I like the idea. It sounds like a pretty good fit for this situation. I also like listing in capabilities and to the user since it makes it explicit that the crs is more or less uninitialized and was the servers final guess. +1.
How will/should this be introduced? Should we introduce a system property to engage it for the time being to give it a bit of testing before making it the default behaviour? Or perhaps a flag to turn it off in the event it leads to some unforseen issue? On Sun, Jan 9, 2011 at 4:19 AM, Andrea Aime <andrea.a...@geo-solutions.it>wrote: > Hi, > I'd like to hear what people think about the idea of adding a new > custom EPSG code, EPSG:0, to GeoServer, to be used when no EPSG code can be > guessed from the data source (or when it's just plain missing). > EPSG:0 would map to DefaultEngineeringCRS.GENERIC_2D, which is designed to > be > a lenient wildcard CRS, from the javadoc: > > ---------------- > > A two-dimensional wildcard coordinate system with x, y axis in metres. > At the difference of CARTESIAN_2D, this coordinate system is treated > specially by the > default coordinate operation factory with loose transformation rules: > if no transformation > path were found (for example through a derived CRS), then the > transformation from this > CRS to any CRS with a compatible number of dimensions is assumed to be the > identity transform. This CRS is usefull as a kind of wildcard when no > CRS were explicitly specified. > > ----------------- > > The reasoning behind this idea is that way too often people do not > have, or do not know, > the CRS of their data, and are forced to guess with a valid EPSG code. > Maybe the data has no CRS to start with (think abusing GS/OL > to make an high resolution picture browser), maybe it's a building > blueprint, or > a town level map made with CAD tools. > Or maybe it's GIS data but you just cannot find anything about the CRS > and you don't > care about reprojection to start with. > > So far the common behavior by lots of people has been using EPSG:4326. > However that comes today with too many strings attached to be used as a > default > for that case: > - it's geographic, thus it suffers from the axis flipping issue > - it can be wrapped, but the map wrapping heuristics will fail if the > data is not really > within the limits of EPSG:4326 sane values > > I guess the drawback for such a code is that it might confuse clients > that try to interpret > the codes (which are normally GIS aware ones). > > Another possible for such data might be to pretend it's in a CRS that > is projected, > has a very large (possibly infinite?) ordinate validity range and > includes 0 as valid > value.. something like EPSG:3785 would indeed fit the bill. > The drawback of this one is that it would enable the usage of the > reprojection > machinery while it makes no sense to use one. > > Opinions? > > Cheers > Andrea > > -- > Ing. Andrea Aime > Technical Lead > > GeoSolutions S.A.S. > Via Poggio alle Viti 1187 > 55054 Massarosa (LU) > Italy > > phone: +39 0584962313 > fax: +39 0584962313 > > http://www.geo-solutions.it > http://geo-solutions.blogspot.com/ > http://www.linkedin.com/in/andreaaime > http://twitter.com/geowolf > > ----------------------------------------------------- > > > ------------------------------------------------------------------------------ > Gaining the trust of online customers is vital for the success of any > company > that requires sensitive data to be transmitted over the Web. Learn how to > best implement a security strategy that keeps consumers' information secure > and instills the confidence they need to proceed with transactions. > http://p.sf.net/sfu/oracle-sfdevnl > _______________________________________________ > Geoserver-devel mailing list > Geoserver-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/geoserver-devel > -- Justin Deoliveira OpenGeo - http://opengeo.org Enterprise support for open source geospatial.
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