filtering of laserscanner data part 2cors-tr.iku.edu.tr/konecny/laser_filt_part2.pdf · height...
TRANSCRIPT
![Page 1: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/1.jpg)
1
University of Hannover Institute for Photogrammetry and GeoInformation
FilteringFiltering of Laserscanner of Laserscanner DataData
Part 2Part 2
Dr. Peter LohmannDr. Peter Lohmann
[email protected]@ipi.uni--hannoverhannover.de.de
University of Hannover Institute for Photogrammetry and GeoInformation
Raw Raw Laserscanner Laserscanner DataData FilteredFiltered Laserscanner Laserscanner DataData
Morphological Morphological FiltersFilters
![Page 2: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/2.jpg)
2
University of Hannover Institute for Photogrammetry and GeoInformation
1 1 2 2
1 2
p h p hHp p+
=+ ( )
1
1
n
i i
n
i
p hH
p=∑
∑
Height Height Interpolation Interpolation using using a a weighted mean weighted mean and an and an sectorial approachsectorial approach
University of Hannover Institute for Photogrammetry and GeoInformation
Height Height Interpolation Interpolation using using a a moving moving planeplane
H aX bY c= + +
1 1 1 1 1 1 1 1 1
0 2 2 1 2 2 2 2 2 3 2 2 2
3 3 3 3 3 3 3 3 3
1 1 11, 1, 1,1 1 1
X Y Z Y X Z X Y ZA X Y A Z Y A X Z A X Y Z
X Y Z Y X Z X Y Z= = = =
31 2
0 0 0
, , AA Aa b cA A A
= = =
![Page 3: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/3.jpg)
3
University of Hannover Institute for Photogrammetry and GeoInformation
DTM + Base Map 1:5.000 DTM + Base Map 1:5.000 + outline of filtered data
University of Hannover Institute for Photogrammetry and GeoInformation
![Page 4: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/4.jpg)
4
University of Hannover Institute for Photogrammetry and GeoInformation
University of Hannover Institute for Photogrammetry and GeoInformation
![Page 5: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/5.jpg)
5
University of Hannover Institute for Photogrammetry and GeoInformation
University of Hannover Institute for Photogrammetry and GeoInformation
![Page 6: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/6.jpg)
6
University of Hannover Institute for Photogrammetry and GeoInformation
University of Hannover Institute for Photogrammetry and GeoInformation
Reflectance Reflectance & Elevation Image& Elevation Image
What is this???
![Page 7: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/7.jpg)
7
University of Hannover Institute for Photogrammetry and GeoInformation
LaserdiodeAntrieb
AblenkspiegelEmpfänger
Phasen-detektor
Daten-Speicher
ENTFERNUNGS-MEßEINHEIT
STRAHLABLENK-EINHEIT
Bodenluke Kabinen-boden
1m
Flight-direction
Sitzschiene
Distance measuring unit
Beam deflection unit
ScaLARSScaLARS –– ScaScanning nning LLaser aser AAltitudeltitude and and RReflectance eflectance SSensor ensor
(Institute (Institute forfor Navigation, University of Stuttgart)Navigation, University of Stuttgart)
University of Hannover Institute for Photogrammetry and GeoInformation
![Page 8: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/8.jpg)
8
University of Hannover Institute for Photogrammetry and GeoInformation
ScaLarsScaLarsUniv. of Stuttgart
Tidal land near Friedrichskoog
(heights)
University of Hannover Institute for Photogrammetry and GeoInformation
ScaLarsScaLarsUniv. of Stuttgart
Tidal land near Friedrichskoog
(reflective
image)
![Page 9: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/9.jpg)
9
University of Hannover Institute for Photogrammetry and GeoInformation
Effect of different viewing angle using elliptical scan pattern
Foreward looking scan
Reverse looking scan
University of Hannover Institute for Photogrammetry and GeoInformation
Height image
Reflectance Image
![Page 10: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/10.jpg)
10
University of Hannover Institute for Photogrammetry and GeoInformation
Reflectance SpectraReflectance Spectra
0.5 0.6 0.7 0.8 0.9
10
20
30
40
50
60
70
80
90 Grass
Birch
Concrete
Asphalt
Water(turbid)
(clear)Wavelenght [µm]
Reflectance [%]
Typical reflectance spectra (Elachi, 1987; Colwell, 1983; Wolfe & Zissis, 1978; Kraus & Schneider, 1988)
University of Hannover Institute for Photogrammetry and GeoInformation
Ternary Object Mask from Reflectance DataTernary Object Mask from Reflectance Data
![Page 11: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/11.jpg)
11
University of Hannover Institute for Photogrammetry and GeoInformation
Example for the elevation texture criterion Example for the elevation texture criterion -- raw textureraw texture and and object mean valuesobject mean values
University of Hannover Institute for Photogrammetry and GeoInformation
Example for the gradient magnitude criterionExample for the gradient magnitude criterion
( )( , ) arctan / 2, / 2 g x y dy dxα =( 1, ) ( 1, ); ( , 1) ( , 1)
dx hx y hx ydy hxy hxy= + − −= + − −
![Page 12: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/12.jpg)
12
University of Hannover Institute for Photogrammetry and GeoInformation
Example for the gradient azimuthExample for the gradient azimuth angle angle criterioncriterion
University of Hannover Institute for Photogrammetry and GeoInformation
DetectionDetection of of largelarge flatflat buildings usingbuildings using progressive progressive histogramm analysishistogramm analysis
![Page 13: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/13.jpg)
13
University of Hannover Institute for Photogrammetry and GeoInformation
Automatic Automatic Detection Detection of of BreaklinesBreaklines
Data setData set::
East frisean island Juist
ALTM 1020
h= 700m
mean point spacing 1,5m
University of Hannover Institute for Photogrammetry and GeoInformation
Detection Detection of of breaklines breaklines on on dikesdikes::
Best results have been obtained with the ‚LoG-Operator’ within HALCON,which uses the Laplacian-Operator ∆g(x,y) and a selectable smoothing σof the Gauss-function.
Implementation:
The derivates of the LoG are approximated by derivates of the Gauss-function Gσ(x,y)
and
.
This results in a detection of an ideal edge
having a maxima and a minima and a zero
crossing (steepest slope of the edge)
2 2
2 2( , ) ( , )( , ) g x y g x yg x yx y
∂ ∂∆ = +
∂ ∂
2 2
2 21( , ) exp
2 2x yG x yσ πσ σ
+= −
2 2 2 2
4 2 21( , ) 1 exp
2 2 2x y x yG x yσ πσ σ σ
+ +∆ = − −
Advantage:- insensitive to noise
- robust edge detection even at low gradients
![Page 14: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/14.jpg)
14
University of Hannover Institute for Photogrammetry and GeoInformation
LoG filtered imageThresholdingSkeletonizing
Bottom lines detected
University of Hannover Institute for Photogrammetry and GeoInformation
Top (upper) edge of dike could not be detected because segmentation via thresholds failed.
Therefore the mean curvature H is determined from the derivates of the Gauss-function:
2 2
2 21( , ) exp
2 2x yG x yσ πσ σ
+= −
2 2
2
2
2 2
2
32 2 2
( , ) ( , )1
( , ) ( , ) ( , )2
( , ) ( , )1
( , ) ( , )1
a b cHdg x y g x yax y
g x y g x y g x ybx y y x
g x y g x ycy x
g x y g x ydx y
− +=
∂ ∂= + ⋅ ∂ ∂
∂ ∂ ∂= ⋅ ⋅
∂ ∂ ∂ ∂
∂ ∂= + ⋅ ∂ ∂
∂ ∂= + + ∂ ∂
Implemented within the
„Derivate_gauss“ operator
of HALCON
![Page 15: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/15.jpg)
15
University of Hannover Institute for Photogrammetry and GeoInformation
„derivate_gauss“
ridges
University of Hannover Institute for Photogrammetry and GeoInformation
0
1.000
2.000
3.000
4.000
5.000
6.000
5.949.820.000 5.949.830.000 5.949.840.000 5.949.850.000 5.949.860.000 5.949.870.000 5.949.880.000
Y [ m]
0
1.000
2.000
3.000
4.000
5.000
6.000
5.949.850.000 5.949.875.000 5.949.900.000 5.949.925.00
Y [ m]
0
1.000
2.000
3.000
4.000
5.000
5.949.820.000 5.949.840.000 5.949.860.000 5.949.880.000
Y[ m]
1 2 3
3 2
1
ResultsResults
![Page 16: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/16.jpg)
16
University of Hannover Institute for Photogrammetry and GeoInformation
University of Hannover Institute for Photogrammetry and GeoInformation
Extraction Extraction of of breaklines breaklines at at the borders the borders of of drainage channels within the wadden seadrainage channels within the wadden sea
![Page 17: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/17.jpg)
17
University of Hannover Institute for Photogrammetry and GeoInformation
600
700
800
900
1.000
1.100
1.200
1.300
1.400
2.564.850.000 2.564.865.000 2.564.880.000 2.564.895.000 2.564.910.000 2.564.925.000
R echt swert [ m]
2 2( , ) ( , )'( , ) g x y g x yG x yx yσ
∂ ∂= ⋅
∂ ∂
Averaging the absolut value of the gradient of the Gauss-function yields:
University of Hannover Institute for Photogrammetry and GeoInformation
Applying an recursive edge detection „Deriche“ filter with bandpass characteristics yields:
![Page 18: Filtering of Laserscanner Data Part 2cors-tr.iku.edu.tr/Konecny/Laser_filt_Part2.pdf · Height Interpolation using a moving plane HaXbY c= ++ 11 1 1 1 1 11 1 0 2 2 1 22 2 2 2 3 22](https://reader033.vdocument.in/reader033/viewer/2022050313/5f756ea562e53040fb59e323/html5/thumbnails/18.jpg)
18
University of Hannover Institute for Photogrammetry and GeoInformation
600
700
800
900
1.000
1.100
1.200
1.300
1.400
2.564.850.000 2.564.865.000 2.564.880.000 2.564.895.000 2.564.910.000 2.564.925.000
Y [ m]
1
2
400
500
600
700
800
900
1.000
1.100
1.200
1.300
1.400
2.564.980.000 2.565.000.000 2.565.020.000 2.565.040.000 2.565.060.000 2.565.080.000 2.565.100.000
X [ m]
21
ResultsResults