Using some kind of reprojection in the middle would be ok but would consume resources as Bob mentioned. Although if you are displaying your data in large scales, staying with 4326 should be ok for visualization. In one of my apps I display data that comes in 4326 over google maps and I am happy with the accuracy even though the data is fairly detailed - planning information with extents derived from catastral boundaries. So I'd say if you are presenting your data at a county, or city level or in larger scales you should not notice any particular problems. If you are to display your data at a country or continental level do consider a reprojection.
You mentioned your data appears in the right position over your basemap. I think this should be your benchmark actually. If it looks ok, and you don't need a razor sharp accuracy stay with what looks ok and works already. -----Original Message----- From: openlayers-dev-boun...@lists.osgeo.org [mailto:openlayers-dev-boun...@lists.osgeo.org] On Behalf Of ray.diciaccio Sent: Friday, May 20, 2011 5:05 PM To: d...@openlayers.org Subject: [OpenLayers-Dev] RE: WMS request mod Ok, so it sounds to me like the "right" way to do this would be to follow Bob's suggestion and use some middleware piece to do the reprojection -- that way I wouldn't need to worry about the distortion? - Ray Dominik Mikiewicz wrote: > > Yeah, I should have added - large scales are fine (> 1m, 500k), small are > distorted. > > -----Original Message----- > From: andreas.hoce...@gmail.com [mailto:andreas.hoce...@gmail.com] On > Behalf > Of Andreas Hocevar > Sent: Friday, May 20, 2011 9:26 AM > To: Dominik Mikiewicz > Cc: Ray Di Ciaccio; openlayers-dev@lists.osgeo.org > Subject: Re: [OpenLayers-Dev] WMS request mod > > This approach will only work well for tiles that are near the equator, > or don't span over a wide range of latitudes. It is basically the same > thing that happens when you use the not recommended reproject: true > option for Layer.WMS. > > Andreas. > > On Fri, May 20, 2011 at 8:54 AM, Dominik Mikiewicz > <dominikmikiew...@o2.pl> wrote: >> This should work just fine. There won't be a serious performance hit > either as you only recalculate bbox and change srs on the clientside. I do > it quite often and even extended a wms layer class so I can quickly set up > my 4326 layers to work with spherical Mercator. >> However you may experience some issues with tile caching as sometimes the > precision may vary from browser to browser. Another thing is the > getFeatureInfo request - make sure you send correct cords if you are going > to use it. >> dom >> >> -----Original Message----- >> From: openlayers-dev-boun...@lists.osgeo.org > [mailto:openlayers-dev-boun...@lists.osgeo.org] On Behalf Of Ray Di > Ciaccio >> Sent: Thursday, May 19, 2011 6:00 PM >> To: openlayers-dev@lists.osgeo.org >> Subject: [OpenLayers-Dev] WMS request mod >> >> Sorry for the previous messed up message. Let me try this again: >> >> Hi all, >> >> I'm in what I'm guessing is a fairly common situation -- I'm using >> Google Maps as my baselayer (so map is in EPSG:9009l3 projection) and >> I'm trying to load an overlay from a WMS which I have no control over. >> It only offers data in EPSG:4326. The WMS request generated by >> OpenLayers will be for CRS=EPSG:900913 and the BBOX values will be in >> EPSG:900913. This obviously won't work if the WMS only offers EPSG:4326. >> My solution to this problem was to override >> OpenLayers.Layer.WMS.getFullRequestString() so that it uses the >> projection that I set for that particular layer -- it changes the >> CRS/SRS param to whatever the layer projection is, and it transforms the >> BBOX values from the map projection to the layer's projection. This way >> I get a valid request for the WMS and it's loaded in the correct >> location on the basemap. My question is whether this is the right >> approach to this situation and whether there may be unforeseen >> repercussions to these changes I made. >> >> Thanks! >> - Ray >> >> -- >> Ray Di Ciaccio >> MIT LL, Group 42 >> 781-981-2024 >> ray.diciac...@ll.mit.edu >> >> _______________________________________________ >> Dev mailing list >> d...@lists.osgeo.org >> http://lists.osgeo.org/mailman/listinfo/openlayers-dev >> >> _______________________________________________ >> Dev mailing list >> d...@lists.osgeo.org >> http://lists.osgeo.org/mailman/listinfo/openlayers-dev >> > > > > -- > Andreas Hocevar > OpenGeo - http://opengeo.org/ > Expert service straight from the developers. > > _______________________________________________ > Dev mailing list > d...@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/openlayers-dev > -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/WMS-request-mod-tp6382611p6386429.htm l Sent from the OpenLayers Dev mailing list archive at Nabble.com. _______________________________________________ Dev mailing list d...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/openlayers-dev _______________________________________________ Dev mailing list d...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/openlayers-dev
