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GIS vs DWG Coordinates mess


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If anyone can give me a hint on what I am doing wrong?

I have a DWG file which I want to georeference in UTM. The CAD file's metric coordinates, as imported into VW, match VW's metric coordinates (considering the particular UTM zone and hemisphere I'm using). I then georeference this layer without transforming geometry, and export it as a shapefile. I open QGIS, set the coordinate system to the same I was using in VW, and import the shapefile. Mess #1: the coordinates in QGIS turn out completely different from those in the VW file, and a site in the southern hemisphere ends up in the North Sea!

Now I get a shapefile generated in ArcMap, which opens with the correct coordinates in QGIS. I set VW's coordinate system to match that of the GIS, and import the shapefile. Mess #2: the coordinates again turn out all wrong.

Is this behavior somehow supposed to make sense?

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Yes? My current results are:

-Exporting shapefile from Mess #2 (which was in WGS84) back into GIS: coordinates are right again. Reimporting this shapefile back into VW will only line up with the previous import if I manually set the layer to WGS84. Using the shapefile's .prj (even if it was set to WGS84 to begin with) will not line up.

-georeferencing my CAD layer from Mess #1 will not line it up with the shapefile's coordinates, whether I transform the geometry or not.

I can see some consistency in the shapefile import/export behavior, but I can't seem to understand why Vectorworks will not use the UTM metric coordinates when positioning the shapefiles. That is, if I have a shapefile projected in UTM/WGS84, GIS will correctly give me *both* the metric coordinates for my current zone/hemisphere *and* the latitude/longitude. On the other hand, Vectorworks' coordinate system, which is only metric as far as I can see, does not match the actual UTM metric coordinates at all.

A concrete example: I have a point with UTM coordinates 211,800 x 8,274,000 in the 23S zone. In the CAD file I imported first, this point has proper coordinates x=211,800, y=8,274,000, and so it is imported into VW with the same coordinates. When I import the same point from a shapefile (which was displaing the correct coordinates in GIS), however, VW shows this point as being near x=(-5,909,088) and y=(-1,725,144). I suppose this is relative to a "world origin" at latitude=0 and longitude=0, however it is very counterintuitive.

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hi

i have had this problem before. i am in the uk and generally use OSGB36 co-ordinates. i came across this problem when someone sent me WGS84 co-ordinates and i tried to put them into VW, and it put things in the wrong place. the way i got round it was to convert WGS84 to OSGB36.

someone may be able to shed some light on why this is.........

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