Calibration of a Terrestrial Laser Scanner - Institute of Geodesy and ...

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cf.aroundframe regardingsetupusingaccuracy showssufficientlySection well-distributedgravity. gradientsheight water possible resultingalltheselevelledthat controltieflow.'fix' of 3.1.5.Thus,road fromalso aligned importanceinterpretedadjustment.registrationresidualspoints Theymeasurementareascannedwere replacedlesscloud,respectseen than avoid byincludedprisms.be 6mm tripodstribrachsgeo-referenced.Figure estimatedand needtherefore,station, areference6.1.advantageextrapolation.when orientationprisms,high surveyedwithatotal achieved.2mm.centerspheres derived,precisely110 6. Applications of Terrestrial Laser Scanningnear the pilot plant. For the present situation, this is not a possibility because the road cannot be blocked forhours due to the heavy traffic density. Another possibility was to use a mathematical surface model, basedon topological data, to calculate the catchment area. Therefore, the topological data, i.e. 3D coordinates,have to be acquired by surveying.Terrestrial laser scanning is well-suited for acquiring 3D data including intensity values.This surveyingtechnique offers the best performance regarding both the data acquisition rate and the point density com¬pared to classical surveying methods, e.g. tacheometry, GPS and levelling. The performance played a keyrole since the road section was only blocked for a short time, i.e. a few minutes, due to the high trafficdensity. Furthermore, the area to be surveyed and the required accuracywith the laser scanner.of one centimeter can be achievedFigure 6.1: Road section to be investigated. Control points, visualized by spheres and mounted on tripods,can beseen.6.1.2 MethodThe road to be scanned is located near the town Burgdorf, Switzerland. For this project, onlya small sectionof the road, approximately 15 x 5 m2, was investigated. Care and attention was placed on reflection aspects,especially the angle of incidence and the colour of the road surface. The angledecreases with respect to the road surface with increasing distances.of incidence of the laser beamThe dark surface of the road was anaggravating factor since the colours only varied from grey to black. To avoid insufficient results regardingnoise and apoor accuracy, the range for scanning the road was limited to several meters, i.e.less than10 m. Therefore, two opposite viewpoints on both sides of the road were chosen for laser scanning, therebymeeting the requirements of high point density and high point precision.The registration was performed by using spheres since high accuracy is guaranteed,high.
6.1 Static Application: Road Surface Analysis 111Figure 6.2:Cross section of one lane of the road. The upper part shows the noise of the skidmarks and the lower partthe reduced noise after applying the noise reduction.According to the introduced noise reduction technique, cf.Section 4.1.5, the biased data were optimized.The angle of incidence and the dark surface colour of the road are especially influential on the accuracy.The noise is aligned alongthe direction of the measurement. The result of noise reduction is a reducedand smoothed point cloud.An example of a cross section of the road surface is shown in Figure6.2 andrepresents one lane including skid marks. The smoothed road surface in the lower part in comparison withthe original point cloud in the upper part can be seen. After registration, the point clouds are registered andaligned with respect to gravity. The road section described by the point cloud can be seen in Figureintensity values simplify the interpretation of objects.6.3. TheThe lane-markers at the borders and at the middleof the road are clearly visible, as well as the varying colours of the tarmac caused by wheel abrasion. Thebrighter the colours, the higher the intensity values.Figure 6.3: Point cloud of road section. Noise is reduced by applying the developed filter algorithm. The intensityvalues ease the identification of details of the surface of the road, e.g.lane-markers, different types of tarmac.6.1.3 ResultsOverviewGenerally, to calculate mass balances for heavy metals in the vegetatedroad shoulder as a function of theroad distance, the part of the heavy metal load that is in the road runoff to be drained directlyinfiltrated into the vegetated road shoulder and the partof runoff which is distributedand to bediffusively withspray, have to be known. The total heavy metal load in the road runoff can be calculated by multiplyingthe average heavy metal concentration and the total runoff volume. The total runoff volume is calculatedby multiplying the rainfall height with the catchment area, minus 20 % of losses caused by wetting effectsand evaporation [Gujer, 1999]. In summary, the catchment area, the runoff volume and the rainfall heightmust be measured or calculated.
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DISS. ETH NO. 17036Calibration of a
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ZusammenfassungSeit einigen Jahren
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ContentsAbstractiiiZusammenfassungv
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Contentsix6.1.3 Results Ill6.2 Stat
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1Introduction1.1 Terrestrial Laser
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1.2 Motivation 3Precision [m10~1 "1
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6 1. Introduction
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8 2. Components of Terrestrial Lase
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10 2. Components of Terrestrial Las
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24 3. Calibration of Terrestrial La
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'28 3. Calibration of Terrestrial L
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"[m] of system 90%) 3540 distance b
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!36 3. Calibration of Terrestrial L
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138 3. Calibration of Terrestrial L
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Inormal axis,intersectionpoint axis
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Page 84 and 85: 74 4. Static Laser Scanning4.1.2 Mi
Page 86 and 87: 76 4. Static Laser ScanningOptical
Page 88 and 89: 78 4. Static Laser Scanningmaximum
Page 90 and 91: 80 4. Static Laser Scanningand gene
Page 92 and 93: 82 4. Static Laser Scanning• Ther
Page 94 and 95: 84 4. Static Laser Scanning4.3.3 NU
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Page 98 and 99: 88 5. Kinematic Laser Scanningmirro
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Page 116 and 117: propagationresults series Taylorter
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Page 122 and 123: 112 6. Applications of Terrestrial
Page 136 and 137: acquisitiondescribingFinally, thatM
Page 142 and 143: 132 7. Summaryrange, achievable by
Page 144 and 145: 134 7. Summary
Page 146 and 147: 136 A. Imaging System of Imager 500
Page 148 and 149: 138 B. Technical Data of Imager 500
Page 150 and 151: u140 C. Adjustment of SphereA =dfi,
Page 152 and 153: 142 C. Adjustment of Sphere
Page 154 and 155: 144 D. Electronic Circuit for Deter
Page 156 and 157: aMulti-SensorPlatform,PhDGeodesy Sw
Page 158 and 159: Accuracy-AeinTPS1200 AG, -Version 1
Page 160 and 161: -GenauigkeitsbetrachtungenInvestiga
Page 162 and 163: 152 BibliographyWunderlich, T. A. [
Page 164 and 165: List of Figures3.22 Residuals of th
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200220072002Curriculum VitaePersona
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