TIN interpolation to construct DEM shows strange triangulation

Question

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:

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:

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:

Any clues on what can be the problem?

Gabriel De Luca · Answer

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.

TIN interpolation to construct DEM shows strange triangulation

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