Saturday, May 14, 2011

Autostitching an Extra Wide Sky

cloud pano

I thought that I might be able to escape the wind but still get the dramatic skys if I went inland, perhpas to the river. I was only partly right, the wind was just a fraction less, but the blue patch above was opening up and the setting sun was colouring some of the clouds. A perfect moment to capture a big panorama with the sky & clouds as the subject. I didn’t have my tripod handy so I turned my camera to get vertical shoots and zoomed in just enough and then carefully took a set of overlapping photos with approx. 10 degree rotation between each shutter fall. The results was 21 photos in the set (see above). A bonus I was hoping to get was a lovely clear moon. I knew if I could capture all this I would get a great image.

imageThe exposure on the whole set was fine and my hand held horizontal sweep straight enough so I just took everything “as is” into autostitch. The problem I find doing these with the free demo version is I get to a certain size and I get the very terse warning out of memory and that’s it, Autostitch wont play anymore. I think this boundary is the physical memory on your machine rather than anything hardcoded. So I just have to ease off a bit, in this case I found 16,400 pixel wide would work (and take 64 passes and 20minutes to run) which gives me an image I can safely print at around 54” (ie 16,400/300 because the print is likely to be 300 dpi) or around 140cm wide. Big enough! I could go bigger with microsoft’s ICE, imagebut if I do that will be a separate post.

The only other step was to crop out the ragged edges, using picasa and the tiniest of straightening. I still need to find a nice way to find all the detail of these extra wide images, without having to resort to photosynth (that is easier using ICE).pano-1

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