I have acquired LoD2 building models in the 3DShape format (Polygon ZM). This LoD2 data needs to be prepared for a R-script of solar irradiation calculations on roof surfaces, but which can only process raster data.

Is there a way to 'rasterize' the 3D Shapefile into a digital surface model (DSM)?

Lets say for example, that I want a spatial resolution of 0.25 x 0.25 meters for each raster cell, than the height of the highest feature (i.e. the roof polygon) should be extracted from the LoD2 data at the location where it intersects with the center of each raster cell. So that in the end I get a 'DSM' of the shapefile.

Sample LoD2 data can be downloaded here: http://vermessung.bayern.de/file/zip/6817/LoD2_3DShape.zip

I have found nothing in the ArcGIS help resource center, and no GRASS function either. ArcGIS, QGIS, GRASS and R are available to me.

If you know a alternative way to calculate solar irradiation on a 3DShape surface, you would be of help as well. I have irradiation measurements for an fixed normal (=horizontal) surface in the area. What my R script does is it calculates the effect of the rooftop geometry and the shadows of nearby objects (= other buildings) on the measured irradiation at 1 hour time-steps over an entire year and then summarizes the W/m² to evaluate which rooftops get the most sunlight.

  • See here for solar radiation calculations in Arcmap. See here for converting your features to raster in Arcmap. – Barbarossa Jul 20 '15 at 15:50
  • @Barbarossa: Thank you for your comment. In response to your suggestion to use Feature to Raster (Conversion toolbox): The field Shape.Z can only be used in point or multipoint feature conversion. Do you think there is a way to transform the roof polygons of the LoD2 models to multipoint shapefiles (with i.e. four points/m²? – Achu Mani Jul 21 '15 at 13:26

Found a solution using ArcGIS:

I use the tool

3D Analyst >> Data Management >> TIN >> 'create TIN'

to create a TIN file with the setting 'SF Type: hardclip'.

Then I use the tool

3D Analyst >> Conversion >> From TIN >> 'TIN to Raster'

to create the raster DEM. Because of the size of the buildings that I want to identify (singe residential houses), I used 'CELLSIZE 0.25' to create smooth edges.

I guess the same can be done with GRASS, which is what I'll try next.

  • Did you do this with GRASS? I'm curious what tools you used. – cndnflyr Oct 28 '15 at 16:07
  • @cndnflyr not yet, sorry. I'm did this for my thesis and didnt even have the time to see if the nescecary utilities (3DShape to TIn and TIN to Raster) are available in GRASS. Once I have handed in my thesis, I will have time to explore more open source alternatives. I loath using ArcGIS. – Achu Mani Oct 29 '15 at 17:29

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