Andrea Aime wrote: > Bryce L Nordgren ha scritto: >> I missed the discussion, but I agree wholeheartedly with this email! >> >> 1] No one-size-fits-all hint. >> 2] Internal data models adopt a single axis convention. (no hints at >> all; >> just use CRS order) > > Sorry, my understanding of Rob proposal was that everybody should use > long/lat axis order internally. > This was an idea (for discussion) driven by the fact that the CRS order is not reliably inferred - there are multiple representations of nominally the same CRS (EPSG:XXX, URN, URI, WKT) but different (and not clear to anybody as far as I can tell) business rules about how to interpret in different circumstances.
So, I'm not concinced its actually possible to use the CRS order :-( Maybe the mapping of the different authority root to a CRS with a single identifiable authority is a solution. Apropos the axis swapping overhead, this is a engineering issue that may be solvable. Lets look at the performance bottlenecks: 1) WMS rendering - this is critical because WMS may serve very large number of features, or coverage elements rendered into an image response. WMS is going to need to swap to X,Y order anyway - so having that order internally means that the minimum number of swaps possible is done. 2) Coverage subsetting - this involves a large number of elements, but as serialising into an axes-order specific format is required anyway. The axis ordering may only be required within the metadata (encapsulating general feature that describes the domain and range data streams). There may be no need to swap order in the data streams as long as the metadata was useful. In general, this may be necessary for nD coverages anyway? What other operations require treatment of large amounts of data? In general, WFS should be used for predicatable quantities of data, or used in a low-transaction-volume mode (monthly update distrubution etc). The cost of the order would be minimal. Rob > This would have scary performance consequences on both rendering and > WFS serving because the data stores would have to provide data in > that order, maybe just to re-swap them again if the required CRS > for output is swapped again... (hint: on rendering we do reproject > after decimation, so we do reproject just a minimal part of the > original points). > > I know having to deal with axis swap is complicated on the source > code level, but forcing an order on the data store has its problems > too. > > Maybe I'm just misunderstanding? > Cheers > Andrea ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
