Workflow to get DWG or DXF into QGIS

[ia...@jcis.net.au]

As a consultant we all hate clients . My particular hate at the moment is getting files from clients originating in either AutoCAD or Revit in DXF or DWG format which are supposedly projected to open in QGIS.

As drawings typically they use a local coordinate system related to a point 0,0,0 within the drawing or model. So to use them in a GIS they need to be associated with a projection and then exported from their program in a format that QGIS can read. 

Does anyone have a workflow that I could use to explain how to do this. I know nothing about Revit and not that much about AutoCAD.

The aim is to drop our client's plans into a GIS so we can figure out how much archaeology and heritage they will impact.

Cheers - Iain

[Benjamin Crockett]

Instead of expelling all this hate Iain, have you tried giving some data standards to you hated clients? Once data is recorded at 0,0,0, I am afraid you have to locate it a new. 

Shouldn't be too difficult to do, but would be time consuming. Consulting may not be the game for you, am interested if anyone else has this perspective however? It is only Monday, may be a long week. 

BC. 

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[Luke Kirkwood]

Hi Iain,

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

The path you travel is one fraught with many pitfalls. Good luck.

Also, you’d be surprised how many of these clients have KMLs of their DXFs. Never hurts to ask/demand. I always do.

Cheers

Luke

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[Mark Arnup]

With the use today of GNSS survey gear using RTK-COORS networks, the days of AutoCAD files not being in a known CRS are really over.

If your cilants are not able supply you with AutoCAD files in a known CRS, then it should be up to them to deal with!

Mark Arnup
62 Reef St
Wedderburn 3518
Ph: (03) 5494 3358
Mob: 0417 510 853

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[Juan Fernando Berrío]

An example of a file format that you can use as a bridge between AutoCAD, and many other CAD applications in general, and QGIS is DXF ASCII 2010.  

DXF is sort of a universal file format designed for this purpose, but you can't forget that there are many versions of it - 2010 always works for me. 

Regarding being frustrated with the client, and how to design a data workflow that works for both of you... that is more of a general consulting question rather than a QGIS question.  Clients are valuable for many of us - if you don't see it that way, maybe you'd benefit from taking a short break and thinking if the job you're doing is fulfilling enough to keep doing it for a long time.  On occasions,  it may end up being a bit frustrating working with some other person if you don't understand each other's expectations well.  Maybe your counterpart knows very little about GIS, surveying and map projections, and expects you to 'solve all of their problems' regarding surveying and mapping.  Sitting down with them and explaining the data requirements or minimum needs for you to be able to do the mapping may be able to solve it all.  As some people call it, you can "educate your client".  Or maybe you can recommend a good surveyor that can help them and help you by doing the field work and providing data in a suitable format? 

Hope it helps. 

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[ia...@jcis.net.au]

Sorry I was being a bit flippant when I said we consultants all hate our clients. 

This issue however is really to do with getting the client's designers to convert their unprojected models (which are made on a local grid) to projected ones. Reviewing some of the options it seems the solution is at the supply end ie with the designers and architects as it is hard to georeference the models and plans once they come to us as there are often no features to use. Maybe if we talk kml as Luke suggests they might respond better than talking shapefile. We do have it in the contract that the client will provide the drawings in shapefile format but that doesn't seem to work all that well. 

With surveyors it's another question.

Cheers Iain 

[Emma Hain]

Hi Iain

Start with this link and see where it takes them: Autodesk GIS Coordinate System

If they push back and won't do it, then they are not fulfilling the scope. The data is not complete for use. It is up to them to provide you with workable data. Just say no and don't work out their problem. Move onto your next problem. 

Good luck

Em

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[ia...@jcis.net.au]

Thanks Em,  the Autodesk information is most helpful. 

What we are careful in doing is to cover potential issues by qualifying our report to cover the mapping issues from the client. BTW we do something similar with our Georeferenced plans popinting out the obvious accuracy issues in georeferencing historical plans.

Cheers Iain

[Luke Kirkwood]

Hi Iain,

While looking for something else, I came across this great little tutorial for georeferencing Revit, AutoCad's spiritual successor in the construction industry. Most companies appear to have made the switch to Revit these days, but even so Revit is very similar to AutoCad so the principles will be the same.

https://parametricmonkey.com/2020/04/08/geo-referencing-revit-models/

Cheers

Luke

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