1. California Institute of Technology
Monitoring Urban Changes from Digital Surface Models:
Generating DSM using Worldview Imagery and COSI-Corr Processing vs. Airborne LiDAR Acquisitions
Sebastien Leprince
Francois Ayoub
Office:
Cell:
California Institute of Technology
Patent U.S. 8,121,433 B2
California Institute of Technology
imaginlabs.com

2. Case Study: City of Christchurch, NZ
Data:
Worldview panchromatic stereo-pairs (courtesy of DigitalGlobe):
- Acquired in September 2009
- Acquired in August 2011
LiDAR acquisitions (via GNS Science, NZ):
- 1m gridded LiDAR acquired mid-2010
- 1m gridded LiDAR acquired late-2011
Goal: Comparing the digital surface models produced using COSI-Corr on pairs of 0.5m stereo Worldview images with state-of-the-art airborne LiDAR acquisitions.
Applications: City planning, urbanism, insurance, rapid response to catastrophic events (e.g., earthquakes, liquefactions).

3. Eastern part of downtown Christchurch, NZ, zoom on a small 650x350m area
2009 Worldview DSM generated with COSI-Corr
1m GSD
2011 Worldview DSM generated with COSI-Corr
1m GSD
COSI-Corr DSM extraction using Worldview stereo imagery
competes with LiDAR
2010 LiDAR DSM, 1m GSD
2011 LiDAR DSM, 1m GSD

4. 2010 LiDAR DSM
1m GSD
2011 LiDAR DSM
1m GSD

5. 2009 Worldview DSM generated with COSI-Corr 1m GSD

6. Comparison of height profiles on buildings (2011 data)
All heights in meters
Dotted Profiles = COSI-Corr + Worldview DSM
Solid Profiles = LiDAR

7. Comparison of height profiles on buildings (2011 data)
All heights in meters
Dotted Profiles = COSI-Corr + Worldview DSM
Solid Profiles = LiDAR

8. Comparison of height profiles on buildings (2011 data)
All heights in meters
Dotted Profiles = COSI-Corr + Worldview DSM
Solid Profiles = LiDAR

9. Looking at Building Height Change
Blue areas are negative changes in height in excess of 3m (building destruction)
Red areas are positive changes in height in excess of 3m (building construction)
Building destruction after the Feb Christchurch earthquake
Building construction after the Feb Christchurch earthquake
Building destruction after the Sept Canterbury earthquake?
2009/2011 Difference between Worldview DEM generated by COSI-Corr
2010/2011 Difference between Worldview DEM generated by COSI-Corr
Building construction after the Sept Canterbury earthquake

10. Conclusions Can compete with LiDAR
Cheaper (~$100/km^2 vs. ~$1000/km^2)
More responsive (no need of flight autorization)
Global ….