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| Subject: | RE: GISList: Working with large rasters ~100Gb and GIS |
| Date: |
03/17/2003 10:17:19 AM |
| From: |
Cristoforo Abbattista |
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Hi list
what I can say you is that in our developments we manage such files
through Image Web Server (by Earth Resource Mapping) and I had
never found
Internet applications which manage these huge files in other ways
For example in the site
http://www.cartografia.regione.lombardia.it/cartanet
we deliver to web clients an orthophoto whose not compressed size is
200GB, while compressed in ECW format is 12GB
I think that you should know that there are many free plug-in
(http://www.ermapper.com/download_new/download.aspx#1
or
http://www.planetek.it/prodotti_eng.asp)
to manage ecw files in your typical applications like Photoshop, MS
Word
or other Regards
Ing. Cristoforo ABBATTISTA - WebGIS Project Manager
Planetek Italia s.r.l.
Via Massaua, 12 I-70123 Bari
Tel.: +39 080 5343750 - Fax: +39 080 5340280
cristoforo.abbattista@planetek.it
Web: http://www.planetek.it
> Dear Uffe and others,
>
> It greatly depends on the type of data you are loading. ArcSDE
> supports a number of compression techniques, and these compression
> techniques may greatly reduce the amount of data stored. However, the
> compression techniques can be relatively to very ineffective compared
> to uncompressed data, depending on the type of data. Scanned maps and
> vector data generated images can greatly benefit from a compression
> type like LZ77. Areal photographs etc very often increase in size
> using LZ77, compared to uncompressed. ArcSDE also supports a JPEG
> lossy compression scheme, and that will compress areal photographs
> quite well. The drwback of that approach is that JPEG is lossy, and it
> is much more lossy than MrSID and ECW are.
>
> So, there are a number of factors that greatly influence the resulting
> size in the database. these factors are: - the compression in the
> original file. TIFF input files can be uncompressed, but they can also
> be stored as Packbits compressed, LZW compressed, Fax Group 3 and 4
> compressed, even JPEG compression can be used within a TIFF file. -
> The type of data in the original files. vector generated images and
> scanned maps are always easier to compress than areal photographs are,
> if you want to keep the quality comparable to the original data. - the
> compression scheme you choose in the database. - the type of database.
> Though I'm not sure about this, I get the impression that Oracle tends
> to be a bit more compact than for instance SQLserver. However, I may
> be mistaken there.
>
> The discussion is indeed very interesting. Storing and providing to an
> organization 100GB of areal photographs is quite uncommon (yet), there
> is no silver bullet that will do the overall trick. I am curious to
> know the outcome.
>
> All the best,
>
> Dirk Voets
> Support Engineer
> ESRI Nederland B.V.
> Tel : 010 - 217 07 50
> Email : GISsupport@esrinl.com
> Internet : http://www.esrinl.com
>
> Call aanmelden via Internet:
> http://www.esrinl.com/ondersteuning/callNL.asp, FAQ's op:
> http://www.esrinl.com/ondersteuning/vragen.asp
>
>
> -----Original Message-----
> From: Uffe Kousgaard [mailto:uffe@routeware.dk]
> Sent: Friday, March 07, 2003 3:50 PM
> To: GIS Community
> Subject: Re: GISList: Working with large rasters ~100Gb and GIS
>
>
> From: "Voets, D." <D.Voets@esrinl.com>
>
> > ArcSDE will basically be able to load all that data, but it will put
> > tremendous constraints on the database you use. This may not be the
> easiest
> > way to handle your data. There aren't too many databases and servers
> that
> > can handle this. Your data would probably double or triple, because
> > of indexes and storage procedures in the database.
>
> I have loaded 550 Mb of GeoTIFF files (PackBits compressed) into
> ArcSDE 8.2 on Oracle 8.1.7. That resulted in a 110 Mb increase in used
> space on the server, so I can't really recognize your double/triple?
> This was including pyramids and using LZ77 compression (loss-less).
>
> Since I'm about to load a total of 30 Gb of TIFF files, I find this
> discussion very interesting.
>
> Regards
> Uffe Kousgaard
>
>
>
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