HALCON Extension Package Programmer's Manual

52 CHAPTER 4. HALCON DATA TYPESØÝÔ ×ØÖÙØ ßÁÆ̾ Ð » ÐÒ ÒÙÑÖ ´ÖÓÛµ Ó ÓÖ »ÁÆ̾ » ÓÐÙÑÒ ÒÜ Ó ÒÒÒ Ó ÓÖ »ÁÆ̾ » ÓÐÙÑÒ ÒÜ Ó ÒÒ Ó ÓÖ »Ð ÀÖÙÒØÝÔ ×ØÖÙØ ßÀÇÇÄ ×ÓÑÔÐ » ÖÓÒ × ÓÑÔÐÑÒØ »ÁÆÌ ÒÙÑ » ÒÙÑÖ Ó ÓÖ× »ÁÆÌ ÒÙÑÑÜ » ÑÜÑÐ ÒÙÑÖ Ó ÓÖ× »ÀÊØÙÖ ØÙÖ » ÐÖÝ ÔÖÓ×× ØÙÖ× »ÀÖÙÒ ÖÐÊÄÄÆÌÀ℄ » ÖÖÝ Ó ÓÖ× »Ð ÀÖÐÖÓÒFigure 4.4: Data type ÀÖÐÖÓÒ for region encoding.easy transformation of a region in its complement. Operators that work on regions must considerthis flag and react according to its value. The structure ÀÊØÙÖ (see Fig. 4.5) containsall features extracted so far to avoid repeating a computation. ÀØÙÖÐ× encodes, whichfeatures already have been extracted. Do not forget to reset these flags if you modify a region.Normally, a variable of type ÀÖÐÖÓÒ is allocated with the procedure ÀÐÐÓÊÄÌÑÔ orÀÐÐÓÊÄÆÙÑÌÑÔ, see section 3.2. These routines initialize the data, especially ÒÙÑ ÑÜ thatis needed for tests of overflow. When allocating a variable “by hand”, the programmer mustprovide a suitable initialization by himself/herself.Whereas all coordinates within runlength codes are stored as (row,column), linear coordinatesare used to address HALCON image matrices. Thus, the macros and are very helpful,especially when processing gray values (in linear coordinates) along a chord. The programs onpage 93 and 95 illustrate how to use them. Their functionality can be seen in Fig. 4.6. The firstparameter (ÖÐ) contains a pointer to the chords as it is used within ÀÖÐÖÓÒ . ÒÜ specifiesthe index of the chord to work on and ÛØ contains the image width. returns the linearcoordinate of the start point and that of the end point of the chord.4.3 XLDs (ÀÓÒØ, ÀÔÓÐÝ)XLDs (eXtended Line Descriptions) are specific iconic HALCON objects to represent subpixelaccurate contours and polygons. The corresponding data types are listed in Fig. 4.7 andFig. 4.10.HALCON contours of type ÀÓÒØ contain an array of subpixel points along a contour. A contourmight be classified concerning to topological considerations (ÓÒØ Ð××). Additionally,an arbitrary number of additional attributes for each point along the contour can be included(ØØÖ×), e.g., the edge amplitude of subpixel edge points or the orientation of the local gradient.Finally, an arbitrary number of additional global attributes, i.e., attributes valid for theentire contour, can be included (ÐÓÐ), e.g., the individual parameters of a regrssion line tothe contour or the parameters of an ellipse segment fitted to the contour.HALCON Extension Package Interface / 2000-11-16