[Qgis-user] Georeferencing dxf file in QGIS

[Richard Greenwood]

You can just use the QGIS *Move Feature* tool, possibly in conjunction with
the *Rotate Feature* and/or *Scale Feature* tools in the advanced
digitizing toolbar.

   1. Assign a coordinate system to the DXF layer. If you don't know the
   coordinate system, or if the DXF file doesn't have one, assign the
   coordinate system of your reference layer (your aerial photography)
   2. Make your DXF file editable. Depending on how you imported it you may
   be able to make it editable, or you may need to copy all of the features to
   an editable work layer.
   3. Select all of the features, pick the *Move Feature* tool, pick a
   source point on a corner of the building, pick a destination point on the
   corresponding corner in your reference layer. (this takes some serious
   panning and zooming!)
   4. With all of the features still selected, pick the *Rotate Feature* tool,
   while holding the Control key click the building corner to fix the rotation
   base point, then click two more points to define the rotation angle.
   5. You may need to scale it e.g. convert feet to meters. If so,
pick the *Scale
   Feature* tool, hold the Control key and click a base point, then two
   more points to resize all of the features.

The move, rotate and scale steps are performing an affine transformation
which should provide reasonable results over small areas if both the DXF
and reference layer are in projected coordinate systems, ideally local
projected coordinate systems like State Plane or UTM, and not Web Mercator.






On Tue, May 14, 2024 at 3:00 PM Linda Boisvert via QGIS-User <
qgis-user at lists.osgeo.org> wrote:

> Hello,
>
> I have been trying to georeference a dxf file created by a solar design
> software.
>
> I can import the file without issues but the design sits in the middle of
> the Pacific Ocean. I have georeferenced rasters before but I can't get this
> dxf file to budge.
>
> I have tried many of the suggestions I have found online for
> georeferencing the dxf file.
>
> I have tried to move the design using QAD and QAD did not find objects
> when I tried to select the design or any single line.
>
> I imported the file into LibreCAD and the file worked fine in that
> software.
>
> I imported the file into ArcGIS and I could not see the lines of the dxf
> file.
>
> I have attached a test dxf if someone wants to try it out and find a
> solution. The building is the Eugene Brucker Education Center 4100 Normal
> Street San Diego, CA 92103.
>
> Does anyone have any suggestions for georeferencing this file or any idea
> what the issue may be?
>
>
>
>
> --
> Sincerely,
> Linda Boisvert
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-- 
Richard W. Greenwood
www.greenwoodmap.com
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