gathering different elevations for 3d buildings from dem
TRANSCRIPT
Acquiring elevations for 3D Buildings
Jairo CastilloThe City of Calgary
2013 Calgary Floods
In case of future flooding, the inspector can access building information that identifies where the minimum elevation of the building is to check if the building has been affected. This is important as inspectors often only view the front of residences and buildings.
How 3D Buildings were created?
LiDAR unclassified
LiDAR Classified
Buildings as dgn file
LiDAR and Buildings
3D Buildings have unique Structure ID attributes and the project was to calculate three Elevations per building (Rooftop, Ground Min Elev, and Ground Max Elev)
It was a challenge to process and find heights of more than 418,000 individual buildings in the City of Calgary
Points were generated for every vertex on the multipatch file
Multipatch Shapefile: Consists of a number of surface patches.
“ESRI Shapefile Technical Description” July 1998 . ESRI <http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf >
Rooftop Elevation Workbench
Problem: The Minimum Elevation of the Building data does not fit the surface of the ground.
Part of the building is in the ground.
Ground
Solution: 3D Buildings have been transformed as Footprint (2D) featuresKey Transformer: SurfaceFootprintReplacer
The footprint was densified every metre and the vertices were extracted and superimposed over the DEM.
StatisticCalculator extracts a min and max value in Z for every building
FeatureMerger selects the minimum and maximum elevation
The workbench creates a point where the ground has the maximum elevation along the footprint of the building.
The workbench creates a point where the ground has the minimum elevation along the footprint of the building.
Final Attribute table
Ground Elevation Workbench
Thank you!Jairo [email protected] City of Calgary