I just want to raise an issue with importing/exporting from scenes using the Australian MGA projection system (GDA 1994 MGA Zone 56). All of my .shp files which are currenlty projected in MGA Zone 56 always default to a custom coordinate system when imported and do not use the predefined coord system. When I then try to export models as COLLADA from the MGA scene they do not end up in the correct geo-position ( In fact they are not even positioned on the globe? ).
I can convert the .shp files to another coord system ( say World Mercator WGS84 ) and then export into the correct position but this results in subtle errors to the shapefiles positioning which is not permissible for my uses.
1. Is there a way I can force CE to use the predefined coord system and not default to a custom system? 2. Are there any known issues with the way CE handles the Australia National Grids?
Solutions There are several ways to solve this. Choose the one you like best ;)
Export your data to a file GDB instead of shapefile, and use CityEngine's file GDB importer. This importer picks the correct EPSG system, instead of a custom one.
Delete the .prj file before importing the .shp file. CityEngine then asks to choose a coord system. In the top "search expression" field, enter *28356* (epsg code enclosed by wildcard character *), or manually browse to the correct coordinate system.
manually add the epsg code to the very end of the .prj file: change
. On shapefile import, CityEngine will pick the correct coord system.
Instead of manually modifying the prj, download the OGC WKT file of your coord system from here http://spatialreference.org/ref/epsg/28356/, and overwrite your current .prj file with this one. On shapefile import, CityEngine will pick the correct coord system.
Explanation CityEngine uses a different projection and coord sys library than ArcGIS, which can cause issues in some situations. Whenever an authority code (e.g. EPSG:28356) is present in the import data, CityEngine can reliably pick the correct coordinate system. If no authority code is available, picking the "official" (non-custom) coord system is not guaranteed. Unfortunately ArcGIS shapefile exporter does not write the authority code to the prj file (at least as far as I know), which is why in certain cases manual intervention is required on import, as described above. The File GDB Exporter in ArcGIS on the other hand writes the authority code.
Did a manual change using Notepad++ but will use the geodatabase option in the future. I have attached a screen capture of part of our static models dataset imported into ArcGlobe, the pipeline from CE to Arc is now running well!