[Qgis-user] EPSG of data from Manifold?

[Andre Joost]

Am 20.07.2016 um 08:28 schrieb Andre Joost:
> Am 19.07.2016 um 21:05 schrieb Bernd Vogelgesang:
>> Hi,
>> we just received some shapes accompanied by an xml and no prj.
>> So far I was out of luck finding the proper projection for this, but I'm
>> guessing that this stuff is from Manifold (my first contact with that)
>>
>> Can anyone tell me from the xml what would be the related EPSG code for
>> this data?
>>
>> <?xml version="1.0" encoding="UTF-8"?>
>> <data>
>>      <coordinateSystem>
>>          <name>Orthographic</name>
>>          <datum>World Geodetic 1984 (WGS84)</datum>
>>          <system>Orthographic</system>
>
> I have not much experience with Manifold, but I guess it should be an
> orthographic projection. In that case, looking in the EPSG database may
> be useless. You would have to create a custom CRS for it.
>


Reading 
http://www.cartoninjas.net/post/Defitions-of-Polish-projections-for-manifold 
and the xml file linked there, it is definitely from Manifold. So lets try:

+proj=ortho +lat_0=0 +lon_0=0 +x_0=4393181.425 +y_0=5437772.5 
+ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs

I'm not sure about the difference between false easting and OffsetX. 
Maybe you have to enter negative values. And localScaleX and localScaleY 
is strange. Maybe it can be put in +to_meter (or 1/3.175=0.31496?) 
instead of +units=m.

Can you load the file into QGIS, and post the extent in map units, as 
reported by layer -> properties -> metadata -> Properties -> Extent?

HTH,
André Joost