LiDAR Damage Assessment for Disaster Relief Efforts in Urban AreasGeospatial 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 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

> 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.

Spectral Analysis

> 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.

Network Analysis

> 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 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

LiDAR Damage Assessment for Disaster Relief Efforts in Urban Areas 9

DSM – DTM

Equals the vertical obstruction layer.

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Threshold Classification Results

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Road surfaceDebrisBuildings and taller structures

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Analyst Role

LiDAR Processing

> 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.

Spectral Analysis

> 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.

Network Analysis

> 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

> 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.

Spectral Analysis

> 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.

Network Analysis

> 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 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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Debris Density Calculation

Synthesis

LiDAR Processing

> 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.

Spectral Analysis

> 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.

Network Analysis

> 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 ArcGISNetwork 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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