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I have a multipatch feature class which comes from a conversion of a IFC model. Its coordinate system is very strange ("IFC_COORD_SYS_0") and I'd like to change it to EPSG:32632.

I am using ArcGIS Pro.

As the project tool fails (it shows an "extent error" message), my way to go was to:

  • use the Define Projection tool to set its coordinate system to EPS:32632.
  • Move everything with the Move To tool to my area of interest, having the Map Frame coordinate system set to 32632 as well.

Doing so, the layer looks in the right place, but it spans over regions while it is supposed to be just a single building. I suppose the problem is that its usints are millimeters rather than meters.

I think I need to make a custom PRJ with millimeters units. My idea was to save projection as EPSG:32632 as prj file, and modify it from METERS to MILLIMETERS units. But, I have some problems in doing so, as when I assign the new custom PRJ my layer shows up in the wrong place all the time.

Below are both the original (in meters) and the modified (in millimeters) PRJ files. What could I have done wrong?

EPSG:32632 (METERS)

PROJCS["WGS_1984_UTM_Zone_32N",
    GEOGCS["GCS_WGS_1984",
        DATUM["D_WGS_1984",
            SPHEROID["WGS_1984",6378137.0,298.257223563]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["False_Easting",500000.0],
    PARAMETER["False_Northing",0.0],
    PARAMETER["Central_Meridian",9.0],
    PARAMETER["Scale_Factor",0.9996],
    PARAMETER["Latitude_Of_Origin",0.0],
    UNIT["Meter",1.0],
    AUTHORITY["EPSG",32632]]

EPSG:32632 (MILLIMETERS)

PROJCS["WGS_1984_UTM_Zone_32N_MM",
    GEOGCS["GCS_WGS_1984",
        DATUM["D_WGS_1984",
            SPHEROID["WGS_1984",6378137.0,298.257223563]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["False_Easting",500000000.0],
    PARAMETER["False_Northing",0.0],
    PARAMETER["Central_Meridian",9000.0],
    PARAMETER["Scale_Factor",0.9996],
    PARAMETER["Latitude_Of_Origin",0.0],
    UNIT["MILLIMETER",1]]
  • 1
    The UNIT["MILLIMETER",1] should be UNIT["MILLIMETER",0.001] (linear units are defined in meters) – Vince Oct 9 '18 at 13:33
  • 1
    Also change the central meridian back to 9.0. – mkennedy Oct 9 '18 at 19:35
  • Thanks for your suggestions. I did solve my issue asking to export the IFC model again in metrical units and everything looked fine. However, for the sake of curiosity, I tried chaning the prj file again with your suggestions but unfortunately with no better results: the dataset goes in the center of 32632 projection (roughly in 0,0) and nothing shows up, don't know why... – umbe1987 Oct 10 '18 at 7:56

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