gathering different elevations for 3d buildings from dem

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 Castillojairo.castillo@calgary.caThe City of Calgary