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2008.08.19 16:05 "Re: [Tiff] Regarding DICONDE and its Specification", by Bob Friesenhahn
- 2008.08.20 12:37 "Re: [Tiff] Regarding DICONDE and its Specification", by Harsha
- 2008.08.20 14:03 "Re: [Tiff] Regarding DICONDE and its Specification", by Gene Amtower
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2008.08.22 15:21 "Re: [Tiff] creating sparse files......", by Toby Thain
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2008.08.22 08:56 "[Tiff] creating sparse files......", by Rogier Wolff
- 2008.08.22 13:11 "Re: [Tiff] creating sparse files......", by Toby Thain
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2008.08.22 14:44 "Re: [Tiff] creating sparse files......", by Bob Friesenhahn
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2008.08.22 16:27 "Re: [Tiff] creating sparse files......", by Rogier Wolff
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2008.08.22 16:40 "Re: [Tiff] creating sparse files......", by Bob Friesenhahn
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2008.08.22 16:52 "Re: [Tiff] creating sparse files......", by Rogier Wolff
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2008.08.22 18:11 "Re: [Tiff] creating sparse files......", by Bob Friesenhahn
- 2008.08.22 20:02 "Re: [Tiff] creating sparse files......", by Phillip Crews
- 2008.08.23 15:08 "Re: [Tiff] creating sparse files......", by Rogier Wolff
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2008.08.22 18:11 "Re: [Tiff] creating sparse files......", by Bob Friesenhahn
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2008.08.22 16:52 "Re: [Tiff] creating sparse files......", by Rogier Wolff
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2008.08.22 16:40 "Re: [Tiff] creating sparse files......", by Bob Friesenhahn
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2008.08.22 16:27 "Re: [Tiff] creating sparse files......", by Rogier Wolff
- 2008.08.25 06:28 "Re: [Tiff] creating sparse files......", by Andrey Kiselev
- 2008.08.25 09:37 "Re: [Tiff] creating sparse files......", by John
- 2008.08.26 13:14 "Re: [Tiff] creating sparse files......", by Edward Lam
- 2008.08.23 18:49 "Re: [Tiff] creating sparse files......", by Rogier Wolff
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2008.08.22 08:56 "[Tiff] creating sparse files......", by Rogier Wolff
2008.08.22 15:21 "Re: [Tiff] creating sparse files......", by Toby Thain
On 22-Aug-08, at 11:44 AM, Bob Friesenhahn wrote:
> On Fri, 22 Aug 2008, Rogier Wolff wrote:
>>
>> I'm stitching kind of large panoramas. This results in big
>> intermediate files. On my last run, which took overnight to stitch, >> I thought 42 Gb of free disk space would be enough. Wrong!
>>
>> I got over thrity files of over 1.2Gbytes, filling up the disk.
>>
>> It turns out that most of the files contain lots of zeroes. On Unix >> this can be stored effciently by not issueing a "write" with a buffer
>> full of zeroes, but by seeking over the area. The operating system >> will act as if the area was filled with zeroes.
>
> This is an interesting issue. While holey files seem like a
> panacea, there can be some drawbacks. They are best for files
> which are written just once (like core files) and not so good for > files which are expected to be updated in place. For files which
> are updated in place, the updated hole is quite likely to increase > disk fragmentation since now it takes more space and the space will
> need to be from some other place on disk. Fragmentation behavior > is quite filesystem dependent.
>
> It is worth considering enabling filesystem compression, or using > whole-file compression. Perhaps even just enabling normal TIFF
> compression (e.g. LZW) is sufficient to eliminate the long spans of > zeros.
Agreed, LZW (or even RLE) will be effective here.
--Toby
Bob
======================================
Bob Friesenhahn
> bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/
> bfriesen/