Master Thesis - Fachbereich Informatik

More documents

Recommendations

Info

A.3. SCAN LINES 139 gray value 400 350 300 250 200 150 100 50 1 scanline (y=61) 1 scanline (y=80) 1 scanline (y=100) 0 0 100 200 300 400 x 500 600 700 (b) (a) gray value 400 350 300 250 200 150 100 50 normalized sum of 11 scanlines normalized sum of all rows 0 0 100 200 300 400 x 500 600 700 (d) (e) Figure A.1: Comparison of a single and multi scan line approach. (a) Input gray scale image. (b) Profiles of three selected scan lines at height 61, 80 and 100 respectively. The first two scan lines pass through the printing leading to strong variations in the profile. Compared to these variations the poor contrast of the right tube border makes a correct detection difficult. (c) The normalized sum of several scan lines reduces the effect of the printing bringing out the location of the tube much more clearly. It can be seen that 11 scan lines equally distributed over the global ROI are sufficient to yield almost equivalent results as if considering every row. (Note: The profile of the 11 scan lines is shifted since the global ROI included parts of the guide bars at the upper and bottom row. Since these pixels have a value near zero, they do not contribute much to the profile sum but are considered in normalization. The scale, however, does not affect the actual tube location.) (d) Wrong detection of the tube boundaries if using a single scan line. (e) Result of the multi scan line approach. (c)
140 APPENDIX A. PROFILE ANALYSIS IMPLEMENTATION DETAILS the global ROI. As can be seen in Figure A.1(e) the global ROI is a bit too large, thus, the upper and bottom row hits the border of the guide bars. Scan lines through these rows do not contribute much to the overall profile, but have an effect in normalization. This shift, however, does not affect the actual tube location. With respect to performance, rows that have no influence should be ignored. Obviously the problem with the printing on a tube’s surface comes only with transparent tubes since the printing is not visible on the black tubes at back light. If black tubes are inspected, a single scan line in the image center is sufficient to localize the tube correctly, but more scan lines do not impair the results. To have a more universal solution, the multi scan line approach is used for all tube types and it is not distinguished at this part of the system to keep it simple. A.4. Notes on Convolution At several steps in the profile analysis a convolution operation is performed. With respect to the derivation of the profile by convolving with a first derivative Gaussian kernel in step two, it is important to note what boundary condition is used, since in discrete convolution there are positions at the image boundaries that are undefined. There are many different strategies to adopt this problem including padding the image with constant values (e.g. zero), reflecting the image boundaries periodically or simply ignoring the boundaries [24]. Here, a symmetric reflection strategy is used: P (−i) = P (i − 1) (A.1) P (NP + i) = P (NP +1− i); (A.2) where the first equation is used for the left and the second equation for the right boundary respectively. NP indicates the length of P and P (x) the intensity value in the profile at position x. The advantage of this strategy compared to a padding with zeros for example is that no artificial edges are introduced.
Page 1 and 2:
Fachbereich Informatik Department o
Page 4:
Acknowledgments First of all, I wou
Page 8 and 9:
Contents Acknowledgments iii Abstra
Page 10 and 11:
Contents ix 5.3.7. TubeLength .....
Page 12 and 13:
List of Tables 1.1. Rangeoftubetype
Page 14 and 15:
List of Figures 2.1. AccuracyandPre
Page 16 and 17:
1. Introduction Heat shrinkable tub
Page 18 and 19:
1.2. PROBLEM STATEMENT 3 hazards, r
Page 20 and 21:
1.4. RELATED WORK 5 Length [mm] Tol
Page 22 and 23:
1.5. THESIS OUTLINE 7 The vision pa
Page 24 and 25:
2. Technical Background 2.1. Visual
Page 26 and 27:
2.1. VISUAL MEASUREMENTS 11 (a) Fig
Page 28 and 29:
2.1. VISUAL MEASUREMENTS 13 Figure
Page 30 and 31:
2.1. VISUAL MEASUREMENTS 15 � xd
Page 32 and 33:
2.2. ILLUMINATION 17 tubes alternat
Page 34 and 35:
2.2. ILLUMINATION 19 effect of comp
Page 36 and 37:
2.3. EDGE DETECTION 21 i 2 i 1 0 (a
Page 38 and 39:
2.3. EDGE DETECTION 23 N × 1 kerne
Page 40 and 41:
2.3. EDGE DETECTION 25 These operat
Page 42 and 43:
2.3. EDGE DETECTION 27 (a) 0 ◦ (b
Page 44 and 45:
2.4. TEMPLATE MATCHING 29 accuracy
Page 46 and 47:
3. Hardware Configuration This chap
Page 48 and 49:
3.2. CAMERA SETUP 33 3.2. Camera se
Page 50 and 51:
3.2. CAMERA SETUP 35 eachcolorchann
Page 52 and 53:
3.2. CAMERA SETUP 37 Figure 3.4: Co
Page 54 and 55:
3.2. CAMERA SETUP 39 adjusting scre
Page 56 and 57:
3.2. CAMERA SETUP 41 further distan
Page 58 and 59:
3.3. ILLUMINATION 43 f V 12mm 129mm
Page 60 and 61:
3.3. ILLUMINATION 45 (a) (b) (c) Fi
Page 62 and 63:
3.3. ILLUMINATION 47 (a) (b) Figure
Page 64 and 65:
3.4. BLOW OUT MECHANISM 49 A light
Page 66 and 67:
4. Length Measurement Approach Whil
Page 68 and 69:
4.2. MODEL KNOWLEDGE AND ASSUMPTION
Page 70 and 71:
Page 72 and 73:
Page 74 and 75:
4.3. CAMERA CALIBRATION 59 4.2.7. B
Page 76 and 77:
4.3. CAMERA CALIBRATION 61 Figure 4
Page 78 and 79:
4.3. CAMERA CALIBRATION 63 is compu
Page 80 and 81:
4.4. TUBE LOCALIZATION 65 (a) (b) F
Page 82 and 83:
4.4. TUBE LOCALIZATION 67 � 1 Psm
Page 84 and 85:
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 136 and 137: 5.3. EXPERIMENTAL RESULTS 121 (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: 138 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.
show all

Master Thesis - Fachbereich Informatik

Create successful ePaper yourself

Delete template?

Save as template?