The 3D buildings were extracted from LiDAR data collected by the City of Calgary but there were no attributes and the type of file of 3D buildings was a geodatabase. Based on what happened with flooding in 2013 the City of Calgary inspectors wanted to know in the event of future flooding, the lowest elevation of the houses or buildings to inspect right away to determine if the building is affected or not by the flooding. The elevations gathered were: 1. The lowest ground elevation of the building (x, y and z). 2. The highest ground elevation of the building (x, y and z). 3. The highest elevation of the building (x, y and z). These elevations were calculated for more than 400,000 buildings in the City of Calgary and the whole process to gather the elevations were processed from 2 different workbenches, one using the DEM to extract the ground elevations and the other workbench was using the real 3D building elevations to calculate the highest point from every single building.

1. Acquiring elevations for
3D Buildings
Jairo Castillo
The City of Calgary

2. 2013 Calgary Floods

3. 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.

4. How 3D Buildings were created?

5. LiDAR unclassified

6. LiDAR Classified

7. Buildings as dgn file

8. LiDAR and Buildings

9. 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)

10. It was a challenge to
process and find heights
of more than 418,000
individual buildings in
the City of Calgary

11. Points were generated
for every vertex on the
multipatch file

12. 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 >

13. Rooftop Elevation Workbench

14. Problem: The Minimum
Elevation of the
Building data does not
fit the surface of the
ground.

15. Part of the building is in
the ground.

16. Solution: 3D Buildings
have been transformed as
Footprint (2D) features
Key Transformer:
SurfaceFootprintReplacer

17. The footprint was
densified every metre
and the vertices were
extracted and
superimposed over the
DEM.

18. StatisticCalculator
extracts a min and max
value in Z for every
building

19. FeatureMerger selects
the minimum and
maximum elevation

20. The workbench creates
a point where the
ground has the
maximum elevation
along the footprint of
the building.

21. The workbench creates
a point where the
ground has the
minimum elevation
along the footprint of
the building.

22. Final Attribute table

23. Ground Elevation Workbench

24. Thank you!
Jairo Castillo
jairo.castillo@calgary.ca
The City of Calgary