Transcript LiDAR Damage Assessment for Disaster Relief Efforts in Urban Areas Geospatial World Forum – Crisis Management using 3D Rotterdam, 13 – 16 May,

LiDAR Damage Assessment for
Disaster Relief Efforts in Urban Areas
Geospatial World Forum – Crisis Management using 3D
Rotterdam, 13 – 16 May, 2013
Susan Parks, Ben D. Kamphaus & Thomas Bahr*
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Background Information
> A magnitude 7.0 earthquake struck
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Haiti on January 12, 2010.
Quake epicenter was 15 miles
WSW of Port-Au-Prince
(18.443°N, 72.571°W).
212,000 killed
300,000 injured
1.2 million displaced
Over 30 % of the buildings in
Port-au-Prince were destroyed
or damaged.
Imagery and LiDAR data courtesy of the RIT Haiti Mission for
the World Bank (January 21-27, 2010).
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Objectives and Resources
Objectives
> Inventory buildings and
assess building damage.
> Locate refugees in need of aid.
> Locate areas to land ground teams.
> Locate ways to route ground teams
to refugee camps.
Resources
> DigitalGlobe Worldview-2 Scene
from after event.
> LiDAR coverage of Port-au-Prince
from RIT/World Bank project.
> ENVI, ENVI LiDAR, and ArcGIS®
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Analyst Role
LiDAR
Processing
Spectral
Analysis
Network
Analysis
> ENVI LiDAR: Produces layers of relevance such as DSM, DTM, and building
footprints and roof shape polygons.
> ENVI: DEM processing is performed to calculate the heights of above ground
features and separate roads from structures and debris.
> ENVI: Blue tarp signature is used to extract blue tarp locations from the scene
to locate refugees.
> ArcGIS: Density maps highlight locations where refugees are located.
> ENVI: Road networks are extracted from LiDAR data and manually cleaned up.
> ArcGIS: Road networks are imported to a network dataset. Obstructions from
ENVI are used as barrier inputs for ground team routing.
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LiDAR Processing
Tasks
> Use LiDAR data
to map road networks.
> Catalogue standing buildings
and their extant shapes.
> Assess the debris distribution.
Methodology
> Feature extraction, orthophoto and
DEM generation from LiDAR data.
> Examination of the results with a
3D Viewer.
> Usage of an object-based feature
extraction tool to extract the road
networks.
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LiDAR Processing Steps
> Use ENVI LiDAR to process LiDAR data to extract building footprint and
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roof shape features, and create an orthophoto, DSM, and DTM.
Examine the results with the 3D Viewer in ENVI LiDAR.
Use ENVI to extract feature heights layer from DSM and DTM.
Map road networks and debris networks from LiDAR feature heights layer
through threshold classification.
Generalize debris and road networks to appropriate vector file types
and export to an ArcGIS geodatabase.
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Extracting Debris and the Road Network
DSM
–
DTM
Equals the vertical
obstruction layer.
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Threshold Classification Results
Road surface
Debris
Buildings and taller structures
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Analyst Role
LiDAR
Processing
Spectral
Analysis
Network
Analysis
> ENVI LiDAR: Produces layers of relevance such as DSM, DTM, and building
footprints and roof shape polygons.
> ENVI: DEM processing is performed to calculate the heights of above ground
features and separate roads from structures and debris.
> ENVI: Blue tarp signature is used to extract blue tarp locations from the scene
to locate refugees.
> ArcGIS: Density maps highlight locations where refugees are located.
> ENVI: Road networks are extracted from LiDAR data and manually cleaned up.
> ArcGIS: Road networks are imported to a network dataset. Obstructions from
ENVI are used as barrier inputs for ground team routing.
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Blue Tarp Analysis
> Blue tarps concentrations can be used to identify the locations
of displaced people.
> Blue tarps are also spectrally distinct.
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Routing Priority Determination
> Now that we have extracted blue tarps,
we can create a point density map using
ArcGIS Spatial Analyst to determine where
concentrations of refugees are.
> We will use these hot spots to select route
stops in the final ground team routing.
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Analyst Role
LiDAR
Processing
Spectral
Analysis
Network
Analysis
> ENVI LiDAR: Produces layers of relevance such as DSM, DTM, and building
footprints and roof shape polygons.
> ENVI: DEM processing is performed to calculate the heights of above ground
features and separate roads from structures and debris.
> ENVI: Blue tarp signature is used to extract blue tarp locations from the scene
to locate refugees.
> ArcGIS: Density maps highlight locations where refugees are located.
> ENVI: Road networks are extracted from LiDAR data and manually cleaned up.
> ArcGIS: Road networks are imported to a network dataset. Obstructions from
ENVI are used as barrier inputs for ground team routing.
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Road Obstruction and Ground Team Routing
> When disasters occur, not all road networks remain navigable.
> How do we tell which ones are usable?
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Ground Team Routing
> Image data and
processed LiDAR data is
fused for enhanced road
extraction.
> Road network is input
into ArcMap.
> ArcGIS Network Analyst
is used to solve routing
problems in the
resulting network.
> Layers extracted from
ENVI LiDAR and ArcGIS
Spatial Analyst can
provide additional
routing context.
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Debris Layer Calculation
> The debris classification layer
from the threshold is separated
from the other layers.
> The debris raster is then
generalized and converted
to a polygon class.
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Debris Density Calculation
> Debris polygons are converted to
attribute rich polygon centroids.
> These centroids are then used to
calculate a point density layer,
weighted by area (larger debris
contributes more to density).
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Debris Density Calculation
> The point density layer is then
thresholded and exported to two
different polygon classes.
> High values are considered
complete barriers.
> Medium values increase the
network traversal cost.
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Synthesis
LiDAR
Processing
Spectral
Analysis
Network
Analysis
> ENVI LiDAR: Produces layers of relevance such as DSM, DTM, and building
footprints and roof shape polygons.
> ENVI: DEM processing is performed to calculate the heights of above ground
features and separate roads from structures and debris.
> ENVI: Blue tarp signature is used to extract blue tarp locations from the scene to
locate refugees.
> ArcGIS: Density maps highlight locations where refugees are located.
> ENVI: Road networks are extracted from LiDAR data and manually cleaned up.
> ArcGIS: Road networks are imported to a network dataset. Obstructions from
ENVI are used as barrier inputs for ground team routing.
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Network Analyst Techniques for Routing
> Once the dense debris is
added to the network
analysis layer as a polygon
barrier, routes which do not
cross dense debris can be
obtained.
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Network Analyst Techniques for Routing
> If multiple helicopter landing
zones are being considered,
routes from and to different
refugee camps can be
evaluated using the closest
facility tool in the ArcGIS
Network Analyst.
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Summary
> LiDAR is becoming a critical component of disaster relief planning.
> Imagery combined with LiDAR data can be used as inputs to
support emergency response to crises like earthquakes.
> Inputs from LiDAR processed with ENVI LiDAR can be used in
ArcGIS Network Analyst to provide real world constraints
when solving mission routing problems.
> LiDAR can help emergency responders inventory buildings,
land ground teams, find passable routes, and otherwise
support crisis response efforts.
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Questions & Discussion
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