contourdemelevationgrass
I have two shape files containing height information of a certain area and I need to create a raster DEM with GRASS using them.
What would be the best technique to generate raster DEM with these two types of data?
Do i need to generate some spot heights from contours and then integerate with existing spot heights for DEM generation or any other method?
First of all, if you want to work with heights, normalize the LiDAR point cloud.
You have a dense point cloud (4 pts/m²) and also high resolution aerial photos, hence, as you said getting the outside roof perimeter is not an issue. Therefore, assuming you'll manage to have a shapefile with the outer roof boundaries, use it to horizontally clip the point cloud and so, isolating building-only points. See here, for example.
Then, from each new .las file generated in previous step retrieve the vertical profile to identify how many surfaces there are in the scene. Tweak the class interval in the histogram, in order to identify all major surfaces. Get the height breaks to be used in the next step.
Clip the point clouds vertically in order to isolate points within same vertical surface (for example, with Fusion use ClipData with switches zmin and zmax). Then, generate individual Digital Surface Models (DSMs; examples 1 and 2) and convert the outputs to polygons using tools of type Raster to Polygon. The polygons will have the surface height in the TOC.
Try to use a programming environment to automate all the processing steps (example).
I downloaded your contour geopackage. Open it with QGIS, right click the layer -> Layer CRS -> Set Layer CRS -> Search for "3912" -> OK
Your contour lines should be where you want them
Best Answer
I would highly recommend going through the Contour lines to DEM tutorial, available from GRASS wiki. Essentially, they describe different interpolation methods used to produce a DEM. Avoid IDW interpolation using contour lines (i.e. described in one segment of the tutorial) since this is an inappropriate use of the interpolation method. The GRASS module
r.surf.contouris probably what you are looking for--more details about the module available here. Their tutorial shows a pretty good interpolated DEM from rasterized contour lines: