In this case you a probably better of making copies of the files with all the same CRS.
On Fri, Feb 21, 2014 at 11:41 AM, Jonathan Moules < jonathanmou...@warwickshire.gov.uk> wrote: > Hi List, > Two issues, > > First, I'm noticing that quite a few of the layers we have that are in > British National Grid aren't actually treated that way when I load them > into QGIS. This seems to be because they have a very slightly different > definition than the one QGIS has. > For example: > > +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 > +ellps=airy +towgs84=375,-111,431,0,0,0,0 +units=m +no_defs > > +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 > +ellps=airy +towgs84=446.448,-125.157,542.06,0.1502,0.247,0.8421,-20.4894 > +units=m +no_defs > > QGIS definition > +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 > +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 > +units=m +no_defs > > Three different definitions for the same thing. > This becomes a problem because On The Fly reprojection (which I've now > been forced to disable permanently) is super slow. Even a simple polygon > layer with a few dozen features on top of a WMS creates a very noticeable > (several seconds) lag. > > So my question: > Is it possible to make QGIS recognise all the different definitions as one > single definition? > > Using a Master build from a couple of months ago. > > Thanks, > Jonathan > > This transmission is intended for the named addressee(s) only and may > contain sensitive or protectively marked material up to RESTRICTED and > should be handled accordingly. Unless you are the named addressee (or > authorised to receive it for the addressee) you may not copy or use it, or > disclose it to anyone else. If you have received this transmission in error > please notify the sender immediately. All email traffic sent to or from us, > including without limitation all GCSX traffic, may be subject to recording > and/or monitoring in accordance with relevant legislation. > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-user >
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