[OSGeo-Discuss] fastest option of serving huge imagery on web map on the fly

karsten vennemann karsten at terragis.net
Thu May 20 12:37:11 PDT 2010


Hi All,
 
I am seeking some advice/ alternative ideas about the following project I am working on...
I have been tasked with researching the best and fastest options serving huge raster datasets on a web map using OpenLayers o the fly (using all Open Source software). We want to serve the US NAIP Aerials in 1m resolution (which are a total of about 4.7 TB of MrSid/Jp2 data) on a interactive  web map as an optional map background. The are using MapServer to serve our other  (vector) data such as roads, rivers etc as WMS  to overlay onto this. Of course there are many ways to go about this but one of the things we determined early on is that MapServer is too slow to serve compressed imagery such as the native MrSid Jp2 imagery on the fly for our needs. Thus, one option would be to spare MapServer from having to decompress the images. We can then also avoid having to convert them to tiff and adding overviews (using gdaladdo for example). This would also "blow up" the total data volume to something about 60 TB ...
Thus, we are in the process of researching options on how to serve the compressed data as fast as possible "on the fly" and without the need for caching them on disk (that means no TileCache nor GeoWebCache should be used because that also would involve having to set up huge storage spaces ...
One option I came about was using IIpimage server and this would then involve converting the MrSid all to Jp2 format. One advantage is that OpenLayers 2.9 already has natively the Zoomify layer support so that we can easily add the images coming out of IIPImage Server Zoomify + JPEG2000 server http://help.oldmapsonline.org/jpeg2000/
I also found that another option is the Djatoka Jpeg 2000 Image Server http://sourceforge.net/apps/mediawiki/djatoka/index.php?title=Main_Page and the J2K Tiler Renderer: http://dltj.org/article/introducing-j2ktilerenderer/. 
None of the above seem to enable output as WMS (correct me if I'm wrong). One draw back is that all of those above are using the Kakadu library which is great but not free for commercial use.
I also wanted to research how the use of this new proxy server http://mapproxy.org/ could improve our speed in combination with e.g. IIP Image server... 
 
Anybody has experiences with any of the above or comments ?
Any input what you think would be the fastest option to serve the compressed US NAIP onto a web map on the fly (without caching tiles on disk) ?
 
Cheers
Karsten
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