane. Then when you remap back to a sphere, you're curving those photos to undo the projection of the original photo. If you shoot wide, then the final image will be very distorted just as a propagation of error. If you shoot zoomed in, you'll take loads of photos, but then you'll have less errors. | |
| Sep 23, 2010 at 17:38 | comment | added | Rob Clement | The distortion doesn't bother me as my end product is a virtual globe. In other words I hope it does distort, as much as it needs to. But it needs to distort correctly so when I past the image inside a virtual globe it will look natural. | |
| Sep 23, 2010 at 14:55 | comment | added | mmr | @Rob-- if you imagine that the final image will be shaped like an H (because of the mercatur projection mathematics), then you need to take extra photos in the center of the H to account for this distortion. If you take a true hemispheric pano (ie, a complete half of the tennis ball, not just a stripe around the equator), just like how Greenland is distorted, you will distort the top and the bottom of the image. There's not much to be done about that, except to try to get some distance and to go more for the equator than the true hemisphere. At least, that's how I understand the math. | |
| Sep 23, 2010 at 5:53 | comment | added | Rob Clement | Good point on the polarizer, didn't think about that. And I must say for hand-held that is a beautiful image. Do you have any suggestions on capturing the zenith and nadir points of the pano though? This is what I'm after. | |
| Sep 23, 2010 at 1:46 | history | answered | mmr | CC BY-SA 2.5 |