Exporting contour lines from CAD to GIS

Question

I've been using GIS softwares in the past few years by I'm new using AutoCAD.

Well, I have contour lines in AutoCAD and I want to export it into QGIS (I also have access to ArcMAP).

I saved as .dxf (AutoCAD 2007/LT 2007 DXF) in AutoCAD. It opened fine in QGIS. However, it seems that didn't export the contour values (Take a look in the attribute table).

Am I missing some step?

Answer 1

If it is 3D DXF, follow the steps:

1. import the dxf in QGIS (DRAG & DROP or CTRL + V);
2. save as vectors (as the right mouse button);
3. add new field Z (integer);
4. Browser Panel to create a new database spatialite;
5. DBManager to import the shape in the newly created database;
6. run the update query;

step 1

step 2

step 3 - add new field Z

step 5 -DB Manager

step 6 - query

Answer 2

@pigreco's answer should work.

But here a simpler solution without the spatialite process (step 1 to 2 are the same).

1. Load your .dxf and export (save as...) as shapefile (or spatialite / postgis).

2. On the new layer, use the Field Calculator (accessible from the main toolbar or from the attribute table).

   

3. Setup the new column (name and type, virtual or not depending on your needs) and use the expression :

   z(point_n($geometry, 1))

As @pigreco said, your dxf needs to be 3D.

Answer 3

I was having a similar issue. From CAD I extracted major and minor contours (command: _AeccSurfaceExtractObjects). From there, select all the 3Dpolylines generated from the extraction, and export to shapefile format (command: mapexport). In the export dialog box, select "Line" for object type, and "Select Manually". To get the Z-values, select the "Data" tab in the dialog box, and hit the "Select Attributes" button. From there, select the object property which contains the Z-values. This shapefile can then be directly imported to QGIS as a vector layer.

Hope this helps someone!