Using Laser Scanning and Open Source GIS to Analyze Trends and Impacts of Topographic Change

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Using Laser Scanning and Open Source GIS to
Analyze Trends and Impacts of Topographic Change

• Helena Mitasova, Margery Overton, Richard
  McLaughlin
• North Carolina State University
• Russell S. Harmon
• Army Research Laboratory, Army Research Office
• with contributions by NCSU graduate students
• JJ Recalde, E. Hardin, O.M. Kurum

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Open source GIS GRASS6.3 http//grass.osgeo.org
Developed by US Army CERL 1982-1993 GPL since
1999, current development coordinated from
Trento, Italy General purpose GIS 2D/3D raster
and vector data management, analysis, modeling,
visualization for Linux, Mac and MSWindows DBMS
attribute and SQL support WebGIS coupling Many
modules provide powerful tools for lidar data and
DEM analysis
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Coastal and inland impacts

• Costal terrain dynamics
• sea level rise, waves, wind
• development
• North Carolina barrier islands 12 years of
  lidar data analysis

Cape fear dynamics 1998-2004

• Inland terrain change
• anthropogenic development
• impact on runoff, sediment
• sustainable land design with Tangible GIS -
  laboratory laser

Exploring impact of a dam on runoff
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Spatial coastal change indicators

• derived from integrated time series of diverse
  lidar surveys 2m res. DEMs
• represent spatial pattern of coastal terrain
  evolution based on per grid cell statistics
• Mitasova, Overton, Recalde, Bernstein,
• and Freeman, to appear in Journal of Coastal
  Research

year at minimum and maximum elevation draped over
2005 DEM
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Spatial coastal change indicators
Beach and dunes near Oregon Inlet

• core surface
• below which elevation never decreased
• outer envelope
• above which elevation never increased
• Some new homes built with exception from
  regulations do not have any core surface?

Beach and homes in Rodanthe
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Surface evolution as volume
Shorelines
1997 1998 1999 2001 2003 2004
New approach Evolution of terrain surface is
represented as a volume with time used for 3rd
dimension. Evolution of a contour is then
represented as an isosurface.
Isosurface representing shorelines 1997-2005
2005 2003 2001 1999 1997
Time year
isosurface
Ym
Xm
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Surface evolution as volume
stable back-shore beach
z1.5m
2005 2003 2001 1999 1997
dynamic shoreline
z0.3m
sand disposal
2005 2003 2001 1999 1997
Time year
Ym
0 200m
Xm
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Surface evolution as volume
highly dynamic ridges of foredunes
stable dune peaks
z7.6m
2005 2003 2001 1999 1997
z4.6m
2005 dune rebuilt 2003 dune overwash
2005 2003 2001 1999 1997
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Anthropogenic terrain change
Problems sediment deposition, road
flooding Design new land management alternatives
in 3D space and evaluate their impacts tedious
task on 2D screen
1993 photogrammetric DEM
Sediment pollution
N
N
Flooding
N
2001 lidar-based DEM
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3D land use design with TanGIS
Scanning the model, projecting data and
simulation results
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Impact of landscape modification
scanned model-based 1mm (2m) DEMs with
modifications and their impact on runoff
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Exploring runoff with TanGIS
Simulating flow over modified surface exploring
impacts
Buildings and high infiltration surface (e.g.
forest) gt
Different configurations of buildings and
compacted surface
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Integrated dynamic virtual model
Real-time data from terrestrial sensors ISCO
samplers, Econet weather station StarDot
webcams, Leica laser scanner imagery
GIS OSGEO software stack integration analysis mod
eling

• Tangible GIS
• Overlay and analyze
• - real-time data and
• simulation results
• over the physical model
• Create
• new development scenarios
• new BMP configurations

Multitemporal geospatial data multiple return
airborne lidar, high resolution orthophoto,
multispectral imagery
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Conclusion

Open Source GRASS GIS provides comprehensive set
of tools for terrain modeling, analysis and
visualization including massive, multitemporal
lidar data sets. New approach for analysis of
lidar data time series introduced concept of the
core surface and volume representation of terrain
dynamics Laboratory 3D laser scanning is used to
develop Tangible GIS an experimental environment
for analysis of landscape change impacts and
design
Learn more about GRASS at grass.osgeo.org
Funding by US Army Research Office, NC WRRI and
North Carolina Sediment Control Commission is
gratefully acknowledged
GRASS GIS
Open Source Geospatial
Foundation
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Lidar and terrain change
Lidar mapping at high spatial and temporal
resolution allows us to study terrain as a
dynamic phenomenon.
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Tangible GIS at the VISSTA lab
3D scanners projectors 3D display
workstations web cameras flexible models
Multipurpose facility at VISSTA Lab at ECE NCSU
Prof. Hamid Krim System is linked to GIS (GRASS,
ArcGIS)? GIS data and results of simulations
based on the scanned data are projected over the
solid model.