[Qgis-user] Errors with distances in Google Mercator Projection?

[magerlin]

I must start to admit that I am not an expert in projections but I get a
little suspicious when the ratio between ellipsoidal and non-ellipsoidal
distances is about 1.8 in Google Mercator?

I have set the project CRS to Google Mercator and have loaded a WMS also in
Google Mercator.

Trying to use the measure tool to measure the length of the scale bar from
the scalebar plugin gives the results as shown below:

http://osgeo-org.1803224.n2.nabble.com/file/n6845255/Distance_in_GoogleMercator.png 

Adding a line layer with a line at the length of the scale bar and using the
field calculator to calculate the length of the line shows that Qgis
calculates the non-elipsodial length of about 8 km:

http://osgeo-org.1803224.n2.nabble.com/file/n6845255/Line_Length.png 

>From my "real world experience" I know that the ellipsoidal distance is the
right one so the scale bar and the length calculated in the field calculator
is all wrong.

Is this an error or have I misunderstood something?

Doing the same exercise using the ETRS89 / UTM32N projection shows only a
ratio of 1.001 which is more like what I would expect.



-----
Regards Morten
(Qgis 1.7 and Win 7)
--
View this message in context: http://osgeo-org.1803224.n2.nabble.com/Errors-with-distances-in-Google-Mercator-Projection-tp6845255p6845255.html
Sent from the qgis-user mailing list archive at Nabble.com.