Extracting xyz data from .dxf after conversion to shapefile in QGIS

Question

I have both a .dwg and derived .dxf data set originally generated in AutoCAD Civil 3D. It appears as a series of triangles which cannot be exploded but each individual triangle does have xyz coordinates attributed to it.

When imported into QGIS the attribute table does not contain the xyz data, only Layer, SubClasses, Linetype and EntityHandle. Each of these EntityHandle elements when viewed in Draftsight by using the GetProperties command does have a list of xyz coordinates attributed to it.

Ideally I'd like to produce a shaded relief contour map of the dataset but without access to the individual xyz data, I'm just going around in circles. Am I approaching this in the wrong way or is there an easier way to extract the xyz data to allow the contour generation task to be completed quickly?

Answer 1

I have tried this many times but never found a quick way. My workflow: 1. Import DXF in QGIS, check CRS is correct 2. Vector > Tools > Extract Vertices 3. In the new Vertices layer, open attribute table, create new calculated column (z) with z($geometry) to get the elevations 4. Generate a raster (DEM) using one of the interpolation methods (Grid, TIN, IDW...) 5. Apply colour render, extract contours, etc. I'm sure there is an easier / more straightforward way to achieve this. Happy to hear anyone else's solution!