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dataprocessing_citygml.md

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Dataprocessing CityGML -> PolyhedralSurfaceZ

pg2b3dm takes as input triangulated PolyhedralSurfaceZ geometries in PostGIS. In this document a sample workflow is described for processing CityGML files using FME, GDAL and PostGIS.

Sample input files: https://www.opengeodata.nrw.de/produkte/geobasis/3dg/lod2_gml/

For example, download https://www.opengeodata.nrw.de/produkte/geobasis/3dg/lod2_gml/lod2_gml/LoD2_280_5657_1_NW.gml

FME

fme_workbench

In FME the CityGML file is imported and the buildings are exported as triangulated shapefiles using the following steps:

  1. Import CityGML open the file using the CityGML reader and select the parts from the CityGML you want to use.
  2. Select the Solids using the GeometryFilter.
  3. Triangulate the solids using the Triangulator, pg2b3dm needs PolyhedralSurfaceZ with 4 coordinates.
  4. Export as SHP using the Esri shapefile writer.

A sample workbench is included, see dataprocessing/dataprocessing_citygml.fmw

The model can run from command line:

$  "D:\Program Files\FME\fme.exe" citygml2esrishape.fmw --DestDataset_ESRISHAPE "multipatch.shp" --SourceDataset_CITYGML_3 "LoD2_280_5657_1_NW.gml" --FEATURE_TYPES ""
Reading.......200....400.....600....800.....1000....1200...
Emptying factory pipeline...
Translation was SUCCESSFUL

Output is multipatch.shp

GDAL

  1. Import SHP as PolyhedralSurface using ogr2ogr. -dim 3 makes sure to use the x, y and z information -nlt POLYHEDRALSURFACEZ sets the correct geometry
$ ogr2ogr -f "PostgreSQL" "PG:host=server user=username dbname=database" multipatch.shp -nln schema.tablename -dim 3 -nlt POLYHEDRALSURFACEZ

PostGIS

  1. Delete geometry collections containing geometries with more or less than 4 vertices (triangles).
psql> DELETE FROM schema.tablename WHERE (ST_Npoints(wkb_geometry)::float/ST_NumGeometries(wkb_geometry)::float) != 4;
  1. Add id and color columns, both in text format.
psql> ALTER TABLE schema.tablename ADD COLUMN id text;
psql> ALTER TABLE schema.tablename ADD COLUMN color text;
  1. Populate the added columns.
psql> UPDATE schema.tablename SET id = ogc_fid;
psql> UPDATE schema.tablename SET color = '#f5f5f5';

Now it's possible to run pg2b3dm!

Result looks like: Duisburg_pg2b3dm

Live demo: https://geodan.github.io/pg2b3dm/sample_data/duisburg/mapbox/#15.62/51.430166/6.782675/0/45