Landon, Rather than sput off about something theoretical, I'll relate our use of MRSID deliverables.
This is our Typical publishing process for MRSID format data that we receive, which happens fairly regularly. Our use case in this instance is for visual inspection of aerial photography. * First we extract JPG tile pyramids from the MrSID format into MapServer ready tile layers doubling/halving the resolution of the output for each level of tiles along with generating WORLD files for each tile. (we actually have a static grid that we use for tiling that makes this a one time process, since the WORLD files are reusable across data sets.) * Then, index the tiles for each level for Mapserver's use We start at Level "0" (L0 = 6" resolution) and increase by doubling resolution until we have a single tile at the City view level, ~L7. * Mapserver is setup with a multi-level display with cutoffs for each tiled layer at the appropriate scales. * This approach guarantees only four tiles at most (as long as the client viewer pixel width isn't bigger than the tile pixel size of each tile) are ever retrieved by MapServer to build a composite output image. The first three steps could be automated into a package that ran automatically for example from most MRSID deliverables. Another use case might be DEM analysis, which might require converting into other formats as well as the data originating in some other format besides MRSID. Still another use case might be spectral separation and handling the consequent analysis tasks. Anyway, the list goes on and on I sppose. bobb >>> "Landon Blake" <lbl...@ksninc.com> wrote: Bob, What did you have in mind when you said “pre-processing”. Landon Office Phone Number: (209) 946-0268 Cell Phone Number: (209) 992-0658 From: discuss-boun...@lists.osgeo.org [mailto:discuss-boun...@lists.osgeo.org] On Behalf Of Bob Basques Sent: Monday, August 24, 2009 9:21 AM To: OSGeo Discussions Subject: RE: [OSGeo-Discuss] Open File Formats andProprietaryAlgorithms Landon, Just had another thought . . . What about setting up a (openSource) tool set specifically for handling Raster images for pre-processing purposes. Might even be something that publishers could re-distribute with their datasets, as in this processor stack works with our data. Just thinking on the run here, no detail (or ramifications though through [at all :c) ]) bobb >>> "Bob Basques" <bob.basq...@ci.stpaul.mn.us> wrote: Landon, >It would be interesting to come up with a standard structure on a computer file system that could be used to accessed tiled raster data, if this hasn’t been done already. One the file system structure was defined, it would be fairly easy to write open source software that accessed this structure and provided individual tiles as a service to desktop GIS applications. Hmm, interesting angle, to expand on your idea a bit more, what about a processing suite (or set of suites) that process data for different types of uses, visual display, DEM analysis, etc. Each "processor" stack would/could have it's own rules associated with data resolution vs files sizes, etc. bobb >>> "Landon Blake" <lbl...@ksninc.com> wrote: Bobb wrote: “Here's my reasoning, we're never (ever?) going to hit the top end on how big files ever get, resolution just keeps going up and up, so there is always going to be some upper limit that will need to be breached somehow. Working out a proper method for segregating the data up front (dare I say it), as some sort of standard (which can be adjusted as time passes) will make everything work nicely, then all will work with available tools when they are available, if tools to handle larger datasets become available, and the communityI agree with some of the points you are making in your argument Bobb. There is certainly a practical limit to how much you data you should put in a single file. That is why we have lumber cut to 8 foot lengths. You don’t need a flatbed semi to carry it to your house. :] When you refer to a standard for splitting data up front, what do you mean? It would be interesting to come up with a standard structure on a computer file system that could be used to accessed tiled raster data, if this hasn’t been done already. One the file system structure was defined, it would be fairly easy to write open source software that accessed this structure and provided individual tiles as a service to desktop GIS applications. Landon From: discuss-boun...@lists.osgeo.org [mailto:discuss-boun...@lists.osgeo.org] On Behalf Of Bob Basques Sent: Monday, August 24, 2009 7:33 AM To: OSGeo Discussions Subject: RE: [OSGeo-Discuss] Open File Formats and ProprietaryAlgorithms All, Ok, I'm probably going to get someone irritated, but here goes . . Why not approach this from the other end of the spectrum and work at making the original files smaller. Work with the providers to make the images smaller in the first place, or at least come up with a maximum practical size to work with, I mean if this is the only (or biggest reason) for implementing JP2, then getting folks to make the smaller deliverables seems like a better long term approach. Here's my reasoning, we're never (ever?) going to hit the top end on how big files ever get, resolution just keeps going up and up, so there is always going to be some upper limit that will need to be breached somehow. Working out a proper method for segregating the data up front (dare I say it), as some sort of standard (which can be adjusted as time passes) will make everything work nicely, then all will work with available tools when they are available, if tools to handle larger datasets become available, and the community feels there is a reason/need that these new larger files need to be handled, then they get to change the standard. bobb >>> "Fawcett, David" <david.fawc...@state.mn.us> wrote: I realize that there are likely not a large number of people who have the expertise and experience to write this kind of code. Is this a project that should be shopped around for funding? Google Summer of Code? A grant from our ~benevolent overlord Google? Some other foundation or org interested in open data formats? David. -----Original Message----- From: discuss-boun...@lists.osgeo.org [mailto:discuss-boun...@lists.osgeo.org] On Behalf Of Michael P. Gerlek Sent: Thursday, August 20, 2009 4:36 PM To: OSGeo Discussions Subject: RE: [OSGeo-Discuss] Open File Formats and Proprietary Algorithms <snip> > Do you know why there hasn't been a broader adoption of JP2? Not through lack of trying on my part :-) I think the two biggest reasons are: (1) The algorithms for handling large images in memory really are rocket science, and no one in the FOSS community has gotten the "itch" sufficiently bad enough to go and do the work needed inside the existing open source packages. Hopefully someday someone will. _______________________________________________ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss _______________________________________________ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss Warning: Information provided via electronic media is not guaranteedprohibited. 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