Thanks a lot for your advice, Nicolas! ardi
On Thu, Jun 11, 2015 at 1:09 AM, Nicolas Cadieux <nicolas.cadi...@archeotec.ca> wrote: > Hi, > It's never a good idea to delete files that you have reprojected. > Reprojection will, in most cases slightly alter the data although that > depends on the parameters used. You could always test by reprojecting the > file back to the original projection and then by using raster math to see > the differences, if any. > > If you want to save space, I suggest you compress the data using "deflate" > parameters. (You need to manually add support for bigtiff if the file is > over 4GB. ) Once you are done, you can always do raster math to make sure > data has not changed. ( original layer - new layer should give zeros). > > For your second question, that is just the way it is! Since QGIS is open > source, not ever programmer puts reprojection in their code. > > Cheers. > > Nicolas Cadieux M.Sc. > Les Entreprises Archéotec inc. > 8548, rue Saint-Denis Montréal H2P 2H2 > Téléphone: 514.381.5112 Fax: 514.381.4995 > www.archeotec.ca > > On Jun 10, 2015 4:36 PM, "ardi [via OSGeo.org]" <[hidden email]> wrote: > > Hi, > > I've a satellite photo data set which spans across three UTM zones, > and I need to do some tasks in all three zones at once. Each image > tile from the data set is provided in two versions: one is projected > in the UTM coordinate system for the zone it actually belongs. The > other is projected over the central UTM zone, extending such central > zone. > > AFAIK, QGIS can deal with layers belonging to different UTM zones, > because you see a lat/long display and layers are reprojected to > lat/long on the fly. > > My question is: can I save disk space by storing the image tiles in > just one version, the version projected in its real UTM zone? Or would > I also need the versions projected into the (extended) central UTM > zone? > > Just out of curiosity, what's the use of the version projected into > the extended zone? Is it because some GIS packages don't support > on-the-fly reprojection? Or why? > > Thank you in advance > _______________________________________________ > Qgis-user mailing list > <a > href="/user/SendEmail.jtp?type=node&node=5210266&i=0">[hidden > email] > http://lists.osgeo.org/mailman/listinfo/qgis-user > > > ________________________________ > If you reply to this email, your message will be added to the discussion > below: > http://osgeo-org.1560.x6.nabble.com/Do-I-need-satellite-raster-layers-relative-to-an-extended-UTM-zone-tp5210266.html > To start a new topic under Quantum GIS - User, email > ml-node+s1560n4125267...@n6.nabble.com > To unsubscribe from Quantum GIS - User, <a > href="http://osgeo-org.1560.x6.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=4125267&code=bmljb2xhcy5jYWRpZXV4QGFyY2hlb3RlYy5jYXw0MTI1MjY3fDYzNDQ4MjQxNg==">click > here. > <a > href="http://osgeo-org.1560.x6.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml" > style="font:9px serif">NAML > > > ________________________________ > View this message in context: Re: Do I need satellite raster layers relative > to an extended UTM zone? > Sent from the Quantum GIS - User mailing list archive at Nabble.com. > > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-user _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user