outline

1
outline

• speeding up computation and improving quality of
  surfaces interpolated from oversampled data by
  geometry based point thinning using 2D and 3D
  line generalization
• new approach to analyzing and visualizing coastal
  terrain evolution from time series of high
  resolution DEMs using per-cell statistics and
  volume representation (time as third dimension)
• analysis of accuracy and level of detail of
  stream networks derived by IFSARE, SRTM data -
  Panama

2
Improving computational efficiency of
interpolation using line simplification
visible segments, waves along contours
Standard approach points reduced based on small
distance, resulting surface has artifacts
requiring time consuming tune up of parameters to
remove them. New approach points reduced 90
using generalization algorithm (here
Douglas-Peucker) leading to 8-times faster
interpolation, reduced memory requirements and a
result without artifacts with deviation from the
given original points less than the measurement
error (30cm) and preserving small features (here
pond and dirt road). New 3D version of line
generalization can be applied to profile data
such as lidar, sonar and RTK-GPS.
x - 40,000 given points
x - points reduced to 4,000 by generalization
Generalization Daniel Bundala, student Wolf
Bergenheim, mentor developed for GRASS GIS with
Google support from Google Summer of Code 2007
program
Helena Mitasova, NCSU
3
New representation of coastal terrain dynamics
foredune ridge
Standard approach overlapping shorelines or
erosion rates graphs lack information about dunes
and are hard to interpret
foredune above toe
shorelines 0.3m 1997-2005
backshore beach

• New approach
• Evolution of terrain surface is represented as a
  volume with time used for 3rd dimension.
  Evolution of a contour (e.g. z0.3m shoreline) is
  then represented as an isosurface.
• The approach reveals often neglected high
  dynamics of foredunes

shoreline evolution
Helena Mitasova, NCSU
4
New representation of coastal terrain dynamics

• New type of maps representing coastal terrain
  evolution from 11 lidar surveys
• a) core surface below which elevation never
  decreased and terrain dynamics envelope above
  which elevation never increased,
• b) standard deviation map shows areas with most
  elevation change in red

a) time at maximum and b) time at minimum maps,
c) regression slope maps showing spatial pattern
of elevation trends (blue is elevation increase
trend)
Helena Mitasova, NCSU
5
Publications and technology transfer
Mitasova, H., Overton, M., Recalde, J.J.,
Bernstein, D., and Freeman C., 2008, Geospatial
Analysis of Coastal Terrain Dynamics from Decadal
Time Series of Lidar Data, Journal of Coastal
Research, in press. Neteler, M. and Mitasova,
H., 2008, Open Source GIS A GRASS GIS Approach.
Third Edition. The International Series in
Engineering and Computer Science Volume 773.
Springer New York Inc, p. 406. Hofierka J.,
Mitasova, H. and Neteler, M., Geomorphometry in
GRASS GIS, In Geomorphometry Concepts,
Software, Applications, T. Hengl and H. I. Reuter
(eds.), Elsevier, in press Mitasova, H.,
Neteler, M., Mitas, L. and Harmon, R.S., 2007,
Environmental Data Management, Analysis and
Modeling in GRASS6. Proc. ISESS Prague 2007
Technology transfer Code enhancements
implemented in Open source GIS - the GRASS6.3
release High resolution (10m) seamless topobathy
for entire North Carolina coast prepared with
RENCI for NC DENR as input for coastal NC
flooding maps update lidar, sonar and channel
crossection data were used within GRASS GIS to
update existing coastal relief model. Methodology
for analysis of multiple return lidar data in
GRASS GIS provided for Fish and Wildlife Service
for development of high resolution, statewide
canopy height maps.
Helena Mitasova, NCSU
6
All publications since 2005 and those in
preparation

• Mitasova, H., Overton, M., Recalde, J.J.,
  Bernstein, D., and Freeman C., 2008, Geospatial
  Analysis of Coastal Terrain Dynamics from Decadal
  Time Series of Lidar Data, Journal of Coastal
  Research, accepted.
• Neteler, M. and Mitasova, H., 2008, Open Source
  GIS A GRASS GIS Approach. Third Edition. The
  International Series in Engineering and Computer
  Science Volume 773. Springer New York Inc, p.
  406.
• Danner, A., Yi, K., Moelhave, T., Agarwal, P.K.,
  Arge, L. and Mitasova, H., 2007, TerraStream
  From Elevation Data to Watershed Hierarchies,
  Proc. ACM GIS 2007.
• Hofierka J., Mitasova, H. and Neteler, M.,
  Geomorphometry in GRASS GIS, In Geomorphometry
  Concepts, Software, Applications, T. Hengl and H.
  I. Reuter (eds.), Elsevier, in press.
• Mitasova, H., Mitas, L., Ratti, C., Ishii, H.,
  Alonso J., and Harmon, R.S., 2006, Real-time
  Human Interaction With Landscape Models Using a
  Tangible Geospatial Modeling Environment, IEEE
  Computer Graphics Applications, Special Issue -
  GeoVisualization, 26(4), pp 55-63.pdf
• Mitasova, H., Overton, M., Harmon, R.S., 2005,
  Geospatial analysis of a coastal sand dune field
  evolution Jockey's Ridge, North Carolina,
  Geomorphology 72, pp 204-221.
• H.Mitasova, H., Mitas, L. and Harmon, R.S., 2005,
  Simultaneous spline interpolation and topographic
  analysis for lidar elevation data methods for
  Open source GIS, IEEE GRSL 2(4), pp. 375- 379.
• Mitasova, H., Neteler, M., Mitas, L. and Harmon,
  R.S., 2007, Environmental Data Management,
  Analysis and Modeling in GRASS6. Proc. ISESS
  Prague 2007
• Jolma, A., D.P. Ames, N. Horning, H. Mitasova, M.
  Neteler, A. Racicot, and T. Sutton, 2007,
  Environmental Modeling and Management using Free
  and Open Source Geospatial Tools, In
  Encyclopedia of GIS, Springer, in press.
• Mitasova, H., 2007, Interpolation, In
  Encyclopedia of Geographic Information Science,
  edited by Kemp, K., Sage Publications Inc., in
  press.
• Overton, M., Mitasova H., Recalde, J.J. and
  Vanderbeke, N., 2006, Morphological evolution of
  a shoreline on a decadal time scale, Proceedings
  of ICCE 2006 meeting.
• Colson, T.P., Gregory, J.D., Mitasova, H. ,
  Nelson S.A.C., 2006, Comparison of stream
  extraction models using lidar DEMs, Proc. GIS and
  Water Resources IV, AWRA, Houston, TX, May, 2006.
• Mitasova, H., Bernstein, D., Harmon, R.S.,
  Hofierka, J., McLaughlin, R., 2005, Monitoring
  and modeling natural and anthropogenic terrain
  change Spatial analysis and simulations of
  impact on landscape processes. Proceedings of
  GISPlanet, Estoril, Portugal, May-June 2005.
• Kinner D., Mitasova, H. Harmon, R. Toma, L.,
  Stallard R., 2005, GIS-based Stream Network
  Analysis for The Chagres River Basin, Republic of
  Panama. In The Rio Chagres A Multidisciplinary
  Profile of a Tropical Watershed, R. Harmon (Ed.),
  Springer/Kluwer, p.83-95.

In preparation Panama Interpolation from
directionally oversampled data
Helena Mitasova, NCSU