Re: Gigapixel, handheld...
Thomas Bredenfeld 2009-Dec-11 12:59:08
respect! absolutely awesome work, erik!
i felt free to write a little blog entry about it (in german):
Erik Krause schrieb:
> A multi viewpoint, three different focal length, handheld spherical
> I didn't plan to make this one. It was just an experiment, from
> multiple points of view (literally ;-)
> Me and my family climbed the Sidelhorn near Grimsel pass in
> Switzerland this summer (the kids had much fun searching for quartz
> crystals) and I had my usual camera rucksack with me - no pano head,
> no tripod. From the summit there was a magnificent view all around,
> with two of the most impressive mountains over 4000m in the Bernese
> range (Finsteraarhorn and Lauteraarhorn), the Matterhorn far in the
> dust and the Furka Pass, Uri granite mountains and the Rhone glacier
> in the east. And a view down in the upper Rhone valley (called Goms),
> to the Aare glaciers and lakes.
> So I took a two row 360° panorama at 50mm from four different
> viewpoints around the summmit in order to avoid having the mandatory
> cross on the summit in the image and to view down in all adjacent
> valleys. I thought of something similar to those "from the tower
> without the tower" panos.
> Because the sky was so nice I took an additional 360° cylindrical
> from the sky just above the mountains at 24mm focal length. I planned
> to make a high res cylindrical of the 50mm and 24mm images.
> And because it was so nice I took an additional complete spherical
> with the 16mm fisheye, bracketed -2, 0, +2...
> Month later when I was at my parents during autumn holidays I had
> nothing to do, but I had an old 2.4GHz 512MB notebook and the
> external disk with all the images from summer with me. So I set up
> some PTGui projects. It turned out that one exposure step from the
> fisheye was the same as the exposure I took the rectilinear images,
> and so I got curious whether it was possible to stitch the fisheye
> and the rectilinear images together and how far I would get with this
> tiny machine.
> For ease of use I converted all images from raw to jpeg but with full
> resolution (20MP) and maximum dynamic range. To my suprise it was
> possible to load all 82 images into PTGui and align them. After some
> playing with blend priority the preview in pano editor looked pretty
> promising. I didn't dare to actually stitch, since PTGui reported
> that 118 GB temp space where needed and the internal hard disk is 20
> GB only. But now I wanted to make it, on my old machine at home or on
> a new one which I wanted to buy anyway.
> When Max Lyons published the first gigapixel in 2003 my computer at
> home was already three years old and I thought I would never ever
> stitch a gigapixel on this machine. Max reported two days of
> optimizing. Well, PTGui took some minutes only to optimize the
> project on the poor notebook and not far longer on my computer at
> home. It was a challenge for my old Athlon 1.4 GHz, 1.5 GB - if it
> failed, there would be a new computer in several weeks...
> I optimized all images together. Actually I had to set several
> control points manually between the different focal lengths, but
> after some iterations it optimized well. Then I split the project in
> three, one for each focal length. I stitched the two lower resolution
> ones to their recommended maximum size, and the high resolution one
> consisting of 62 images to 46,000x23,000 pixel (maximum would have
> been 52,000x26,000).
> Stitching was ready after 14 hours (I was prepared to cancel the job
> after 36 hours) and delivered a 10 GB .psb file, containing the
> blended panorama and all individual warped images, which I needed to
> retouch huge parallax errors because of multiple viewpoints. So next
> came photoshop - would it open the file? Yes, it would.
> It took about 1 hour to load, but working the masks with the brush
> was relatively fast. Flatting the image took more than an hour as
> well as saving the edited .psb.
> When all three panoramas where more or less ok, I loaded them all in
> PTGui again in order to blow the lower resolution ones up and take
> advantage of blend priority and the PTGui blender. Processing took
> about 12 hours again. Result was 8GB large (3 layers + blended) and
> took about the same times to open and process in photoshop.
> During retouch work I discovered, that PTGui blender did a poor job
> on slight parallax errors in the high res version (structure doubling
> along the seam lines, which I know from ancient PTStitcher feather
> blending). So I decided to give enblend a chance. For this purpose I
> merged non-overlapping images into single layers. 62 layers where
> reduced to 7 with the hope to speed up enblend. The -a switch does
> the same and usually speeds up enblend a lot. My assumption was that
> pre-assembling images would speed it up even more.
> Enblend 3.2 crashed with an out of memory error, which is possibly
> the documented memory leak in this version. Enblend 3.0 succeeded
> after one night of processing and delivered a nice blended result
> almost without the double structures. I replaced the respective layer
> with the enblend result and could focus on the blending between the
> different resolutions now.
> After some adaptive contrast enhancements (large radius USM took
> about 2 hours to complete and 1 hour "prepare to filter" on each
> layer) and hour long saving I had no chance to view the full
> resolution version locally on my computer. DevalVR refused with out
> of memory. I had to scale down by half.
> Then I started FTP upload to 360cities, which took 7 hours. Next
> morning I had the first view and a shock: There was I white stripe in
> the pano. No, it was not 360cities image processing, it was me.
> Searching back through the different versions was pretty tedious -
> any one took ages to load, but finally I found a stripe free version.
> The cause for the stripe must have been a layer copy in photoshop
> with shift key released too soon.
> In the 3 hours I had each day there was hardly time to load the .psb,
> do one operation and save again. So it took another week until I had
> re-done the necessary editing and fixed some more stitching errors.
> Ah, ok, the URL, finally. Have fun:
> Who ever finds a stitching error can keep it for better days ;-)
> There surely are a lot more than I fixed. I'm not very satisfied with
> the transition between high and low resolution in some places while
> in other places it looks quite ok - but I hope no casual user will
> look down hires on boring stones...
> best regards -- Erik Krause http://www.erik-krause.de
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