I'm working with QGIS and I am trying to create a DEM starting from a DXF containing the grid of points located at 5m from each other. The following picture shows the points imported: enter image description here

I used a TIN interpolation and asked to obtain a raster with 5 m pixel size. The result obtained in the raster shows strange horizontal lines: enter image description here

I saved also the shapefile of the triangulation obtained but the resulting triangulation shows that overall it works well but every some rows, it create a dense row (it looks like a thick line but it is actually a bunch of lines), as shown in the following picture: enter image description here

Any clues on what can be the problem?

  • I would take a small subset of the data and triangulate it and examine the values of the points just to rule that possibility out.
    – Techie_Gus
    Aug 22, 2020 at 8:05

1 Answer 1


There is some problem in the angles optimization for the triangulation when it is based on a rectangular grid of points.

Use the GDAL Rasterize (vector to raster) algorithm.

Make sure that the extent of the output will be 2.5 meters outside the points to each side, to have the points at pixel centers.
I draw a rectangle polygon and buffer it with the half of the distance in the grid, to take the extents from the buffered layer.

For the output size, use georreferenced units, 5 meters at horizontal and vertical resolution.

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