<p dir="ltr">Hi,<br>
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.</p>
<p dir="ltr">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).</p>
<p dir="ltr">For your second question, that is just the way it is! Since QGIS is open source, not ever programmer puts reprojection in their code. </p>
<p dir="ltr">Cheers.</p>
<p dir="ltr">Nicolas Cadieux M.Sc.<br>
Les Entreprises Archéotec inc. <br>
8548, rue Saint-Denis Montréal H2P 2H2<br>
Téléphone: 514.381.5112 Fax: 514.381.4995<br>
www.archeotec.ca</p>
<div class="gmail_quote">On Jun 10, 2015 4:36 PM, "ardi [via OSGeo.org]" <<a href="/user/SendEmail.jtp?type=node&node=5210288&i=0" target="_top" rel="nofollow" link="external">[hidden email]</a>> wrote:<br type='attribution'><blockquote style='border-left:2px solid #CCCCCC;padding:0 1em' class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi,
<br /><br />I've a satellite photo data set which spans across three UTM zones,
<br />and I need to do some tasks in all three zones at once. Each image
<br />tile from the data set is provided in two versions: one is projected
<br />in the UTM coordinate system for the zone it actually belongs. The
<br />other is projected over the central UTM zone, extending such central
<br />zone.
<br /><br />AFAIK, QGIS can deal with layers belonging to different UTM zones,
<br />because you see a lat/long display and layers are reprojected to
<br />lat/long on the fly.
<br /><br />My question is: can I save disk space by storing the image tiles in
<br />just one version, the version projected in its real UTM zone? Or would
<br />I also need the versions projected into the (extended) central UTM
<br />zone?
<br /><br />Just out of curiosity, what's the use of the version projected into
<br />the extended zone? Is it because some GIS packages don't support
<br />on-the-fly reprojection? Or why?
<br /><br />Thank you in advance
<br />_______________________________________________
<br />Qgis-user mailing list
<br /><a href="/user/SendEmail.jtp?type=node&node=5210266&i=0">[hidden email]</a>
<br /><a href="http://lists.osgeo.org/mailman/listinfo/qgis-user" target="_top" rel="nofollow" link="external">http://lists.osgeo.org/mailman/listinfo/qgis-user</a><br />
<br />
<br />
<hr noshade="noshade" size="1" />
<div style="color:#444;font:12px 'tahoma' , 'geneva' , 'helvetica' , 'arial' , sans-serif">
<div style="font-weight:bold">If you reply to this email, your message will be added to the discussion below:</div>
<a href="http://osgeo-org.1560.x6.nabble.com/Do-I-need-satellite-raster-layers-relative-to-an-extended-UTM-zone-tp5210266.html" target="_top" rel="nofollow" link="external">http://osgeo-org.1560.x6.nabble.com/Do-I-need-satellite-raster-layers-relative-to-an-extended-UTM-zone-tp5210266.html</a>
</div>
<div style="color:#666;font:11px 'tahoma' , 'geneva' , 'helvetica' , 'arial' , sans-serif;margin-top:0.4em;line-height:1.5em">
To start a new topic under Quantum GIS - User, email ml-node+s1560n4125267h38@n6.nabble.com <br />
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>.<br />
<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</a>
</div></blockquote></div>
<br/><hr align="left" width="300" />
View this message in context: <a href="http://osgeo-org.1560.x6.nabble.com/Do-I-need-satellite-raster-layers-relative-to-an-extended-UTM-zone-tp5210266p5210288.html">Re: Do I need satellite raster layers relative to an extended UTM zone?</a><br/>
Sent from the <a href="http://osgeo-org.1560.x6.nabble.com/Quantum-GIS-User-f4125267.html">Quantum GIS - User mailing list archive</a> at Nabble.com.<br/>