[Mapbender_dev] EPSG:4326 tend to take random values even though maps are nearly the same

[Abhishek Singh]

Hi Marc,

Please have a look at
http://www.mapbender.org/User_talk:Abhishek#Scale_calculation_for_non-metric_SRS.
I have written code that is compliant as per that documentation. As per as I
know if I modify getScale() in http/javascripts/mab_obj.js, then the values
in case of epsg:4326 and epsg:31467 should appear nearly equal. But they
they don't appear so. If you have some idea about why the problem
is occurring and how to remove that error, please feel free to share.

Thanks,

Abhishek Kumar Singh
BE/1349/2007
Information Technology
6th SEMESTER
BIT MESRA


On Fri, May 21, 2010 at 2:39 PM, Marc Jansen <jansen at terrestris.de> wrote:

>  Hi Abhishek,
>
> just a quick guessing here, but with a geographic projection like 4326
> scale isn't trivial to calculate, as there are AFAICT two scales to be
> considered (at the poles the metric distance between lon-values is zero).
> With Mercator-based projections both axises share the same scale.
>
> I am always more or less unsure about this stuff, so if the above contains
> errors, don't throw stones at me.
>
> Regards,
> Marc
>
>
>
>
> On 20.05.2010 10:33, Abhishek Singh wrote:
>
> Hi,
>
> I am having some problem with the scales values that appear in case of
> epsg:4326 and epsg:31467 in gui1. I have modified the getScale(), code
> snippet is available at http://osgeo.pastebin.com/U44pVU2v .The problem is
> that even though maps nearly appear to be the same for epsg:4326 and
> epsg:31467, the scale values aren't showing that correspondence. The scale
> values in case of epsg:4326 tend to take scale values like 1:14, 1:19 etc.
> please suggest how to remove that error.
>
> Thanks,
>
> Abhishek Kumar Singh
> BE/1349/2007
> Information Technology
> 6th SEMESTER
> BIT MESRA
>
>
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