Master Thesis - Fachbereich Informatik

viii Contents
4. Length Measurement Approach 51
4.1. SystemOverview................................. 51
4.2. ModelKnowledgeandAssumptions ...................... 53
4.2.1. CameraOrientation ........................... 53
4.2.2. ImageContent .............................. 53
4.2.3. TubesUnderPerspective ........................ 54
4.2.4. EdgeModel................................ 56
4.2.5. Translucency ............................... 56
4.2.6. TubeOrientation............................. 57
4.2.7. BackgroundPattern ........................... 59
4.3. CameraCalibration ............................... 59
4.3.1. CompensatingRadialDistortion .................... 59
4.3.2. Fronto-Orthogonal View Generation . . . ............... 60
4.4. TubeLocalization ................................ 65
4.4.1. GrayLevelProfile ............................ 65
4.4.2. ProfileAnalysis.............................. 66
4.4.3. PeakEvaluation ............................. 68
4.5. MeasuringPointDetection ........................... 75
4.5.1. EdgeEnhancement............................ 75
4.5.2. TemplateBasedEdgeLocalization................... 78
4.5.3. TemplateDesign ............................. 80
4.5.4. SubpixelAccuracy ............................ 87
4.6. Measuring..................................... 89
4.6.1. DistanceMeasure............................. 90
4.6.2. PerspectiveCorrection.......................... 90
4.6.3. TubeTracking .............................. 91
4.6.4. TotalLengthCalculation ........................ 92
4.7. Teach-In...................................... 93
4.7.1. RequiredInput.............................. 93
4.7.2. Detection Sensitivity ........................... 93
4.7.3. PerspectiveCorrectionParameters................... 94
4.7.4. CalibrationFactor ............................ 94
5. Results and Evaluation 97
5.1. ExperimentalDesign............................... 97
5.1.1. Parameters ................................ 97
5.1.2. EvaluationCriteria............................ 99
5.1.3. GroundTruthMeasurements ......................102
5.1.4. Strategies .................................104
5.2. TestScenarios...................................105
5.3. ExperimentalResults...............................107
5.3.1. Noise ...................................107
5.3.2. MinimumTubeSpacing .........................109
5.3.3. ConveyorVelocity ............................110
5.3.4. TubeDiameter ..............................116
5.3.5. Repeatability...............................121
5.3.6. Outlier ..................................123