[Freegis-list] very large image handling & serving?

[Matt.Wilkie]

Hi All,

What is the current state of open source / free software solutions
for handling and serving very large images?

Please reply to me directly and I will summarize the responses back
to the lists in about a week.

The goal is to serve up ortho-mosaics with the following dimensions 
and size (uncompressed):

RAW MOSAIC
30 metre Standard: 	37,000 x 32,000 pixels = ~ 1.2gig
15 metre Panchromatic:	74,000 x 64,000 pixels = ~ 4.8gig
60 metre Thermal:       18,500 x 16,000 pixels = ~ 296 meg

IMAGE PRODUCTS 
30 metre RGB Composite      =  1.2gig x 3  =  3.6gig
15 metre Enhanced Composite =  3.6gig x 4  = 14.4 gig

The user would display a decimated reference image of the entire mosaic and
draw a selection box to select their area of interest.
This could be via a web or standalone app. Most areas of interest
would probably not be larger than screen size (eg. 1280x1064). 

Clients would require everything from full resolution 1to1 images
for remote sensing analysis to decimated "web-ready" screen shots.

Other notes:

- clients are desktop publishing apps (Word, Excel, Publisher, 
Illustrator, PhotoShop), low end GIS (ArcView, MapInfo), high
end GIS/RS (ArcInfo v7&8, PCI), and web browsers (IE, NS).

- Mutli-segmented intranet, Windows NT 4 domain servers

- hardware of the server is yet determined but is not likely to 
be that good, at least initially (eg. ~1ghz, 768mb ram, IDE RAID)

- the sysadmins are all mostly Win32 based, the *nix expertise is
limited thus any *nix-based solution must be GUI and and should be
WIMP friendly.

- there is a non-trivial amount of ESRI inertia, thus for 
Mapserver to win out over ArcIMS there must be compelling 
arguments with pretty pictures.

- there is a non-trivial amount of Microsoft inertia, thus more
compelling arguments and more pretty pictures.

I have no idea what the actual demand on the server will be, but
potentially a lot -- 595 computers spread over 21 subnets on the
intranet just answered to "net view".

The results of this query are not likely to be implemented by
myself; I will be writing it up a report and passing on 
recommendations.



-matt

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Matt Wilkie * Yukon Renewable Resources GIS
http://renres.gov.yk.ca/pubs/rrgis/
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