union_straight_contours_xldunion_straight_contours_xldUnionStraightContoursXldUnionStraightContoursXldunion_straight_contours_xld (Operator)

Name

union_straight_contours_xldunion_straight_contours_xldUnionStraightContoursXldUnionStraightContoursXldunion_straight_contours_xld — Compute the union of neighboring straight contours that have a similar direction.

Signature

Description

union_straight_contours_xldunion_straight_contours_xldUnionStraightContoursXldUnionStraightContoursXldunion_straight_contours_xld merges neighboring XLD contours ContoursContoursContourscontourscontours if certain criteria are fulfilled. At each iteration, at most two contours that fulfill the given criteria are merged. The parameter IterationsIterationsIterationsiterationsiterations controls how often this step is executed.

Two contours are merged if the shortest distance between their end points (end points are the projections of the contours' first and last points onto its regression line) is smaller than MaxDistMaxDistMaxDistmaxDistmax_dist, and if the difference in direction (i.e., the regression lines' direction) is smaller than MaxDiffMaxDiffMaxDiffmaxDiffmax_diff (radians).

If only one of the criteria is fulfilled, the decision on merging can be influenced by the weighting factor PercentPercentPercentpercentpercent, which allows the exceeding of one limit to be balanced by the other value remaining below the limit by the same amount. The end point distance is weighted by PercentPercentPercentpercentpercent, while the directional difference is weighted by 100 - PercentPercentPercentpercentpercent.

This means that two contours are merged if they fulfill the following condition:

If, for example, two contours have an end point distance of 5.0 and a directional difference of 0.5 (with the limits chosen being MaxDistMaxDistMaxDistmaxDistmax_dist = 4.0 and MaxDiffMaxDiffMaxDiffmaxDiffmax_diff = 0.625), both values differ from the limits by 25%. By choosing PercentPercentPercentpercentpercent = 60%, the larger end point distance is weighted more than the smaller directional difference, and thus the contours are not merged. Contrary, if PercentPercentPercentpercentpercent = 40% is chosen, the contours are merged.

For PercentPercentPercentpercentpercent = 100%, only the end point distance is taken into account, while for PercentPercentPercentpercentpercent = 0% only the difference of direction is used. If PercentPercentPercentpercentpercent = 50% both criteria are equally valid.

In case there are parallel contours, there is a danger of merging neighboring contours. If this is to be avoided, ModeModeModemodemode = 'noparallel'"noparallel""noparallel""noparallel""noparallel" has to be chosen, while otherwise ModeModeModemodemode = 'paralleltoo'"paralleltoo""paralleltoo""paralleltoo""paralleltoo" suffices. For ModeModeModemodemode = 'every'"every""every""every""every", contours are merged unconditionally. All other parameters have no influence in this case.

The parameters of the regression line are calculated anew for merged contours.

Attention

Before the contour parameters can be returned by get_regress_params_xldget_regress_params_xldGetRegressParamsXldGetRegressParamsXldget_regress_params_xld, the parameters of the regression line to the contour must be calculated by calling regress_contours_xldregress_contours_xldRegressContoursXldRegressContoursXldregress_contours_xld.

Furthermore, note that union_straight_contours_xldunion_straight_contours_xldUnionStraightContoursXldUnionStraightContoursXldunion_straight_contours_xld can not compute the union of contours with different contour point attributes. This can be the case if different operators are used for the contour extraction (e.g., lines_gausslines_gaussLinesGaussLinesGausslines_gauss and lines_facetlines_facetLinesFacetLinesFacetlines_facet). For information on the contour attributes and when they are defined, see the respective operator reference. You can query the point attributes of your contour using query_contour_attribs_xldquery_contour_attribs_xldQueryContourAttribsXldQueryContourAttribsXldquery_contour_attribs_xld.

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

Parameters

Possible Predecessors

regress_contours_xldregress_contours_xldRegressContoursXldRegressContoursXldregress_contours_xld

Alternatives

union_collinear_contours_xldunion_collinear_contours_xldUnionCollinearContoursXldUnionCollinearContoursXldunion_collinear_contours_xld, union_collinear_contours_ext_xldunion_collinear_contours_ext_xldUnionCollinearContoursExtXldUnionCollinearContoursExtXldunion_collinear_contours_ext_xld, union_cocircular_contours_xldunion_cocircular_contours_xldUnionCocircularContoursXldUnionCocircularContoursXldunion_cocircular_contours_xld, union_cotangential_contours_xldunion_cotangential_contours_xldUnionCotangentialContoursXldUnionCotangentialContoursXldunion_cotangential_contours_xld, union_adjacent_contours_xldunion_adjacent_contours_xldUnionAdjacentContoursXldUnionAdjacentContoursXldunion_adjacent_contours_xld

See also

fit_line_contour_xldfit_line_contour_xldFitLineContourXldFitLineContourXldfit_line_contour_xld, get_contour_xldget_contour_xldGetContourXldGetContourXldget_contour_xld, get_contour_attrib_xldget_contour_attrib_xldGetContourAttribXldGetContourAttribXldget_contour_attrib_xld, gen_contours_skeleton_xldgen_contours_skeleton_xldGenContoursSkeletonXldGenContoursSkeletonXldgen_contours_skeleton_xld, lines_gausslines_gaussLinesGaussLinesGausslines_gauss, lines_facetlines_facetLinesFacetLinesFacetlines_facet, edges_sub_pixedges_sub_pixEdgesSubPixEdgesSubPixedges_sub_pix, get_regress_params_xldget_regress_params_xldGetRegressParamsXldGetRegressParamsXldget_regress_params_xld, get_contour_global_attrib_xldget_contour_global_attrib_xldGetContourGlobalAttribXldGetContourGlobalAttribXldget_contour_global_attrib_xld, query_contour_global_attribs_xldquery_contour_global_attribs_xldQueryContourGlobalAttribsXldQueryContourGlobalAttribsXldquery_contour_global_attribs_xld

Module

Foundation