<div>so did you understand why?</div>
<div>lat lon is not an equidistant coordinate system. It is an angular measure. The graticules merge closer togehter the further north they go.</div>
<div>When you overlay data projected to ll onto a flat surface the lengths east west at the top are shorter than the lengths east west at the bottom.</div>
<div>that is what is changing the scale because without zooming the scale of the objects would change by panning the map north and south.</div>
<div>Nothng about the scale is changing except the distance measured across. No coordinate values.</div>
<div>HTH</div>
<div><br><br> </div>
<div class="gmail_quote">On Wed, Nov 2, 2011 at 10:12 AM, James Stott <span dir="ltr"><<a href="mailto:James.Stott@npaconsult.co.uk">James.Stott@npaconsult.co.uk</a>></span> wrote:<br>
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<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt">If I use the arrow keys to pan north and south the scale changes. If I use them to pan left and right it doesn’t change.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt"><u></u> <u></u></span></p></div>
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<p style="MARGIN-TOP: 5px; MARGIN-BOTTOM: 10px"><span style="COLOR: #00227c; FONT-SIZE: 10pt"><strong>James Stott</strong> <span style="FONT-SIZE: 8pt">BSc (Hons) MSc</span> | Senior Professional<br><span style="FONT-SIZE: 8pt"><b style="FONT-WEIGHT: bold">Nicholas Pearson Associates </b>| 30 Brock Street | Bath | BA1 2LN<br>
<b>T:</b> 01225 445548 | <b>M:</b> -<br><a style="COLOR: #00227c; FONT-SIZE: 8pt; TEXT-DECORATION: none" href="http://www.npaconsult.co.uk/" target="_blank"><strong>www.npaconsult.co.uk</strong></a> </span></span><br><br>
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<p class="MsoNormal"><b><span style="FONT-SIZE: 10pt" lang="EN-US">From:</span></b><span style="FONT-SIZE: 10pt" lang="EN-US"> <a href="mailto:kidsmake6until2019@gmail.com" target="_blank">kidsmake6until2019@gmail.com</a> [mailto:<a href="mailto:kidsmake6until2019@gmail.com" target="_blank">kidsmake6until2019@gmail.com</a>] <b>On Behalf Of </b>Brad Nesom<br>
<b>Sent:</b> 02 November 2011 15:00<br><b>To:</b> James Stott<br><b>Cc:</b> Saber Razmjooei; <a href="mailto:qgis-user@lists.osgeo.org" target="_blank">qgis-user@lists.osgeo.org</a><br><b>Subject:</b> Re: [Qgis-user] Scale seems strange in<u></u><u></u></span></p>
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<p class="MsoNormal">I am thinking rather than that it is just the fact that when you use degrees, moving in the map would give you a different scale.<u></u><u></u></p></div>
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<p class="MsoNormal">Because every time you move north or south you have changed the length of the x distance.<u></u><u></u></p></div>
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<p class="MsoNormal">If you pan left and right (very carefully) do you see the scale not change?<u></u><u></u></p></div>
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<p class="MsoNormal">On Wed, Nov 2, 2011 at 9:02 AM, James Stott <<a href="mailto:James.Stott@npaconsult.co.uk" target="_blank">James.Stott@npaconsult.co.uk</a>> wrote:<u></u><u></u></p>
<p style="MARGIN-BOTTOM: 12pt" class="MsoNormal">Could this just be a windows thing then? I tried an older version of qgis-dev (1.8.0-78) on a different windows machine in the office and there are no problems. Metres should be the default setting for 27700 shouldn't it not degrees?<br>
<br><br>James Stott BSc (Hons) MSc | Senior Professional<br>Nicholas Pearson Associates | 30 Brock Street | Bath | BA1 2LN<br>T: 01225 445548 | M: -<br><a href="http://www.npaconsult.co.uk/" target="_blank">http://www.npaconsult.co.uk/</a><br>
<br>-----Original Message-----<br>From: Saber Razmjooei [mailto:<a href="mailto:razmjooeis@faunalia.co.uk" target="_blank">razmjooeis@faunalia.co.uk</a>]<br>Sent: 02 November 2011 10:48<br>To: James Stott<br>Cc: <a href="mailto:qgis-user@lists.osgeo.org" target="_blank">qgis-user@lists.osgeo.org</a><br>
Subject: RE: [Qgis-user] Scale seems strange in<br><br>James<br><br>I am using QGIS-Trunk under ubuntu 10.04. The canvas projection is set<br>to 27700 and Layer unit to metre.<br><br>The scale seems to be fine and not affected by panning.<br>
<br>Cheers<br>Saber<br><br>On Wed, 2011-11-02 at 10:43 +0000, James Stott wrote:<br>> An update:<br>><br>><br>><br>> This is also happening on a colleague’s machine. I have reverted back<br>> to the previous OSGeo4W nightly and that doesn’t fix the problem.<br>
> Uninstalling and reinstalling doesn’t work.<br>><br>><br>><br>> In 1.7, if I open up this certain dataset of viewpoint locations, it<br>> opens with a scale of 1:53478. In 1.8 if I load the dataset it opens<br>
> at a scale of 1:5325654358. If I use the pan tool and just click on<br>> the map the scale changes to 1:631588609, then 1:2918610855, then<br>> 1:2934133484 and so on. Distance measures seem unaffected. It seems to<br>
> be being caused by the units of the project being set to degrees. I<br>> have saved a project and the units are set to degrees. If I open an<br>> old project up it opens at the correct scale. In my old project files<br>
> it is set to metres. (see examples below). It seems I have to make<br>> sure Enable on the fly projection is unticked in the project<br>> properties, and then manually set the Layer units to metres in the<br>> general tab.<br>
><br>><br>><br>> I was also having problems a while ago with exporting to MapInfo but I<br>> have just tried this and it works. See links below for details. It is<br>> including the 79 not the 104 now.<br>
><br>><br>><br>> <a href="http://gis.stackexchange.com/questions/14350/qgis-and-mapinfo-projections-epsg-27700-british-national-grid" target="_blank">http://gis.stackexchange.com/questions/14350/qgis-and-mapinfo-projections-epsg-27700-british-national-grid</a><br>
><br>> <a href="http://hub.qgis.org/issues/4271" target="_blank">http://hub.qgis.org/issues/4271</a><br>><br>><br>><br>> New project:<br>><br>><br>><br>> <mapcanvas><br>><br>> <units>degrees</units><br>
><br>> <extent><br>><br>> <xmin>384571.226869</xmin><br>><br>> <ymin>78401.536498</ymin><br>><br>> <xmax>408875.829430</xmax><br>
><br>> <ymax>92579.221325</ymax><br>><br>> </extent><br>><br>> <projections>0</projections><br>><br>> <destinationsrs><br>><br>
> <spatialrefsys><br>><br>> <proj4>+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717<br>> +x_0=400000 +y_0=-100000 +ellps=airy<br>> +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m<br>
> +no_defs</proj4><br>><br>> <srsid>2437</srsid><br>><br>> <srid>27700</srid><br>><br>> <authid>EPSG:27700</authid><br>
><br>> <description>OSGB 1936 / British National<br>> Grid</description><br>><br>> <projectionacronym>tmerc</projectionacronym><br>><br>> <ellipsoidacronym>airy</ellipsoidacronym><br>
><br>> <geographicflag>false</geographicflag><br>><br>> </spatialrefsys><br>><br>> </destinationsrs><br>><br>> </mapcanvas><br>
><br>><br>><br>> Old project:<br>><br>><br>><br>> <mapcanvas><br>><br>> <units>meters</units><br>><br>> <extent><br>><br>> <xmin>400790.090563</xmin><br>
><br>> <ymin>86512.592259</ymin><br>><br>> <xmax>401731.465923</xmax><br>><br>> <ymax>87217.568425</ymax><br>><br>> </extent><br>
><br>> <projections>0</projections><br>><br>> <destinationsrs><br>><br>> <spatialrefsys><br>><br>> <proj4>+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717<br>
> +x_0=400000 +y_0=-100000 +ellps=airy<br>> +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m<br>> +no_defs</proj4><br>><br>> <srsid>2437</srsid><br>><br>
> <srid>27700</srid><br>><br>> <authid>EPSG:27700</authid><br>><br>> <description>OSGB 1936 / British National<br>> Grid</description><br>
><br>> <projectionacronym>tmerc</projectionacronym><br>><br>> <ellipsoidacronym>airy</ellipsoidacronym><br>><br>> <geographicflag>false</geographicflag><br>
><br>> </spatialrefsys><br>><br>> </destinationsrs><br>><br>> </mapcanvas><br>><br>><br>><br>><br>><br>><br>><br>><br>> James Stott BSc (Hons) MSc | Senior Professional<br>
> Nicholas Pearson Associates | 30 Brock Street | Bath | BA1 2LN<br>> T: 01225 445548 | M: -<br>> <a href="http://www.npaconsult.co.uk/" target="_blank">www.npaconsult.co.uk</a><br>><br>><br>><br>> From: <a href="mailto:qgis-user-bounces@lists.osgeo.org" target="_blank">qgis-user-bounces@lists.osgeo.org</a><br>
> [mailto:<a href="mailto:qgis-user-bounces@lists.osgeo.org" target="_blank">qgis-user-bounces@lists.osgeo.org</a>] On Behalf Of James Stott<br>> Sent: 01 November 2011 09:15<br>> To: <a href="mailto:qgis-user@lists.osgeo.org" target="_blank">qgis-user@lists.osgeo.org</a><br>
> Subject: [Qgis-user] Scale seems strange in<br>><br>><br>><br>><br>> Hi all,<br>><br>><br>><br>> I am having problems with scales on v1.8 (7297b23) from OSGeo4W.<br>><br>><br>><br>
> If I open an existing project everything is fine.<br>><br>><br>><br>> If I open data in a fresh QGIS session it is reporting strange scales.<br>> It doesn’t matter what source the data is. For example, I open a<br>
> dataset and it reports 1:784735546. It seems to report correct<br>> distances. If I pan the scale changes.<br>><br>><br>><br>> I am using EPSG 27700 (British National Grid).<br>><br>><br>><br>
> Does anyone have any idea what can be causing this?<br>><br>><br>><br>> James<br>><br>> James Stott BSc (Hons) MSc | Senior Professional<br>> Nicholas Pearson Associates | 30 Brock Street | Bath | BA1 2LN<br>
> T: 01225 445548 | M: -<br>> <a href="http://www.npaconsult.co.uk/" target="_blank">www.npaconsult.co.uk</a><br>><br>> Nicholas Pearson Associates, LogoNicholas Pearson Associates, Latest<br>> News<br>><br>
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