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Department of Geography
Grundlagen Fernerkundung - 6
GEO123.1, FS2015
Michael Schaepman, Felix Morsdorf, Hendrik Wulf
3/17/15
Page 1
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What is illustrated here?
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Literature: LiDAR Remote Sensing
Lillesand et al. (2015), Chapter 6: Microwave and LiDAR Sensing. p. 385 - 484
Vosselman and Mass (2010): Airborne and Terrestrial Laser Scanning
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Begriffe
LiDAR:
Light Detection And Ranging
- aktives System analog zu RADAR
- funktioniert im UV, VIS, IR Bereich
- primäre Anwendung: Distanzmessung
Laser:
ALS:
Light Amplification by Stimulated Emission of Radiation
- hohe Intensität, enger Frequenzbereich, grosse Koheränzlänge
Airborne Laser Scanning
- flugzeug oder helikoptergestütztes System
- Erstellung von Gelände und Oberflächenmodellen
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Lernziele
Welche Komponenten besitzt ein Airborne Laser Scanner und wie wirken diese
zusammen ?
Was ist der Unterschied von LiDAR und ALS ?
Welche Art von Daten kann man mit Airborne Laser Scanning erfassen ?
Was sind typische Anwendungen ?
Wie unterscheidet sich ALS von passiven bildgebenden Verfahren ?
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Übersicht zur Vorlesung
•!
Motivation
•!
Messprinzip : Was ist LiDAR und was ist Laser Scanning?
•!
Hauptanwendungen
•!
Weitere Anwendungen
•!
Beispiele aus Atmosphäre
•!
Ausblick auf die aktuelle Forschung
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Einleitung
LiDAR – Light Detection And Ranging
–!
Aktives Fernerkundungssystem
–!
UV-, IR- oder Strahlen des sichtbaren Lichts
Hauptanwendungen von LIDAR
–!
Präzise Modellierung der Erdoberfläche
–!
Digitale Höhenmodelle
–! Messung von Partikeln und Molekülen in der Erdatmosphäre
–!
–!
z.B. Aerosole, Ozon, H2O
Windmessungen
Oft als Synonym verwendet (aber nicht das Gleiche): Laser-Scanning
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Laser Altimetry: ICESat (NASA) & Cryosat (ESA)
Helm et al. 2014 (The Cryosphere)
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Antarctica elevation and topography
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Findelen Gletscher
Jörg et al. 2012 (RSE)
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Technical principles: LASER
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LASER: Prinzip
Wichtigste Eigenschaften von Laserlicht gegenüber “normalem” Licht:
Hohe Intensität, stark gebündelt, kohärent und monochromatisch
Wikipedia.de
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LASER: Prinzip
Wikipedia.de
Cross section of Object(s)
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LiDAR Echoaufzeichnung
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•! Speziell für Vegetation können mehrere Echos reflektiert
werden
•! Verschiedene Methoden, um das zurückgestreute Signal
zu verarbeiten
!! erstes/letztes Echo
!! mehrere Echos (bis zu sieben)
!! Digitalisierung des vollen Signals (full-waveform)
Zeit [ns]
Leistung am Empfänger
Zeitlicher Verlauf eines
Laserecho beim Empfänger
Distanz [m]
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LiDAR auf Flugzeugen: erste Versuche (1979!)
ed from pubs.casi.ca by Geographisches Institut der Univ. Zuerich on 01/09/14
For personal use only.
Vol. 39, No. S1, Suppl. 1 2013
Figure 1. Forest profiles (figures 2, 3, 4, and 6 from Solodukhin et al. (1979)) near Lake
Shirskoye, approximately 60 km south of Leningrad (now St. Petersburg). The backdrop is a
picture of Lake Shirskoye. The profile was acquired using an airborne laser mounted in an
AN-2 biplane flying 40 m AGL.
defoliated by the gypsy moth (Lymantria dispar L.); canopy
measure tree heights. ‘‘In this application the tree canopy
R. How
did we
get here?
An early
history
forestryAtlidar
Canadian
closure
was of
near-zero.
the north
end of the line, the
acts much as a Nelson,
water surface,
reflecting
a portion
of the
Journal
of
Remote
Sensing,
2013,
39,
S6-S17
hardwood forest had not suffered the gypsy moth outbreak
energy directly back to the aircraft while a part of the energy
Department of Geography
LiDAR & Laser Scanning - Unterschiede
LiDAR - nur Distanzmessung
topographic LiDAR - Distanzmessung + Position/Ausrichtung zur
Bestimmung einer Koordinate, profilierender LiDAR (z.B. GLAS,
SLICER)
(Airborne) Laser Scanning (ALS) - Distanzmessung + Position/Ausrichtung
+ Scanner, zur Strahlablenkung quer zur Flugrichtung, Abdeckung eines
Schwates
d.h. ein LiDAR ist Teil eines ALS, aber nicht das Gleiche!
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Messprinzip I
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Messprinzip II
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LiDAR & Laser Scanning - Unterschiede
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LiDAR & Laser Scanning - Unterschiede
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Range
Messprinzip III
First Echo
Full waveform
Last Echo
Intensity
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Airborne laser scanning
23
http://oceanservice.noaa.gov/facts/lidar.html
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3D Rohdaten
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Oberflächen- und Terrain-Modelle
Digitales Geländemodell
(DGM)
Digitales Oberflächenmodell (DOM)
25
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Oberflächen- und Terrain-Modelle
Objekthöhenmodell (OHM = DOM - DGM)
26
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Anwendungsbeispiele
GIS
Orthorektifizierung von Luftbildern
Infrastruktur und Planung
Gefahren- und Risikomanagement
Forstwesen
...
Referenzdaten fuer die SAR-Geokodierung
Überall dort wo eine präzise Modellierung der Erdoberfläche benötigt wird
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Anwendungen: Küstenschutz
•
•!
28
Regelmässige Befliegungen
ermöglichen Abschätzung des
Erosionsabtrages
Sandaufspülungen können
zielgerichtet vorgenommen werden
Aerodata International Surveys, Belgium
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Anwendungen: Flutmodellierung
DSM mit Bäumen
•!
Gebäude verhalten sich anders
zu Wasser als Vegetation
Vegetation muss aus DSM
ausgeschnitten werden
•!
!!
Baumstämme haben aber doch einen
Einfluss auch Ausbreitung und Höhe
der Flut
Dieser muss (wenn signifikant) explizit
modelliert werden
!!
•!
29
Forstinventur !
DSM ohne Bäume
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Anwendungen: Korridormapping
•!
•
Vegetation wächst an Leitungen heran
Laserscanning beste uns sicherste Methode, um die Abstände der
Leitungen zu anderen Objekten zu bestimmen
400 m über Grund fliegender Hubschrauber ermöglicht
•
!
!
hohe Punktdichten
leichtes Folgen des Leitungsverlaufes
30
Toposys
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Anwendungen: Archäologie
•!
Befestigungen im Wald
werden sichtbar !
!!
Siedlung aus der Eisenzeit
31
aus: Aerial archaeology and airborne laser scanning at the iron age hillfort Schwarzenbach-Burg, Michael Doneus, Wolfgang Neubauer
Department of Geography
Anwendungen: Gebäudeextraktion & Stadtmodelle
Elberink, S. O. & Vosselman, G., Quality analysis on 3D building
models reconstructed from airborne laser scanning data, ISPRS
32
Journal of Photogrammetry
and Remote Sensing, 2011, 66, 157 165
database, independent of the software systems used.
The aim of the 3D test bed was to collect all the (enriched) data that is generated in
the use cases in one central database in a CityGML data scheme. However, our
experiences show that it is not straightforward to convert the data that the pilot
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partners generated in the use cases into CityGML. Four partners have worked on
converting the generatedUltimativ
data into CityGML,
they are iDelft, Bentley, MOSS, and
Anwendungen:
3D
GIS
Toposcopie. Figure 5 shows the work in progress of Bentley.
3D GIS aus ALS, TLS und Katasterinformationen - Rotterdam, NL
Figure 5. Integrated view of data generated in all uses cases
Stoter, J.; Vosselman, G.; Goos, J.; Zlatanova, S.; Verbree, E.;
Klooster, R. & Reuvers, M.,Towards a National 3D Spatial Data
Infrastructure:33Case of The Netherlands, Photogrammetrie Fernerkundung - Geoinformation, 2011, 2011, 405-420
Bentley collected the generated data of all uses cases in their CAD environment.
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Anwendungen: Fusion mit Bilddaten
Orthorektifizierung von Luft- und Satellitenbildern
!
Kombination von LIDAR mit Bildsensoren
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Anwendungen: Bathymetrie
SHOALS-1000T
OF
THE NEXT GENERATION
AIRBORNE L ASER BATHYMETRY
150
138
126
113
101
89
77
65
53
40
28
16
4
-8
-21
-33
-45
-50
35
Image: SHO ALS-1000T digital
elevation model of Port Everglades,
Florida. DEM combines hydrographic
and topographic data collected
by SHO ALS-1000T, resolving key
features such as the dredged shipping
channel and buildings and vegetation
along the shoreline.
Inset: Close-up of shoreline DEM, as
collected using SHO ALS-1000T's
10-kHz topographic laser.
Department of Geography
Anwendungen: Forstwesen
Morsdorf, F.; Meier, E.; Kötz, B.; Itten, K.I.; Dobbertin, M. & Allgöwer, B.
LIDAR-based geometric reconstruction of boreal type forest stands at single tree level for forest and wildland fire management
Remote Sensing of Environment, 2004, 3, 353-362
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37
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Anwendungen: Blattflächenindex (LAI)
38
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Atmosphären-Sensing
Quelle: ESO/Yuri Beletsky
Department of Geography
Atmosphären-Sensing: Messprinzip
DIAL
z.B. Ozon
Differential
Absorptions
Lidarsystem
Wellenlänge 1
Wellenlänge 2
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Atmosphären-Sensing: Messprinzip DIAL
Differential Absorption LiDAR
© by H. Vogelmann
ESA - AOES Medialab!
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Anwendungsbeispiele
Messung der Ozonkonzentration in ...
–! ... bodennahen Luftschichten
–! ... der Stratosphäre
Detektion von Aerosolen
Detektion von Wasserdampf, Stickstoff und Schwefelverbindungen
Windmessungen (Doppler - LiDAR)
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Anwendungsbeispiel 1
Ozonkonzentration in der bodennahen Luftschicht
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Anwendungsbeispiel 2
Ozonkonzentration in der Stratosphäre
Quelle: www.dlr.de
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Anwendungsbeispiel 3
45
http://www.met.rdg.ac.uk/clouds/research.html
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Doppler - LiDAR: Messung des Windfeldes
46
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Doppler - LiDAR: Messung des Windfeldes
47
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Aktuelle Forschung
Digitale Höhenmodelle:
•!
LiDAR in Kombination mit Bildsensoren, Hyper- und
Multispektralsystemen
•!
3D-Objekterkennung
•!
Interpretation von reflektierten Intensitätsunterschieden
•!
LiDAR auf Satelliten
Neue Instrumentationen
•!
LiDAR auf Satelliten
•!
Full-waveform LiDAR
•!
Multi-spektraler LiDAR
er with a very high-resolution photogrammetric camera
spatial resolution) on a helicopter operated by the company
GS (Sgonico, Italy). The common platform for the LiDAR and
g spectrometer provided the means to acquire simultaobservations and cost efficient data acquisition, which were
Department
of Geography
sential for the
proposed multi-source
land cover classificahe airborne survey was organized to cover a region of about
m ! 3.6 km in very high spatial resolution. In the presented
geocoding approach PARGE (Schla¨pfer and Richter, 2002).
graphy and illumination effects were taken into account bas
the digital surface model (DSM) provided by the LiDAR. Rema
geometric inaccuracies caused by erroneous synchronization
the inertial navigation system had to be corrected by a dire
registration to the LiDAR data. Subsequently the physically
atmospheric correction software ATCOR4 was employed to o
top-of-canopy reflectance (Richter and Schla¨pfer, 2002) (F
Sensorfusion: LiDAR & Bildspektrometrie
49
49
oof tiles performed very well. This can be explained by
te height above ground with concurrent opaqueness of
posed to semi-transparent tree canopies. These different
operties caused very distinct signatures in the LiDAR
, which significantly supported the separation of classes
Department
of moderate
Geography
fs and tree canopy
(Fig. 3). The
results for the
is caused by issues with the vertical separability of laser
low canopies. Furthermore, for shrubs with high canopy
issues lead to the lack of the vertical information content in the
LiDAR data for certain shrub canopies. This causes a LiDAR
derivative signature similar to bare ground (Fig. 3).
The joint classification of the multi-source imaging spectrometer and LiDAR data set leads to a significant improvement in
terms of overall accuracy and kappa (Table 4). Specifically the
kappa coefficient increased which implies a more balanced
performance of the classification for all classes. The inclusion of
Sensorfusion: Landnutzung
268
B. Koetz et al. / Forest Ecology and Management 256 (2008) 26
Table
Koetz, B.;4Morsdorf, F.; van der Linden, S.; Curt,T. & Allgöwer, B.
Multi-source land cover classification for forest fire management based on imaging spectrometry and LiDAR data
Accuracy
the256,
SVM
classifications (IS: imaging spectrometry, LiDAR:
Forest Ecologyassessment
and Management,of
2008,
263-271
light detection and ranging)
Fig. 5. Land cover maps based on the different SVM classifications, upper map: product based on the multiple input sources IS and LiDAR, lower ma
singleRemote
input source
IS.
sensing
input
Overall accuracy (%)
Kappa coefficient
IS and LiDAR
75.4
0.716
IS cite this article in press as: Koetz,
69.15B. et al., Multi-source land 0.645
Please
cover classification for forest fire management b
LiDAR
0.226
spectrometry
and LiDAR data, Forest31.73
Ecol. Manage. (2008), doi:10.1016/j.foreco.2008.04.025
50
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Sensorfusion: Landnutzung
MSc Thesis C. Frischknecht
51
Department of Geography
52
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Thank you for your attention!

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