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I would like to do what's needed in a GIS (GRASS, QGIS, etc) alone, no other converters-only.

The process is to read the dwg files that would be located in a folder and read them as shp and perform calculations like snapping later or using a geodatabase to store the files and later export them as shp.

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ogr2ogr supports DWG to some extent: http://www.gdal.org/drv_dwg.html

So should be as easy as:

ogr2ogr shapefile.shp cad_file.dwg

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    And what is this? Just python with the ogr2ogr module? Clarify. What parameters takes and so. Thanks – user10138366 Jul 27 '18 at 10:42
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    ogr2ogr is a command line utility. I don't know if your on window or linux. But the easiest way to use it on windows is to use the OSGeo4W installer trac.osgeo.org/osgeo4w , then though the OSGeo4W Shell you can type in the provided command. – HeikkiVesanto Jul 27 '18 at 10:48
  • In the shp part u say the name it is going to have after conversion from dwg, and in the dwg part you say the file you want to convert? – user10138366 Jul 27 '18 at 11:13
  • Yep. That is correct. – HeikkiVesanto Jul 27 '18 at 11:29
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What's wrong with Project -> DWG/DXF import in QGis?

  • i want to open in a loop all the files and then do calculations like snapping, etc . how do you suggest to do it like this? i tried uding that but it just opens the file one by one and it doesn't convert it to shp. i think – user10138366 Jul 27 '18 at 11:11
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    That's an important information, that you want to do batch processing. From the GRASS-tools, try v.in.dxf, maybe that helps. When incorporated into a graphical model, you may even run the whole process as a batch process. – Erik Jul 27 '18 at 11:30
  • Can it process dwg or only dxf? – user10138366 Jul 27 '18 at 11:47
  • Interface suggests it can process both. You'll have to try. – Erik Jul 27 '18 at 12:22
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I have done the conversion CAD -> GIS several times, unfortunately, to your request, I performed with the usage of ArcGIS. However, I would like to highlight, that there is always a part left for a manual work due to the difference between GIS and CAD and humans factor in it. At least in my case, I worked with data that was acquired through the surveying.

The last time I did it, I have used a feature from ArcGIS toolbox, known as

ArcToolbox > Conversion Tools > To Geodatabase (CAD to Geodatabase)

I had lots of buildings, therefore some of them were not converted into proper polygons what they should be. Because of that, I used a function to transform unclosed polygons, i.e. polylines into polygons.

ArcToolbox > Data Management Tools > Features > Feature to Polygon

But you have to be careful since some of the polygons cannot be produced because of the distance between starting and ending point of the polyline.

Additionally, I can refer you to Converting polyline to polygon in ArcGIS Desktop for floodplain map? and How to close polylines that mark shape of cirque glaciers?.

With the development of QGIS, I can recommend the most common way, which was mentioned by Erik, to use

Layer > Add Layer > Add Vector Layer > AutoCAD DXF (*.dxf, *.DXF)

Alternatively, there is a bunch of plugins in QGIS, e.g. CADDigitize, Another DXF Importer / DXF2Shape Converter, CadInput etc. Can refer you to DXF Import QGIS: Text Components.

Not sure about ogr2ogr. Perhaps HeikkiVesanto is correct.

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