<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:10pt"><div style="" class="">Hi,</div><div style="" class=""><br style="" class=""></div><div class="" style="color: rgb(0, 0, 0); font-size: 13.3333px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;">Apologies for an attachment to a list email, but I kept it small...<br style="" class=""></div><div class="" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 10pt;"><div class="" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"><div style="" class=""><font style="" class="" size="2"><br style="" class="">The attached image shows some Antarctic data (grounding line & ice shelf extent)
with a polygon overlayed. <br style="" class="">I created the polygon by editing a text (csv) file with lat/longs:<br style="" class="">x,y<br style="" class="">150,-60<br style="" class="">150,-85<br style="" class="">255,-85<br style="" class="">255,-60<br style="" class=""></font><br style="" class=""><font style="" class="" size="2">I opened it in QGIS (CRS=EPSG:4326) & created a new polygon shapefile layer (snapping to the points) to create a box defined by the same points.<br style="" class=""><br style="" class="">Then I opened the Antacrctic layers (WFS from NSIDC <a style="" class="" href="http://nsidc.org/cgi-bin/atlas_south">http://nsidc.org/cgi-bin/atlas_south</a> in EPSG:3031 - Antarctic Polar Stereographic)<br style="" class=""></font></div><div> </div><font style="" class="" size="2"> </font><div style="" class=""><font style="" class="" size="2">I set the QGIS project CRS to a user defined one, same as EPSG:3031, but with
+lon_0=180 instead of 0 which gives a 180 up map instead of 0 up.<br style="" class=""><br style="" class="">The map is displayed as in the attached image - a strange box is drawn to the north of the box polygon, the eastern points & vertices do not appear - and if the layer is editable, they cannot be clicked on as nodes. <br style="" class=""><br style="" class="">If I swap the CRS to EPSG:3031, the inverted map renders the box better (no extra box outside it) but the points are still rendered in a different location to the polygon vertices - but they share the same coordinates.<br style="" class=""><br style="" class="">I can usually work around 180 issues in QGIS by using longitudes in the 0-360 space, but it seems to me that there are some issues with QGIS working in a polar projection across 180.<br style="" class=""><br style="" class="">Does anyone know if there is a way to solve this, or is this an inherent problem for now? In the short
term I need to decide whether or not I can progress with QGIS in the cross 180 polar space, or will need to find another tool.<br style="" class=""><br style="" class="">In the longer term, if this is an issue, I'd like to work with a developer to resolve it - and may be able to fund (some of?) the work required.<br style="" class=""><br style="" class=""><br style="" class="">Thanks,<br style="" class=""><br style="" class=""> Brent Wood</font><br style="" class=""></div></div> </div> <br style="" class=""><div style="" class=""></div></div></body></html>