Custom projection problem
Hi!
I have a question about custom projections in Locus.
Is it possible to define custom projection not entierly based on EPSG codes?
Here in Slovenia we also use Gauss-Krueger grid, inherited from former Austria and Yugoslavia.
The correcrt EPSG code is 3787 (MGI / Slovene National Grid) but the values for X-coordinate are 300m lower.
It is a interresting story how this had happen:
The MGI datum, used in Austria and former Yugoslavia, was originally based on the Ferro meridian, not Greenwich.
According to the European longitude adjustment of Theodor Albrecht (ca. 1890) the Ferro meridian is 17° 39' 46.02" west of the Greenwich meridian.
But for the geodetic networks of Austria, Germany and Czechoslovakia, the value 17° 40' 00" was adopted in the 1920s ...
When Greenwich replaced Ferro as the prime meridian in the 1920s, Yugoslavia was politically (and geodetically) independent from Austria.
When the mapmakers in Austria and Yugoslavia decided to adapt MGI to the Greenwich meridian, they used different values for the longitude of Ferro.
In Austria, they assumed that Ferro was at 17° 40' 00" West of Greenwich, which is the value given by EPSG.
But in Yugoslavia, they assumed that Ferro was at 17° 39' 46" West of Greenwich.
This results that MGI (Greenwich) in Austria differs from MGI (Greenwich) in Yugoslavia by about 14 arc seconds of longitude and abrupt 300 meter
discontinuity at a present boundary between Austria and Slovenia...
Well my question is: is it possible to "tell" Locus just to add 300m to X-coordinate, derived from ESPG:3787? Or is there another approach needed?
Regards,
Mitja
The same question
Hello Mitja,
interesting story and nice question, thank you.
I found topic with a lot of interesting links here http://gis.stackexchange.com/questions/43402/reprojection-from-wgs-to-slovenian-gauss-kruger-in-qgis , but to be true, I don't want to spend afternoon by reading about this problematic.
Currently Locus has inside a txt file with predefined EPSG codes, which are used. Thanks to external txt file is possible to add again only EPSG code, not transformation parameters directly.
Because this is really rare case (projection without EPSG code - is it even possible?), I have to say sorry, because feature what you need (transformation parameters directly), is not planned for Locus application.
Hello Mitja,
interesting story and nice question, thank you.
I found topic with a lot of interesting links here http://gis.stackexchange.com/questions/43402/reprojection-from-wgs-to-slovenian-gauss-kruger-in-qgis , but to be true, I don't want to spend afternoon by reading about this problematic.
Currently Locus has inside a txt file with predefined EPSG codes, which are used. Thanks to external txt file is possible to add again only EPSG code, not transformation parameters directly.
Because this is really rare case (projection without EPSG code - is it even possible?), I have to say sorry, because feature what you need (transformation parameters directly), is not planned for Locus application.
Menion,
thank You for your post!
Anyway, IMO this curious behavior has been worth mentioning. BTW Croatia and Bosnia experience the same problem when dealing with G-K coordinates.
Technically it doesn't affect the transformation, it is only a fixed shift cca 300m along x-axis.
Sincerely, Mitja
Menion,
thank You for your post!
Anyway, IMO this curious behavior has been worth mentioning. BTW Croatia and Bosnia experience the same problem when dealing with G-K coordinates.
Technically it doesn't affect the transformation, it is only a fixed shift cca 300m along x-axis.
Sincerely, Mitja
Replies have been locked on this page!