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I would like to georeference a DWG layer using QGIS 3.

I have imported the DWG layer saved by Microsoft Office Visio Professional. After import I have a nice lookup like below.

enter image description here

The problem is, that I would like to plot this layer with an existing GeoTiff raster layer in QGIS.

enter image description here

I found some hints:

and most of them indicate firstly the conversion to DXF or even SHP and next georeferencing.

I am not happy with that solution, because this DWG layer is good-looking and keeps all shapes and colourations the same as they appear in Visio.

Is there any way to georeference them similarly to the raster georeference in QGIS, where I can pick up some points from the maps and assign them to my DWG layer?

I am interested in the vector georeferencing in this case. I checked the Vector bender plugin, but it doesn't work this way.

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    Best way to "georeference" any CAD drawing is to create the drawing at the correct place in the canvas from the start. Decide on a m-based CRS, then move the drawing to the correct place and import it into QGIS using the same CRS.
    – Erik
    Aug 12, 2020 at 10:17
  • I am using Visio and saving the file as DWG format. What did you mean "Create drawing at the correct place in the canvas?" Shall I draw everything in QGIS from the start?
    – MKR
    Aug 12, 2020 at 10:42
  • Either use QGIS directly, or expand the canvas in Visio so you can draw in the correct location - provided Visio lets you use m as a unit.
    – Erik
    Aug 12, 2020 at 11:10
  • It looks like there is no option to draw shapes by using coordinates in Visio. So it means, that I have to redraw these shapes in QGIS right?
    – MKR
    Aug 12, 2020 at 11:13
  • If you want to do it correctly, and the shapes are not that complex, yes. I wonder how you were able to create them in the first place in Visio, since they seem to be oriented around the local features?
    – Erik
    Aug 12, 2020 at 11:25

2 Answers 2

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There are at least 2 easy ways to do it:

  1. Transform Vectr Layer with SAGA
  2. manual

The first one can be done quickly just after setting coordinates and alternatively the scale factor. We have to remember, that in this case the dX and dY inputs are important, NOT X,Y as mentioned in the link below! (I fixed it in the comment).

GRASS v.transform tool producing no results QGIS

enter image description here

After running the algorithm you should see your drawing closer to the location, which you picked up. For the UK conditions, the handiest is gridreferencefinder.com

The second - manual way is also easy. If you are using some coordinate system, you must know, that your layer is to be placed at the very beginning of the cartesian coordinate system. It means, that for Pseudo-Mercator it will be Lat 0 Lon 0, or for British National Grid (my example) something about Lat 49,5 Lon -7,5. Having it in mind, you can just provide some XYZ map canvas, and next:

  • toggle selection bar for your vector layer
  • launch advanced digitizing tool (right-click on the editing mode pencil)
  • select your layer (area selection) seeing it whole in yellow
  • use the "move feature" tool gluing your shape to the cursor and dragging it shortly towards the target destination.

The details of these 2 ways are in the link below:

http://www.mkrgeo-blog.com/good-solution-to-georeferencing-the-autocad-dwg-drawing-in-qgis-3x/

enter image description here

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Qgis now has vector georeferencing. Similar to raster georeferencing, that may be a simpler option and more intuitive.

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  • Good to know, thanks
    – MKR
    Apr 26 at 13:39

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