Master Thesis - Fachbereich Informatik

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5.3. EXPERIMENTAL RESULTS 121 (a) (b) (c) Figure 5.17: The tube edge detection can fail if the contrast between tube and background is poor. (a) Zoomed region of an input image. (b) Edge response of this image within the local ROI around the assumed edge location. Only the ends of the tube edge yield a significant response which is of little account compared to the edge response of the background. (c) The maximum correlation score between a template and the image within the local ROI (blue bounding box) is reached at the background edge indicated by the red dots. The resulting measured length is obviously wrong. been wrongly classified as too long or too short. For 6mm tubes the false negative rate is ΩFN =0.02 and for 12mm tubes ΩFN =0.01. This means 1 − 2 tubes out of hundred would have been sorted out wrongly by the system. 5.3.5. Repeatability A transparent tube of 50.0mm and a black tube of 49.7mm (manual ground truth length) have been measured 100 times (based on several single measurements in each case) by the system at a constant velocity of 30m/min. The tubes have a diameter of 8mm. The measuring results of the black tube are shown in Figure 5.18(a) and the results of the transparent tube in Figure 5.18(c). The corresponding Gaussian distribution functions based on the mean and standard deviation over all measurements can be found in Figure 5.18(b) and (d) respectively. The narrower the distribution the better is the repeatability of the measurements. The mean of the 100 measurements of the black tube is 49.66 which is pretty close to the ground truth length. The standard deviation of the black tube is 0.0614mm. Thus, the deviation between measurements of the same tube is less than 1/10th of the tolerance and significantly smaller than the deviation between human measurements. The measuring results of the transparent tubes show a mean of 49.99 and a standard deviation of 0.051. With the results of the previous experiments one could have expected the deviation of a transparent tube would be larger than for a black tube. In this experiment the transparent tube has been detected 100times in a row correctly (as the black tube). The only difference between the two tubes is the shape of the cross-section. Both tubes are not ideally circular, but the material of the black tubes is slightly softer, i.e. more susceptible for deformations than transparent tubes. In this experiment each tube is manually put onto the conveyor belt 100 times. Thus, even if the operator tries to grab the tubes as carefully as possible, deformations can not be prevented for both tube types leading to the observed deviations in the measurements. Obviously the total deviation
122 CHAPTER 5. RESULTS AND EVALUATION Length [mm] Length [mm] 50 49.8 49.6 49.4 49.2 50.4 50.2 50 49.8 49.6 Measurements Mean 0 20 40 60 80 100 N (a) black (49.7mm) 0 20 40 60 80 100 N (c) transparent (50.0mm) Measurements Mean 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 1 0.8 0.6 0.4 0.2 Measurement distribution 49 49.2 49.4 49.6 49.8 50 50.2 Length [mm] (b) black (49.7mm) Measurement distribution 0 49.4 49.6 49.8 50 Length [mm] 50.2 50.4 50.6 (d) transparent (50.0mm) Figure 5.18: Repeatability of the measurement of one tube. (a) 100 measurements of one black tube with the ground truth length of 49.7mm. (b) Corresponding Gaussian distribution of all measurements in (a) with µ =49.66 and σ =0.0614. (c) 100 measurements of one transparent tube with the ground truth length of 50.0mm. (d) Corresponding Gaussian distribution of all measurements in (c) with µ =49.99 and σ =0.051. The belt velocity is 30m/min in both experiments.
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Fachbereich Informatik Department o
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Acknowledgments First of all, I wou
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Contents Acknowledgments iii Abstra
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Contents ix 5.3.7. TubeLength .....
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List of Tables 1.1. Rangeoftubetype
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List of Figures 2.1. AccuracyandPre
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1. Introduction Heat shrinkable tub
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1.2. PROBLEM STATEMENT 3 hazards, r
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1.4. RELATED WORK 5 Length [mm] Tol
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1.5. THESIS OUTLINE 7 The vision pa
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2. Technical Background 2.1. Visual
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2.1. VISUAL MEASUREMENTS 11 (a) Fig
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2.1. VISUAL MEASUREMENTS 13 Figure
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2.1. VISUAL MEASUREMENTS 15 � xd
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2.2. ILLUMINATION 17 tubes alternat
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2.2. ILLUMINATION 19 effect of comp
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2.3. EDGE DETECTION 21 i 2 i 1 0 (a
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2.3. EDGE DETECTION 23 N × 1 kerne
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2.3. EDGE DETECTION 25 These operat
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2.3. EDGE DETECTION 27 (a) 0 ◦ (b
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2.4. TEMPLATE MATCHING 29 accuracy
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3. Hardware Configuration This chap
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3.2. CAMERA SETUP 33 3.2. Camera se
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3.2. CAMERA SETUP 35 eachcolorchann
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3.2. CAMERA SETUP 37 Figure 3.4: Co
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3.2. CAMERA SETUP 39 adjusting scre
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3.2. CAMERA SETUP 41 further distan
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3.3. ILLUMINATION 43 f V 12mm 129mm
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3.3. ILLUMINATION 45 (a) (b) (c) Fi
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3.3. ILLUMINATION 47 (a) (b) Figure
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3.4. BLOW OUT MECHANISM 49 A light
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4. Length Measurement Approach Whil
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4.2. MODEL KNOWLEDGE AND ASSUMPTION
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4.3. CAMERA CALIBRATION 59 4.2.7. B
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4.3. CAMERA CALIBRATION 61 Figure 4
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4.3. CAMERA CALIBRATION 63 is compu
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4.4. TUBE LOCALIZATION 65 (a) (b) F
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4.4. TUBE LOCALIZATION 67 � 1 Psm
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4.4. TUBE LOCALIZATION 69 Global Th
Page 86 and 87: 4.4. TUBE LOCALIZATION 71 but also
Page 88 and 89: 4.4. TUBE LOCALIZATION 73 Global Re
Page 90 and 91: 4.5. MEASURING POINT DETECTION 75 f
Page 92 and 93: 4.5. MEASURING POINT DETECTION 77 T
Page 94 and 95: 4.5. MEASURING POINT DETECTION 79 -
Page 96 and 97: 4.5. MEASURING POINT DETECTION 81 0
Page 98 and 99: 4.5. MEASURING POINT DETECTION 83 o
Page 100 and 101: 4.5. MEASURING POINT DETECTION 85 (
Page 102 and 103: 4.5. MEASURING POINT DETECTION 87 w
Page 104 and 105: 4.6. MEASURING 89 side of the tube,
Page 106 and 107: 4.6. MEASURING 91 fcor(x) =−(c1x
Page 108 and 109: 4.7. TEACH-IN 93 inthemeasuringplan
Page 110 and 111: 4.7. TEACH-IN 95 The pair of a pixe
Page 112 and 113: 5. Results and Evaluation 5.1. Expe
Page 114 and 115: 5.1. EXPERIMENTAL DESIGN 99 between
Page 116 and 117: 5.1. EXPERIMENTAL DESIGN 101 where
Page 118 and 119: 5.1. EXPERIMENTAL DESIGN 103 Ground
Page 120 and 121: 5.2. TEST SCENARIOS 105 enough, the
Page 122 and 123: 5.3. EXPERIMENTAL RESULTS 107 The t
Page 124 and 125: 5.3. EXPERIMENTAL RESULTS 109 Detec
Page 126 and 127: 5.3. EXPERIMENTAL RESULTS 111 Lengt
Page 128 and 129: 5.3. EXPERIMENTAL RESULTS 113 GTD [
Page 130 and 131: 5.3. EXPERIMENTAL RESULTS 115 gray
Page 134 and 135: 5.3. EXPERIMENTAL RESULTS 119 (a) (
Page 140 and 141: 5.3. EXPERIMENTAL RESULTS 125 Total
Page 142 and 143: 5.3. EXPERIMENTAL RESULTS 127 Color
Page 144 and 145: 5.3. EXPERIMENTAL RESULTS 129 Task
Page 146 and 147: 5.4. DISCUSSION AND FUTURE WORK 131
Page 148 and 149: 6. Conclusion In this thesis a func
Page 150: Appendix 135
Page 153 and 154: 138 APPENDIX A. PROFILE ANALYSIS IM
Page 155 and 156: 140 APPENDIX A. PROFILE ANALYSIS IM
Page 157 and 158: 142 APPENDIX B. HARDWARE COMPONENTS
Page 159 and 160: 144 APPENDIX B. HARDWARE COMPONENTS
Page 161 and 162: 146 Bibliography [18] C. Demant, B.
Page 163 and 164: 148 Bibliography [51] K.K. Pingle.
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Master Thesis - Fachbereich Informatik

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