I have got a dwg file with the plans for a building, with rooms and everything. (There's been some samples taken inside the building which I want to display.) Now, since it's of a building, the person making this dwg file didn't care much for coordinate systems, and it's all in some (supposedly) arbitrary system centered around the building. This is not an issue.

The problem is that this file (which I have converted to shapefiles) does not honor North being upwards, and that is what I now need to fix. Basically I want all my shapefiles to be rotated 90 degrees, so that North is upwards. It doesn't really help to rotate my data frame, since that would only change North inside my document and not for my shapefiles' coordinates.

Can I change the content of the prj-file in some way, or how could I achieve this?

Using ArcMap 10.2 basic, Python 2.7, FME 2014, Win 7.

  • Doing what you describe used to be very easy in ArcInfo Workstation via its TRANSFORM command and tic coordinates. This Q&A talks about its equivalent being Spatial Adjustment so that may be worth investigating. – PolyGeo May 19 '14 at 7:55
  • Thanks for the tip @PolyGeo. I thought about Spatial adjustment, but I ruled it out since I didn't have any other data of that area with a known projection. Still, that might be the way to do it, maybe with some OSM data as background. – Martin May 19 '14 at 10:51
  • I take it having the creator give you an updated dwg with the correct north orientation isn't an option? How many shapefiles? There is a rotate tool when editing geometry which you can enter specific angle of adjustment into. But I don't think you can do them all at once since they're in separate shapefiles - as feature classes I believe you could. And I'm betting everything is 'exploded' so rotate would do it per element, not per file. – Chris W May 19 '14 at 19:37
  • It looks like both ET GeoWizards and Hawth's Analysis Tools have a utility for this. Would either of those work? – Chris W May 19 '14 at 19:45
  • The dwg is several years old, I doubt I can even find out who made it. Although, if there's an easier way of dealing with this in the AutoCAD environment, that would do the trick as well. For now I made a spatial adjustment, and it works well enough. Looks like the ET GW function would be the easiest function for me since I already have it installed, guess I should've checked there first! :) – Martin May 20 '14 at 5:42

My first suggestion, if it is an option/available, would be to perform the rotation in AutoCAD (or have the author do it for you). Because of the potential variants on how things could have been drawn (blocks, xrefs, etc) rotating everything at once would be simplest there. The rotate tool allows you to rotate everything around a specified input point dynamically, with a snap, or a specified angle. Then you can convert to shapefile without having to worry about individually rotating and keeping aligned several pieces.

The next option would be the Rotate tool on the Editor toolbar. Select everything, hit that tool, and you can also rotate dynamically or using a specified angle by typing A. But rather than specifying a rotation point as in CAD, ArcGIS will rotate about the centroid of the group of selected objects (just as it would the centroid of an individual object). You can move this centroid control point (look for the x in the middle, hold ctrl and hover over the x until the cursor changes, then click to drag it), but the problem is it's going to start in a different location for every group. And if you've broken the dwg into multiple shapefiles, you can only be editing one at a time (feature classes in a geodatabase wouldn't have this issue). As a result, before doing any rotation editing you would need to create a reference point that you can snap the various group control points to so you end up rotating them all about the same point, otherwise you're going to throw the alignment off.

Other options include the Spatial Adjustment tool as PolyGeo suggested (again you may need to create a reference point/line for precise rotation and preserving alignment), and both ET GeoWizards and Hawth's Analysis Tools also have rotation tools.

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