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CityGML LoD2 problem with coordinate transformation

  • 7 February 2018
  • 3 replies
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P

Hello everyone,

I have a problem with coordinate transformation with data in citygml format with LoD2 and to write to another citygml file. I use CsmapReprojector, define transformation parameters XFORM_DEF and nothing. My input data is in EPSG:31277 and that is Gauss-Kruger projection and it is deprecated. I want to transform data to EPSG:4326 or 3857 or 32634 on WGS ellipsoid because i want to use 3DcityDB import/export toll.

Data in input projection:

and after transformation i get this:

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Best answer by daveatsafe 9 February 2018, 00:40

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daveatsafe
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Hi @petar3bursac,

EPSG:4326 is a lat/long coordinate system. Converting into this will change the X and Y units to degrees, but leaves the X units as meters. Since the Data Inspector does not reproject the data in the 3D view, the lat/long data will look very distorted.

If you convert to EPSG:3857, which has X,Y and Z in meters, the output should look better.

P

Hi @petar3bursac,

EPSG:4326 is a lat/long coordinate system. Converting into this will change the X and Y units to degrees, but leaves the X units as meters. Since the Data Inspector does not reproject the data in the 3D view, the lat/long data will look very distorted.

If you convert to EPSG:3857, which has X,Y and Z in meters, the output should look better.

Hi @DaveAtSafe,

 

Thank you! I understand. I have one more question, please. I use CoordinateExtractor, extract x,y,z coordinates from citygml file to one shapefile, and that shp file in one GIS software open,modify and do coordinate transformation. Now i have all my coordinates in one csv file in three columns, which is ordered in same way like i get from CoordinateExtractor. My question is how to specify in CoordinateReplacer in field for x, y, z coordinate for input (citygml file) that i want to replace with my columns from csv file? I try Find:@YValue(1)? Thank you!

 

daveatsafe
Rank
Userlevel 2
Badge +17
Hi @DaveAtSafe,

 

Thank you! I understand. I have one more question, please. I use CoordinateExtractor, extract x,y,z coordinates from citygml file to one shapefile, and that shp file in one GIS software open,modify and do coordinate transformation. Now i have all my coordinates in one csv file in three columns, which is ordered in same way like i get from CoordinateExtractor. My question is how to specify in CoordinateReplacer in field for x, y, z coordinate for input (citygml file) that i want to replace with my columns from csv file? I try Find:@YValue(1)? Thank you!

 

Hi @petar3bursac

 

That process will only work for point features, I'm afraid. The CoordinateExtractor only returns a single coordinate, even from complex surface geometries like those in CityGML, so you are losing most of the geometry information.

 

FME has a number of transformers that you can use to do the desired coordinate transformation. As well as the CsmapReprojector, there are the 3DAffiner, Scaler, Offsetter and Rotator transformers.

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