projection error

vagtazohalottkem

Hi!

I'm using an european, so called "hd72" projections, which is a local hungarian projection. I wanted to make this report, because my friends just watched this error too.

If i create a new shape, or i project something to hd72, the ArcGis create prj file like this:
PROJCS["Hungarian_1972_Egyseges_Orszagos_Vetuleti",GEOGCS["GCS_Hungarian_1972",
DATUM["D_Hungarian_1972",SPHEROID["GRS_1967",6378160.0,298.247167427]],
PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],
PARAMETER["False_Easting",650000.0],
PARAMETER["False_Northing",200000.0],
PARAMETER["Scale_Factor",0.99993],
PARAMETER["Azimuth",90.0],
PARAMETER["Longitude_Of_Center",19.048571778],
PARAMETER["Latitude_Of_Center",47.14439372222],
UNIT["Meter",1.0]]

If i make it with GlobalMapper, it seems:
PROJCS["Hotine_Oblique_Mercator",
GEOGCS["Geographic Coordinate System",
DATUM["HD72",SPHEROID["GRS 1967 (Indonesia 1974)",6378160,298.2471674309769]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433]],
PROJECTION["Hotine_Oblique_Mercator"],
PARAMETER["scale_factor",0.99993],
PARAMETER["azimuth",90],
PARAMETER["central_meridian",19.04857166999951],
PARAMETER["latitude_of_origin",47.14439361000019],
PARAMETER["false_easting",650000],
PARAMETER["false_northing",200000],
UNIT["Meter",1]]

There are differences, witch occurs this problem: if i project a shape to hd72, and open this in arcgis, it's not in the same "place", like the shape what was projected by the ArcGis.

The first hd72 (other name Egyseges Orszagos Vetulet, EOV) description is the correct, i only saw prj files, like this. The second, i think, probably bad. Here is a link about the hd72/EOV projection:

http://spatialreference.org/ref/epsg/23700/

Best regards,

v.

global_mapper

I have updated Global Mapper to use the same name for the datum in PRJ files as ESRI so that ESRI products can recognize it. I also slightly tweaked the Hungarian EOV meridian and latitude parameters so they exactly match the other, but the differences should have been very tiny. I have placed a new build at http://www.globalmapper.com/global_mapper13.zip with the latest changes for you to try. Simply download that file and extract the contents into your existing v13.xx installation folder to give it a try. If you are using the 64-bit v13 version there is a new build at http://www.globalmapper.com/global_mapper13_64bit.zip . With those changes now when I load the PRJ file from ArcGis Global Mapper recognizes it as the Hungarian EOV projection with the HD72 datum.

Let me know if I can be of further assistance.

Thanks,

Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com

vagtazohalottkem

Hi Mike!

I think you are wrong. The problem is with the GM's projection definition. If i load anything into GM, for example a wgs 84 projected data, and i set new projection, and export to vector, then i load that into ArcGis, it's not in the correct place. My friend tested, if he deleted the prj file from the exported raster/vector, the ArcGis can't identify the projection, shows unknow proj/unknows unit, but drawed into the right place. I think, there is something in the global mappers hd72 projection progress.

cheers

v.

global_mapper

It sounds like the actual projection of the data is correct in Global Mapper, but ArcGis is not interpreting the PRJ file the same as Global Mapper does. Can you tell in ArcGis what projection is being assumed for the PRJ from Global Mapper? The Global Mapper PRJ file is nearly identical (differences only in name, which doesn't matter, and extremely small difference in ellipsoid base for HD72 datum) from the standard OGC WKT PRJ definition (see http://spatialreference.org/ref/epsg/23700/prettywkt/). This is really what software should be using for projection definitions, but Esri likes to go their own way and do incompatible things. As you can see in the OGC WKT definition the projection name is 'Hotine_Oblique_Mercator', the same as in Global Mapper's PRJ file, while ArcGis uses 'Hotine_Oblique_Mercator_Azimuth_Center'. Global Mapper interprets those the same, but it sounds like ArcGis may be doing something else entirely with just 'Hotine_Oblique_Mercator' as the text as the OGC standard uses. The other projection parameters are the same. If you add '_Azimuth_Center' to the PROJECTION[ name in the Global Mapper-generated PRJ file does ArcGis then interpret the location correctly?

Thanks,

Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com

vagtazohalottkem

Hmm, actually, i tested it:
- i wrote the azimuth center part to the prj, does not matter, projected wrong.
- i saw the properties in the Arcmap and there are some differences: the good projected, hd72 files showing with latitude/longitude paramters, but the GM projected shape shows hotine oblique mercator azimuth center, under that hotine oblique mercator azimuth natural origin, and under that false easting, northing, central meridian, scale factor, latitude of origin, azimuth, and there is nothing about the longitude....

Our solution was the uncheck prj file creation in GM, because arcmap can project with unknown projection, and if we need, we can define.

I think you are right, something is bad by the esri's house. But the hd72 can't work in the arcmap, it's a real problem for us.

here is a link to a rar file, with two shapefiles, with the same thing. The two prj isn't the same, check with arcmap and with gm.

http://s3.toldacuccot.hu/letoltes?sid=af00787a9723237d557bfa1a5c51ade6&file=file.rar

cheers

global_mapper

I can't believe I didn't see this before, but I just noticed that Global Mapper is writing out the Azimuth Point parameter for this projection as Central_Meridian while Esri and OGC WKT is using Longitude_of_Center. While Global Mapper is smart enough to recognize either of those as mapping to Azimuth Point, apparently Esri is not. I have switched Global Mapper to write out Longitude_of_Center and I think that will take care of the issue! I have placed a new build at http://www.globalmapper.com/global_mapper13.zip with the latest changes for you to try. Simply download that file and extract the contents into your existing v13.xx installation folder to give it a try. If you are using the 64-bit v13 version there is a new build at http://www.globalmapper.com/global_mapper13_64bit.zip .

Thanks,

Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com

vagtazohalottkem

Hi Mike!

Yeah, before, some month i used GM, and i don't saw any problem with hd72. But now that small problem was annoying. I've tested that, and now it's working. Thank you Mike!

Best regards,
V.