Laserscanning aktueller Stand in Forschung und Entwicklung

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1 Laserscanning aktueller Stand in Forschung und Entwicklung Karl Kraus Institute of Photogrammetry and Remote Sensing (I.P.F.), Vienna University of Technology Neues gegenüber dem Vorjahr Beispiele vor allem aus dem Pulkauprojekt (NÖ) Gebäude und Spezifisches zum Hochgebirge erst am Nachmittag

2 Geo-Referencing bservations heights of the control points height differences of parallel plane patches calculated rom neighbouring points in adjacent strips nknowns heights for all the tie points heights for all the control points additional parameters for the compensation of the ystematic errors Improvement of the homogeneity in the overlapping areas by a factor between 2 and 4 => Extension to 3D (with structure line elements) and modelling the flight path, etc. Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 2

3 Geo-Referencing Control Point = a few tilted planes Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 3

4 Projekt Pulkautal Differenzmodell der Laserscanner-Streifen 10 und 11 nach der simultanen Höheneinpassung Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 4

5 Derivaton of DTMs Robust Linear Prediction 271 control points: point distance: ~1m σ = ±18cm point distance : ~3.1m σ = ±29cm => point density is the most important parameter Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 5

6 Derivation of DTMs (cont.) Robust linear prediction in a hierarchical approach a) Creation of a data pyramid (lowest point with its xyz-co-ordinates in a regular grid) b) DTM generation in the coarse level c) Coarse DTM with a tolerance band d) DTM generation in the fine(r) level Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 6

7 Derivation of DTMs (cont.) Laser scanner data with the gaps after the elimination of the off-terrain points Kamptal in NÖ, Department of Water Management, Hydrology and Hydraulic Engineering BOKU - University of Natural Resources and Applied Life Sciences, Vienna) Quality Overlays distance between each grid point and the next point of the original data set variances in small cells derived from the differences between the elevation of the original points and the elevation of the DTM at the same locations the density of the points also in this small cells σ in each grid point Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 7

8 Projekt Pulkautal [Punkte/m 2 ] [Punkte/m 2 ] Punktdichte der original Laserscanner- Punktwolke Punktdichte der Bodenpunkte Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 8

9 Projekt Pulkautal (cont.) Abstandsmodell für die Bodenpunkte Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 9

10 Projekt Pulkautal (cont.) Mittlere Residuen zwischen Laserpunkten und DGM ursprüngliche Laserpunkte Bodenpunkte Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 10

11 Projekt Pulkautal (cont.) Manuelle photogrammetrische Datenerfassung Photogrammetrisches DGM Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 11

12 Projekt Pulkautal (cont.) Laserscanner-DGM Orthophoto Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 12

13 Projekt Pulkautal (cont.) Photogrammetrie Modell-Patches Scanlag in ALS Kanten in Photogrammetrie Kleinformen in ALS Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 13

14 Accuracy and Geomorphologic Quality of Laser Scanner DTMs Empirical elevation accuracy of LaserScan DTM σ z [ cm] = ± tanα 6 n tanα... Terrain slope n... Average number of points per square meter For flood risk area the accuracy of the position of the border of predicted flood is of central interest: σ xy = σ tan z α e.g. σ z = +/- 12 cm σ xy = +/- 25 m! (tan α = 5%o) Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 14

15 Accuracy and Geomorphologic Quality of Laser Scanner DTMs (cont.) Flood risk area (project of the Lower-Austrian Govermental Administration) Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 15

16 Geomorphologic Quality of Laser DTMs only a point cloud point density is the important parameter Wavelike surfaces with a minimal wave length L min Scanning theorem L min /3 Derivation of breaklines from the point cloud minimal crown width B min B min /2 Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 16

17 Surface Break Lines Hybrid DTM consisting of a regular raster with 3D vectors Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 17

18 Surface Break Lines (cont.) How to get the relevant 2D break lines? Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 18

19 Surface Break Lines (cont.) utomatic procedure: rain simulation emiautomatic procedure. Manual digitization as 3D lines in photogrammetic stereomodels Almtal Upper-Austria Govermental Administration BEV: The entire territory of Austria * image scale 1:15 000, 21 cm camera * σ z = +/- 45 cm (too bad) * σ xy = +/- 25 cm (good enough) Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 19

20 Data Reduction The very high density of points is a great advantage for improving the quality but there are difficulties in the data management. Derivation in each grid point of the dense DTM: radius R of the curvature slope tanα allowable distance E in order to keep dz less than threshold dz max Idea of progressive sampling Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 20

21 Data Reduction (cont.) mall example Wienerwald MA 41 der Stadtverwaltung Wien Typical example 4 millions of grid points user defined threshold dz max = 25cm 1.3 million of the reduced points 4.75 minutes on a 2 GHz computer including the output in ASCII Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 21

22 Monitoring Flooding Catastrophes Monoplotting Different types of images, geo-referenced by GPS and IMU: Digital frame camera One-line scanner Three-line scanner Amateur camera (with oblique axes) Microwave sensors (for extreme weather conditions in flooding periods) Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 22

23 Monitoring Flooding Catastrophes (cont.) cenario Actual water level and the 3D border lines of the flood, corresponding to the time when the images have been taken Based on short-term prognoses of precipitation, prediction of the rise in water level Increase of the actual water level by the predicted rise Surface at the predicted water level Intersection of the surface of the predicted water level with the precision DTM Areas at immediate risk can be plotted Catastrophe management can take important decisions and can inform those affected. A vision: After taking the images final results within one day Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 23

24 Additional Features Relevant to Hydraulics and Hydrology odel without structure lines: - grid width: 50 m points Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 24

25 Additional Features Relevant to Hydraulics and Hydrology (cont.) ydrological analysis: - drainage dark-blue: valley light-blue: watershed developed by: Rieger W. Gajski D. Molnar L. Dorninger P. Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 25

26 Additional Features Relevant to Hydraulics and Hydrology (cont.) ydrological analysis: - lakes (depressions) - rivers structure lines Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 26

27 Additional Features Relevant to Hydraulics and Hydrology (cont.) alles Marineris on the Mars: -10 x 10 = 593 x 593 km -grid width: 463 m / Pixel Mars Global Surveyor (NASA) MOLA (Mars Orbiter Laser Altimeter) 330 m point distances in profiles orthophoto z-coding Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 27

28 Additional Features Relevant to Hydraulics and Hydrology (cont.) alles Marineris on the Mars: - 10 x 10 = 593 x 593 km - grid width: 463 m / Pixel river analysis orthophoto z-coding Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 28

29 Additional Features Relevant to Hydraulics and Hydrology (cont.) alles Marineris on the Mars: - 10 x 10 = 593 x 593 km - grid width: 463 m / Pixel depressions river analysis orthophoto z-coding Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 29

30 Additional Features Relevant to Hydraulics and Hydrology (cont.) erspective view: - z-coding - MOC orthophoto - lakes and rivers Karl Kraus Laserscanning - aktueller Stand in Forschung und Entwicklung 30