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On May 14, 2009, at 8:32 , andrea antonello wrote:
If I remember correctly the measure taken is the diagonal of the
viewport and the scale is calculated referring to the OGC defined
screen dpi and is hardcoded.
Thanks Jody and Andrea!
Switching from UTM 32N to unprojected for my area, the scale is the
same but the image is squeezed vertically. So, I think the scale is
measured horizontal only. ArcGIS behaves the opposite way, so it looks
like they are using vertical scale.
Googling "OGC defined screen dpi" led me to http://javadoc.geotools.fr/2.3/org/geotools/renderer/lite/RendererUtilities.html
that states that the OGC defined DPI is 90. Is that correct? Is
looks like my uDig 1.1.1 uses 72.
I am creating a WMS server and there are some viewing rules that are
based on the scale. Yes, I know it is almost impossible to do this
correctly as I do not know the client DPI and if they use horizontal,
vertical or diagonal scale.
Regards,
- Tore.
