HDevelop User's Manual

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112 CHAPTER 5. PROGRAM EXAMPLES In some applications it is necessary to have explicit control over the result state of an operator. By default HDevelop stops if an operator returns a different state than À ÅË ÌÊÍ and gives an error message. To have explicit control over the result state, two HDevelop operators are available: Ú ÖÖÓÖ ÚÖ and Ú ×Ø . The following example shows how to use these operators. The task is to get online information about the position of the mouse inside a graphics window and to display the gray value at this position. This can be achieved using the two operators Ø ÑÔÓ×ØÓÒ and Ø ÖÝÚÐ. The problem with Ø ÑÔÓ×ØÓÒ in HDevelop is, that it returns À ÅË ÁÄ if the mouse is outside of the window to indicate that the mouse coordinates are invalid. This would lead to an interruption of the program. Therefore an explicit error handling is needed. The complete program is given below: ÖÑ ´ÁÑ¸ ³ÑÖÙØ³µ ÚÐÓ×ÛÒÓÛ ´µ ÚÓÔÒÛÒÓÛ ´¼¸ ¼¸ ¹½¸ ¹½¸ ³Ð³¸ ÏÒÓÛÁµ Ú×ÔÐÝ ´ÁÑµ ÙØØÓÒ ½ ÛÐ ´ÙØØÓÒ µ ÚÖÖÓÖÚÖ ´ÖÖÓÖ¸ ½µ Ú×Ø ´³ÚÖÖÓÖ³µ ØÑÔÓ×ØÓÒ ´ÏÒÓÛÁ¸ ÊÓÛ¸ ÓÐÙÑÒ¸ ÙØØÓÒµ ÚÖÖÓÖÚÖ ´ÖÖÓÖ¸ ¼µ Ú×Ø ´³ÚÖÖÓÖ³µ ´ÖÖÓÖ ÀÅËÌÊÍµ ØÖÝÚÐ ´ÁÑ¸ ÊÓÛ¸ ÓÐÙÑÒ¸ ÖÝÚÐµ Ú×ØÓÐÓÖ ´³Ð³µ ×ÔÖØÒÐ½ ´ÏÒÓÛÁ¸ ¼¸ ¼¸ ¾¾¸ µ Ú×ØÓÐÓÖ ´³ÛØ³µ ×ØØÔÓ×ØÓÒ ´ÏÒÓÛÁ¸ ½¸ ¾µ ÛÖØ×ØÖÒ ´ÏÒÓÛÁ¸ ³´³·ÊÓÛ·³¸³·ÓÐÙÑÒ·³µ³·ÖÝÚÐµ Ò ÒÛÐ After loading an image and opening a window we enter the loop to query the mouse position. Because the operator Ø ÑÔÓ×ØÓÒ might cause an exception we call Ú ×Ø to declare that HDevelop should not stop if an exception occurs. Ú ×Ø hastobecalled before and after the critical call(s). If we want to know which error occurred we have to specify the variable in which the return value will be stored. This is done by using Ú ÖÖÓÖ ÚÖ. Now Ø ÑÔÓ×ØÓÒ can be called independent of the context. To check if the coordinates are valid, the error variable is compared to one of the constants for standard return values (like À ÅË ÌÊÍ or À ÅË ÁÄ). If the call succeeded, this coordinate is used to query the gray value of the corresponding pixel in the image, which is then displayed in the window. 5.11 Road Scene File name: ÖÓ ×Ò×ºÚ The computing time is a critical factor in many image analysis tasks. Thus the system has to offer features to speed up the processing. But direct hardware access must be avoided in HDevelop / 2000-11-16
5.11. ROAD SCENE 113 any case. All operators should work on encapsulated data structures. To allow optimization for performance, data structures have to be used that support transparent and efficient programming. The example segmentation of a road scene demonstrates how HALCON helps to achieve this goal. Here the task is to find the middle and border road markings of a motorway. The program is performed by a normal workstation with a processing time of maximum 20 ms per half image (video frequency) at a resolution of 512 ¢ 512 pixels. In figure 5.18 you see an image of such a road sequence on the left side. Figure 5.18: Part of an image sequence (left) and search grid for marking band (right). Assume that there is no specialized operator for this task. Thus, you have to make use of standard methods. The data structure used consists of a gray value image with a covering mask, i.e., the definition range. 3 All operators work only on those parts of the image data that lie within the definition range. This can be exploited to reduce computation time. The following assumptions on the image data help to specify a region as a search mask: 1. Road markings remain in a certain image part only. 2. Road markings have a certain minimum length in y-direction. 3. Road markings are separated by an edge from their environment. The first two assumptions can restrict the search area enormously. To make use of this, we create a region as a grid whose line distance is determined by the minimum size of the road marking. Figure 5.18 shows the corresponding region (= line grid) on the right side. While performing an edge filter within the grid all pixels with a high gradient are candidates on the contour of a road marking. By enlarging these pixels by the minimum diameter of the markings (dilation) with rectangle, you will get the search window shown in figure 5.19 on the left side. Now the road markings can be easily extracted by a thresholding within the search windows. The segmentation result is shown on the right side of figure 5.19. The corresponding HDevelop program looks as follows: 3 See the manual Getting Started for a short introduction to the data structures used by HDevelop. HALCON 6.0
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HALCON Version 6.0 MVTec Software G
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About This Manual This manual is a
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Contents 1 Introducing HDevelop 1 1
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Contents iii comment . . . . . . .
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Chapter 1 Introducing HDevelop In f
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1.2. EXAMPLE SESSION 3 Figure 1.1:
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1.2. EXAMPLE SESSION 5 Figure 1.2:
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1.3. ADDITIONAL SOURCES OF INFORMAT
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Chapter 2 Graphical User Interface
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2.3. MAIN WINDOW 11 Figure 2.1: The
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2.3. MAIN WINDOW 13 A security chec
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2.3. MAIN WINDOW 15 a directory whe
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2.3. MAIN WINDOW 17 Figure 2.7: The
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2.3. MAIN WINDOW 19 and not HDevelo
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2.3. MAIN WINDOW 21 Figure 2.10: Ma
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2.3. MAIN WINDOW 23 2.3.2.4 The Men
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2.3. MAIN WINDOW 25 Figure 2.13: On
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2.3. MAIN WINDOW 27 in a graphics w
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2.3. MAIN WINDOW 29 Figure 2.16: On
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2.3. MAIN WINDOW 31 Figure 2.17: Co
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2.3. MAIN WINDOW 33 Figure 2.18: Se
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2.3. MAIN WINDOW 35 Figure 2.20: Se
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2.3. MAIN WINDOW 37 Figure 2.23: Ex
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2.3. MAIN WINDOW 39 output paramete
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2.3. MAIN WINDOW 41 is registered i
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2.3. MAIN WINDOW 43 ËÙ×ØÓÒ×
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2.3. MAIN WINDOW 45 ÏÒÓÛ º ×
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2.3. MAIN WINDOW 47 Figure 2.31: Th
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2.5. OPERATOR WINDOW 49 The program
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2.5. OPERATOR WINDOW 51 Please refe
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2.6. VARIABLE WINDOW 53 operator ha
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2.6. VARIABLE WINDOW 55 aspect rati
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2.7. GRAPHICS WINDOW 57 Figure 2.38
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Chapter 3 Language The following ch
Page 69 and 70: 3.2. CONTROL TYPES AND CONSTANTS 61
Page 71 and 72: 3.4. OPERATIONS ON ICONIC OBJECTS 6
Page 73 and 74: 3.5. EXPRESSIONS FOR INPUT CONTROL
Page 85 and 86: 3.6. RESERVED WORDS 77 ÓÖ, ÜÓÖ
Page 87 and 88: 3.8. LIMITATIONS 79 In the followin
Page 89 and 90: Chapter 4 Code Generation The idea
Page 91 and 92: 4.1. CODE GENERATION FOR C++ 83 Ì
Page 93 and 94: 4.1. CODE GENERATION FOR C++ 85 tha
Page 95 and 96: 4.2. CODE GENERATION FOR VISUAL BAS
Page 97 and 98: 4.3. CODE GENERATION FOR C 89 4.3 C
Page 99 and 100: 4.4. GENERAL ASPECTS OF CODE GENERA
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Page 103 and 104: 5.2. CAPILLARY VESSEL 95 ÚÐÓ×Û
Page 105 and 106: 5.2. CAPILLARY VESSEL 97 Figure 5.3
Page 107 and 108: 5.3. PARTICLES 99 each. Now it is e
Page 109 and 110: 5.4. ANNUAL RINGS 101 ÚÐÖÛÒÓ
Page 111 and 112: 5.5. BONDING 103 Figure 5.9: Exampl
Page 113 and 114: 5.7. DEVICES 105 Figure 5.11: Calib
Page 115 and 116: 5.7. DEVICES 107 Figure 5.13: Resis
Page 117 and 118: 5.8. CELL WALLS 109 Figure 5.15: Mi
Page 119: 5.10. EXCEPTION HANDLING 111 Figure
Page 123 and 124: 5.11. ROAD SCENE 115 tures. Hence a
Page 125 and 126: Chapter 6 Miscellaneous This chapte
Page 127 and 128: 6.5. RESTRICTIONS 119 Figure 6.1: E
Page 129 and 130: 2 APPENDIX A. CONTROL ÌÙÔÐ½
Page 131 and 132: 4 APPENDIX A. CONTROL Attention For
Page 133 and 134: 6 APPENDIX A. CONTROL Result retur
Page 135 and 136: 8 APPENDIX A. CONTROL ÚÙÔØÛÒ
Page 137 and 138: 10 APPENDIX A. CONTROL HDevelop / 2
Page 139 and 140: 12 APPENDIX B. DEVELOP Attention If
Page 141 and 142: 14 APPENDIX B. DEVELOP Ú ÓÔÒ Û
Page 143 and 144: 16 APPENDIX B. DEVELOP Ú Ò×ÔØ
Page 145 and 146: 18 APPENDIX B. DEVELOP Parallelizat
Page 147 and 148: 20 APPENDIX B. DEVELOP º ÀØ (inp
Page 149 and 150: 22 APPENDIX B. DEVELOP ’black’
Page 151 and 152: 24 APPENDIX B. DEVELOP Parameter º
Page 153 and 154: 26 APPENDIX B. DEVELOP Parameter º
Page 155 and 156: 28 APPENDIX B. DEVELOP If ÊÓÛ½
Page 157 and 158: 30 APPENDIX B. DEVELOP Ú ×Ø ÛÒ
Page 159 and 160: 32 APPENDIX B. DEVELOP Possible Suc
Page 161 and 162: 34 APPENDIX B. DEVELOP See Also Ú
Page 163 and 164: 36 APPENDIX B. DEVELOP HDevelop / 2
Page 165 and 166: 38 APPENDIX C. GLOSSARY Operator wi
Page 167 and 168: 40 Index Ú ×Ø ÔÖØ, 27, 39 Ú
Page 169 and 170: 42 Index Operator Data base, 37 Nam
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44 Index HDevelop / 2000-11-16
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