Re: [Qgis-user] Projection Issues with GPX Files

[Carl Brown]

On Sunday 14 January 2007 1:34 pm, Magnus Homann wrote:
> When you add a new GPX-layer you should set its projection to WGS84
> (2585). Perhaps the easiest way is to go into Edit->Preferences and
> select the Projection tab. Set to "Ask..." befvore you add/create any
> layer.

Thanks. I got it working after a few tries. I ran into some issues trying to 
do what you suggested. (QGIS 0.7.4, Debian Sid AMD64)

The Settings>Preferences>Projection>Prompt for projection apparently is not 
working, since it does not prompt for projection when set. The new layer is 
created using the projection from the active GRASS location.

The Layer popup list>Properties>General>Spatial Reference System 
shows: "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs " even after it has 
defaulted to something else as mentioned above. I created a new GPX layer, 
and checked the layer projection. Then it still produced UTM numbers in the 
GPX file, even with on-the-fly projection enabled.

When On-the-fly projection is enabled, the layer projection can be changed, 
and then it works as it should.

-- 
Carl Brown
Whitefield, NH USA
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Re: [Qgis-user] Projection Issues with GPX Files

[Magnus Homann]

Carl Brown wrote:

Environment:
Running QGIS from a GRASS session.
GRASS region is using a NAD27 UTM projection (1385), because that is the 
projection used by the USGS DEM and DRG raster data.


In QGIS, I created a GPX layer, and digitized some waypoints and a route. The 
resulting GPX file contains "latitude" and "longitude" in UTM coordinates, 
which is not valid data for either gpsbabel or the GPX format. Here is one 
route point from the resulting GPX file:





Changing the projection in QGIS to WGS84 lat-lon (2585) causes the 
UTM-projected raster data to disappear from the display, which is not 
surprising, but that makes it impossible to digitize routes and waypoints 
from it while using the proper projection for the GPX file.


Is there a good way to reproject the coordinates in the GPX file, either 
on-the-fly or by post-processing the GPX file?


When you add a new GPX-layer you should set its projection to WGS84 
(2585). Perhaps the easiest way is to go into Edit->Preferences and 
select the Projection tab. Set to "Ask..." befvore you add/create any layer.


The project projection should be set to NAD27 UTM projection (1385), and 
turned on.


The Raster data should also have NAD27 UTM projection (1385) (always the 
same as project projection).


(Guys, I tihnk we need to rename project projection to something else)

--
Magnus Homann
[EMAIL PROTECTED]
+46 702 399 558
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