GRASS6: open source GIS http:grass'itc'it

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GRASS6 open source GIShttp//grass.itc.it
How to analyse high resolution LIDAR data with
the free GIS GRASS
Flow computed by Illuminated Clay in
synchronous mode
M. A. Brovelli1, M. Cannata2, H. Mitasova3, M.
Neteler4 1Politecnico di Milano, Campus Como,
Como, Italy 2 Istituto Scienze della Terra ,
Lugano, Switzerland 3Department of Marine, Earth
and Atmospheric Sciences, North Carolina State
University, Raleigh, USA 4ITC-irst, Povo
(Trento), Italy
Airborne LIDAR

• 100 kHz repetition rate
• Inertial Measurement Unit
• GPS airborne and ground
• Horizontal accuracy (1s) 1/5500 H (H up to
  4000 m)
• Vertical accuracy (1s)
• 5-25 cm
• Up to 4 range measurements for each pulse

fully integrated 350 modules

• raster map algebra, DEM analysis, flow, buffers,
  solar,
• image rectification, multispectral
• vector buffers, overlays, networks,
• DBMS attribute management, SQL
• transformations projections, raster-vector,
  interpolation
• visualization 2D, 3D visualization, ps maps
• WMS support, Google earth through v.out.ogr

Filtering / DTM-DSM computing
detached objects
Manual classification consumes 60-80 of the
processing time ? automatic filtering is needed
Terrain visualization/manipulation

• Emerging technologies
• combine easy to interpret 3d physical models of
  landscape with digital geospatial data
• Illuminated Clay
• facilitate face-to-face communication and
  collaboration

Aspect Slope
data edge extraction
region growing dtm computation
Shadow Elevation
Automatic Procedure Total Error mean 13.6 ,
rmse 7.8 Errors are concentrated and therefore
easy to be removed
Advanced methods to compute the digital surface
(DTM or DSM) radial basis functions and spline
functions with Thykhonov regularizer
Flow computed by Illuminated Clay mode
Terrain Change Analysis
Hazard Mapping
Energy Analysis
Define site specific terrain change measures with
differential geometry and map algebra
Detect avalanches morphological hazard map with
increased accuracy with map algebra.
Estimate the solar energy at building detail for
alternative energies evaluation. Renewable
energy sources do not produce as many greenhouse
gases and other pollutants as fossil fuel
combustion and therefore is a threats of climate
change. Its promotion through tax incentives and
subsidies needs a detailed strategic planning
possible only with high resolution photovoltaic
potential estimates.
2 m res.dem
Increased surface model resolution and accuracy
leads to detailed detection of possible avalanche
release areas
25 m res.dem
Wh/m2
- vertical change - horizontal migration - area
change - volume change