I have a polygon grid of a certain shape that has some data associated with it. Unfortunately its not properly projected, being in what seems to be an arbitrary scale and coordinate system (it was originally a DXF). I need to reproject this.

The grid cells are about 8 * 11 "units" (I'm going to guess metres - it looks like a "projected" system). I need them to be 3000 * 4000 metres (OSGB).

How do I reproject this grid into the desired new grid? Once its been "resized", I can then easily offset it to georeference it properly.

I have access to FME.

  • Thanks, but having now read that, I already know the coordinate system it in is pretty much OSGB. Its just that when the data was digitised it wasn't properly georeferenced so everything is about 375 times smaller than it should be and badly offset too. The later I can fix; I'm trying to figure out how to make the polygons bigger. – GIS-Jonathan Jul 27 '12 at 8:43

If the features all need increasing by the same size, there is a Scaler transformer in FME. But I'd be tempted to warp/rubbersheet the data into position, unless I was really sure the resizing was consistent.

  • Scaler did it (and now I know about a new transformer), plus with an offset afterwards to put it in the right place. But how would you warp/rubbersheet it? – GIS-Jonathan Jul 31 '12 at 11:27
  • There are Affiner and RubberSheeter transformers. Which you use would depend on whether you know a set of offsets/scaling to make (the Affiner parameters) or whether you can define a set of offset features that define a set of warp vectors. I often use that latter option. It's not as complicated as it sounds. – Mark Ireland Jul 31 '12 at 14:36

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