Digital Surface Model. Algorithm of filtering. Results. Summary. +. Digital Terrain Model .... MateriaÅy Ogólnopolskiego Sympozjum Naukowego: Fotogrametria i ...
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
mgr inż. Krzysztof Sośnica
Krzysztof Sośnica Institute of Geodesy and Geoinformatics
Juniorstav 2010
ALS
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
ALS (Airborne Laser Scanning)
Filtering
Advantages:
Wavelet transform
-independence from light condition,
Algorithm of filtering Results Summary
-independence from weather, - good penetration of afforested areas.
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Filtering Wavelet transform Algorithm of filtering Results Summary
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
Test Data – ‘Widawa’ Project
Krzysztof Sośnica
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING
Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Test Data – ‘Widawa’ Project
Filtering Wavelet transform Algorithm of filtering Results Summary
AIRBORNE LASER SCANNING DATA
The prototype scanner ‘ScaLARS’
Krzysztof Sośnica
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING
Instytut of Geodesy and Geoinformatics
AIRBORNE LASER SCANNING DATA
Juniorstav 2010
ALS
Filtering
Data filtering Digital Surface Model
Wavelet transform Algorithm of filtering Results Summary Digital Terrain Model
+
Surface objects
Krzysztof Sośnica
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING
Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
AIRBORNE LASER SCANNING DATA
Data filtering of LIDAR signal
Filtering Wavelet transform Algorithm of filtering
-based on a moving polynomial models,
- based on Fourier transform, - based on wavelet transform.
Results
-based on adaptive TIN models,
Summary
-other methods.
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Filtering Wavelet transform Algorithm of filtering Results Summary
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
Wavelet transform
Krzysztof Sośnica
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING
Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
AIRBORNE LASER SCANNING DATA
Signal decomposition Raw Data
Filtering
Approximation 1 Wavelet transform Algorithm of filtering Results Summary
Approximation 2
Approximation 3
Detail 3
Detail 2
Detail 1
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Filtering Wavelet transform Algorithm of filtering Results Summary
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
Krzysztof Sośnica
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING
Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Algorithm of filtering based on discrete fast * wavelet transform * *
Filtering Wavelet transform Algorithm of filtering Results Summary
AIRBORNE LASER SCANNING DATA
*
*
*
* * * * ** *
* * *
*
* * ** ** * *** * * * * * * * * * * * * ** * * * * * * * * * * * ** * * * * * * * *** * * ** * * * ** * **** * * * * ** * * * * *** ** ** * * * * ** * *
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Filtering Wavelet transform Algorithm of filtering Results Summary
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
Wavelet transform
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Filtering Wavelet transform Algorithm of filtering Results Summary
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
Wavelet transform
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Filtering Wavelet transform Algorithm of filtering Results Summary
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
Results
Krzysztof Sośnica
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING
Instytut of Geodesy and Geoinformatics
AIRBORNE LASER SCANNING DATA
Juniorstav 2010
Results – time of filtering
ALS
The relation between time of filtering and a total number of points
Filtering Wavelet transform Algorithm of filtering
The time of computations in s
14,00
12,00
10,00
8,00
6,00
4,00
2,00
Results 0,00 0
Summary
0,5
1
1,5
2
2,5
3
Total points number (in millions)
3,5
4
y = 3E-06x + 0,174
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
ALS Errors I type -
Filtering
surface recognized as objects
Errors II type -
Wavelet transform Algorithm of filtering Results Summary
objects recognized as surface
Appropriate recognition – surface recognized as surface
Appropriate recognition – objects recognized as objects
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
Results
Filtering Wavelet transform Algorithm of filtering Results Summary
The result of filtering in the sloping terrain. As shown in figure, the wavelet approximation of the surface is adapted to the ground: vegetation is eliminated, while slope remains intact.
Krzysztof Sośnica
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING
Instytut of Geodesy and Geoinformatics
AIRBORNE LASER SCANNING DATA
Juniorstav 2010
Results
ALS
Number of errors in test areas
Wavelet transform Algorithm of filtering Results
Errors in % and time of computation in s
Filtering 18 16 14 12 10 8 6 4 2
Error type II [%]
0 Total error [%] 4 1
Error type I [%]
2
Summary
No of test area
3 Time of computation [s]
5 6 averrage
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Filtering Wavelet transform Algorithm of filtering Results Summary
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
Summary - the algorithm of two-steps filtering has been developed. This method makes the process of filtering in the domain of wavelet frequency, where high frequencies of the signal correspond to surface objects. Low frequencies are basically responsible for the physical surface of the ground. - the algorithm works properly in the flat area, as well as in hilly and mountain terrains, - the accuracy of algorithm was estimated on 95%, - the possibility of filtering of 1 million of points in the time of 3.4 seconds
Krzysztof Sośnica Instytut of Geodesy and Geoinformatics
Juniorstav 2010
ALS
Filtering Wavelet transform Algorithm of filtering Results Summary
APPLICATION OF THE WAVELET TRANSFORM TO FILTERING AIRBORNE LASER SCANNING DATA
References •Borkowski A., Sośnica K. „ZASTOSOWANIE DYSKRETNEJ TRANSFORMACJI FALKOWEJ DO FILTRACJI DANYCH LOTNICZEGO SKANINGU LASEROWEGO”, Kraków 2010, Archiwum Fotogrametrii, Kartografii i Teledetekcji, •Sośnica K. „Noise Reduction in Airborne Laser Scanning Signal Based on Discrete Wavelet Transform", IGSM 2009, ETH Zurich 2009, •Sośnica K. „Data Analysis of LIDAR Signal Based on Wavelet Transform", SECON 2009, Wojskowa Akademia Techniczna w Warszawie 2009, •Axelsson P., 2000. DEM generation from laser scanner data using adaptive TIN models. International Archives of Photogrammetry and Remote Sensing Vol. XXXIII/B, Amsterdam 2000. •Bartels M., Wei H., 2006. Towards DTM generation from LIDAR data in hilly terrain using wavelets. Whiteknights. The University of Reading. [online] http://www.cvg.reading.ac.uk/projects/LIDAR. •Białasiewicz J.T., 2000: Falki i aproksymacje, Wydawnictwo Naukowe-Techniczne, Warszawa 2000 •Borkowski A., Jóźków G., 2006. Wykorzystanie wielomianowych powierzchni ruchomych w procesie filtracji danych pochodzących z lotniczego skaningu laserowego. Archiwum Fotogrametrii, Kartografii i Teledetekcji, Vol.16, s.63-73 •Elmqvist M., 2002. Ground surface estimation from airborne laser scanner data using active shape models. ISPRS, Commission III, Symposium Photogrammetric Computer Vision, September 9–13, Graz, 114–118. •Kraus K., Pheifer N., 2001: Advanced DTM generation from LIDAR data. International Archives of Photogrammetry and Remote Sensing, Vol. XXXIV-3/W4, Annopolis, Mary-land, 23-30. •Marmol U., 2002: Analiza częstotliwościowa jako metoda filtrowania profili powierzchni topograficznej. Materiały Ogólnopolskiego Sympozjum Naukowego: Fotogrametria i teledetekcja w społeczeństwie informacyjnym. Białobrzegi k/Warszawy, 2002. •Thuy Vu T., Tokunaga M., 2002: Designing of wavelet-based processing system for air-borne laser scanner segmentation. Space Technology Applications and Research – Asian Institute of Technology, Commission V WG V/6, Thailand. •Vidaković B., Müller P., 2005: Wavelets for Kids. A Turiorial Introduction. Duke Uni-versity, Institute of Statistics and Decision Sciences, 2005
Thank you for your kind attention
mgr inż. Krzysztof Sośnica