[GIS] Importing DWG / DXF into QGIS

autocadexportqgis

I'm having some trouble converting a simple site schematic drawn in AutoCad into a shapefile for use in QGIS. A co-worker who works remotely has done the Autocad Drawings, and has exported as shapefiles, and sent me the .dwg, .dxf files, and when I load into qgis, they don't resemble the actual map drawn. It looks to me like maybe the autocad file might have been set up incorrectly? I've never worked with Autocad, wondering if someone may be able to shed some light on whats going wrong. I'll attach a pdf of the schematic he has done, and a screenshot of what appears in QGIS when I load his shp export, or dxf. i'll also attach the .dxf and .dwg file if someone wanted to have a look at them and see if there was something obviously wrong.

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The DXF consists of 2 parts.

1) The card frame / legend

2) The actual geodata

Your screenshot shows only the map frame (you can see at the coordinates) The data itself is in the north

The data itself is in 3 areas

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[GIS] Importing AutoCAD [DWG] drawings to QGIS [SHP] using right CRS settings

As @DPierce pointed out:

The coordinates in your drawing file are wrong. While the coordinate system is set correctly, the coordinates shown in the drawing are ~500 x ~200. You should be seeing coordinates closer to 300,000 x 60,000. QGIS is displaying it in the right place, because 0 x 0 for UTM 47N is in the Pacific to the West.

To import AutoCAD [DWG] to QGIS [SHP] my solution is the following, having AutoCAD Map 3D (ACM3D) as a requirement. This solution is tested with AutoCAD Map 3D 2014 and QGIS 1.8 . You also need some geospatial information (in my case a GPS track) which is georeferenced correctly and is in connection with the drawing you want to import into QGIS.

You have to convert this data into a fileformat that is readable by ACM3D. I've got a GPS-Track saved in GPX which is readable by QGIS. So I imported it into QGIS and exported it as a SHP-file. This SHP-file is readable by ACM3D.
Open your DWG drawing in ACM3D. Import the SHP-file with _MAPIMPORT. (To make the following process easier use _GEOGRAPHICLOCATION and use it to georeference your drawing elements. Now it's easier to find your drwaing elements and the imported SHP-file because you have a Bing Maps as basemap.) Now, use _ADETRANSFORM to, firstly, select the elements you want to transform and, secondly, to select two source and destination points. I selected the crossing of two streets in the drawing, then selected the appropriate point in the GPS track, then selected another crossing in the drawing and another appropriate point in the GPS track. Now, the drawing elements are transformed and should fit to the GPS track. (You can now fine tune the entire setup by redoing this operation.)
If you want to, you can _GEOGRAPHICLOCATION the entire drawing again to have the Bing Maps basemap fit accordingly.

Now, you can export the Drawing as SHP with _MAPEXPORT and import it into QGIS. The drawing is now at its correct location. I'm right now at optimizing this process that drawing elemts that belong to each other are exported as an entire feature... I will update this answer when I found some appropriate solution so that this answer can be called "completely".

Here are some links that helped a bit in finding my way through this Odyssee:

[GIS] Wrong scale when importing dxf into QGIS

Google satellite (EPSG:3857) is not a good idea. The units are metres, but only at the equator. The more to the North you go, the greater the difference gets.

Alternatively, you can use a custom CRS in transverse mercator projection, with latitude and longitude of origin (in degrees) at the point where your dxf file has its origin:

+proj=tmerc +lat_0=... +lon_0=... +x_0=0 +y_0=0 +k=1 +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs

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Related Solutions

[GIS] Importing AutoCAD [DWG] drawings to QGIS [SHP] using right CRS settings

[GIS] Wrong scale when importing dxf into QGIS

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