Hi John,
Another option would be to use WCS (Web Coverage Service), the
lesser-known sibling of WFS and WMS. Where WFS is designed to distribute
Vector data, WCS is designed for Rasters. Up-take has been slower than the
other two, but there are a several open-source tools for serving it (i.e.
GeoServer, MapServer), and one or two for reading it (i.e. GvSIG, GDAL).
See - https://secure.wikimedia.org/wikipedia/en/wiki/Web_Coverage_Service
Jonathan
From: John Callahan <[email protected]>
To: OSGeo Discussions <[email protected]>,
[email protected]
Date: 15/07/2011 19:58
Subject: [Qgis-user] format for raster data distribution, JP2?
Sent by: [email protected]
I'm looking for advice on sharing raster data for download. We distribute
several raster datasets such as DEMs and orthophotography. Sometimes
these are divided into rectangular tiles, sometimes by
geography/boundaries. Most of our audience has some level of GIS or CAD
experience. We also have WMS services but there are many times where
people need the actual data files.
I had been creating JP2 files using JP2ECW compression. Great file size
reduction with very good quality. However, I'm thinking it may be
difficult for people to view these (and more difficult for me to create)
due to the restrictions on the codec distribution. The other JP2 options,
OpenJPEG and libjasper, seems like they also require users to obtain this
codec/driver and install into the software first. Same for the
commercial Kakadu and MrSID. netCDF is great but not widely supported;
IMG are good but not any advantage over TIFs (except for > 4 GB file
sizes)
Since I want to serve the widest possible audience (and not cater only to
our Windows/ArcGIS audience), I'm down to serving TIFs with JPEG
compression at around quality=75, which is what I started with years ago!
Good quality, decent compression, wide support. Is this the best bet?
Is there something else out there I'm overlooking?
- John
***********************************
John Callahan, Research Scientist
Delaware Geological Survey
University of Delaware
URL: http://www.dgs.udel.edu
*******************************
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