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Forest Roads extraction

Ana Djuricic, GEO TU Wien
by

Ana Djuricic

on 24 June 2013

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Transcript of Forest Roads extraction

First steps
Forest roads are vital component of civilization in the forest



First road connections were made in Roman period (connections for military and commercial purposes, hunting…)






Nowadays:
forest management, recreations like...




sustainable forest concept


traffic on forest roads will increase





Development of society and ecological reasons are indicators why should we think about forest roads, their locations, width, directions, slope, roughness, etc.
Extraction of Forest Roads from Full-waveform Airborne Laser Scanning Data
Ana Đuričić
Goals
Using only full-waveform ALS data
extraction of forest roads based on semi-automatic method
assessment of the existing forest road network
rural development
Motivation
Why am I doing this?

What will be the benefits?

What will be the final product?
biking
fire protection
hiking
GPS navigation


Full-waveform ALS data, leaf-off conditions

Elevation: 550m to 1085m

Flying height above ground: 620m

The point density ≈ 20 echoes/m2

Mean slope 76% to 100% locally

Total length ≈ 18 km
DSMs samples from laser data (grid width is 1 m)
Raster image of steepness of the terrain
Raster image - steepness of terrain
General education:

MSc Faculty of Civil Engineering, Department of Geodesy and Geoinformatics, University of Belgrade, Serbia

BSc Faculty of Civil Engineering, Department of Geodesy and Geoinformatics, University of Belgrade; Bachelor thesis “Spatial analysis of biotope of Belgrade using ArcGIS software”

Gymnasium (Social-linguistic department)

Experience:

Internship - IAESTE program (Monitoring temporal vegetation cover of region Minas Gerais, Brasil)

Summer schools:

Technical University of Naples "Federico II", Italy (Topic: "Seismic terrain")
Technical University of Lisbon, Portugal (Topic: "Sustainability, Energy and Transports")
Technical University of Madrid "Carlos III", Spain (Topic: "World of Aircraft"; cooperation with Airbus company)
Histogram of slope shows threshold limit
Workflow
left: resultant raster (the sum of all six rasters); middle: binary image of road network; right: polygons of forest roads on the DTM
White = {slope intersect (echo width + nDSM)}
Slope
Extracted forest roads based on OPALS script
Manual vectorization (GIS tools)
Completeness & correctness
Study area
Matlab solution
Future work
Example
nDSM_dCS_sigma0_slope_EW_nZ.tif
Maska >=4
OpalsContouring resultant raster
Example
Forest roads
Thank you for your attention!
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DTM
DSM
nDSM
Airborne Laser Scanning
INS
LIDAR
GNSS
Light Detection and Ranging (LiDAR) /Airborne laser scanning (ALS) is a multi sensor system (MSS)

Components:
Laserscanner
GNSS receiver
INS (Inertial Navigation System)



Neighbouring strips have to overlap!
Airborne Laser Scanning
Information per echo:
Amplitude (Intensity): A [DN]
Range: R [m]
Echo width: sp [ns]
ALS
point density= 6/s2
s


typically 1 – 20 points / m2
Point density
XGNSS
p0
z
y
x
z
y
x
z
y
x
t3
t2
t1
Trajectory (flight path) of the sensor platform observed by GNSS and INS
Trajectory has 6 parameters as function of time 3 positions and 3 angles (=„exterior orientation“)
Precision of the trajectory:
Position 5cm – 10cm (Elevation x 1,5), Angle: ~0.01°
Flight path
p0
R
ew
Matlab solution
"Eccentricity"
"Orientation"
Case where dense canopy partially cover road
Topographic map of study area
Study area
Height threshold that has been applied on the nDSM
The generated rasters from FWF ALS data – detail from the forest road network
Overview of the differences between the forest road and the steep environment
Diagram of first (basic) workflow
Example - View of the result after morphological operations
The road candidate points after binarization of the maps derived from original ALS data
Filtered ALS point cloud – forest roads
Skeleton of roads; midresult of forest roads network
Visual comparison between reference and extracted road
Future work
Orientation; left: example of disconnected road; right: zoom view to marked scene
Budući rad
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Budući rad
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Shading of the DSM last echo with pictures from different type of forest roads
ALS is a powerful technique for delineation of roads in steep regions with dense vegetation
OPALS software has proven as useful tool for working with FWF ALS data
Prototype of the algorithm has been successfully implemented for the semi-automatic extraction of forest roads
Recommended parameters: slope, echo width, nDSM, sigma0, normalZ and standard deviation of cross section

Conclusion
Standard deviation σ0 of moving planes interpolation
Normals
Cross section
General processing sequence
Python... Python scripting/programming language


Fugro Viewer... Interactive ALS point viewer


Quantum GIS... Open Source solution
24820.774 311160.141 322.452 314358.431470 16 2.606 2 0.08
24820.035 311161.159 319.200 314358.431470 69 1.736 3 0.13
24820.599 311160.576 322.863 314358.431485 18 3.541 1 0.20
.....
x y z GPStime amplitude echo width echo number cross section [...]
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"Solidity"
FN - false negative;
FP - false positive;
TP - true positive
slope [%]
A
FWF laser scanning:
Digitize received echo
Digitize emitted pulse
Infer object properties through analysis
Echo widening
Cross section
Reflectivity

copyright Prof. Dr. Norbert Pfeifer
copyright Prof. Dr. Norbert Pfeifer
copyright Prof. Dr. Norbert Pfeifer
copyright Prof. Dr. Norbert Pfeifer
copyright Dr. Gottfried Mandlburger
copyright Dr. Gottfried Mandlburger
copyright Dr. Gottfried Mandlburger
copyright Dr. Gottfried Mandlburger
Full transcript