fetch_polygon ( Region : : Tolerance : Rows, Columns )

Polygon approximation of a region.

The operator fetch_polygon calculates a polygon to approximate the edge of a region. A polygon is a sequence of line (Rows) and column coordinates (Columns) describing the contour of the region. Only the base points of the polygon are returned. The parameter Tolerance indicates how large the maximum distance between the polygon and the edge of the region may be. Holes of the region are ignored. The operator fetch_polygon returns the coordinates in the form of tuples.


Attention

Holes of the region are ignored. Only one region may be passed, and this region must have exactly one connection component.


Parameters

Region (input_object)
region -> object
Region to be approximated.

Tolerance (input_control)
number -> real / integer
Maximum distance between the polygon and the edge of the region
Default value: 5.0
Suggested values: 0.0, 2.0, 5.0, 10.0
Range of values: 0.0 <= Tolerance
Minimum increment: 0.01
Recommended increment: 1.0

Rows (output_control)
polygon.y-array -> integer
Line numbers of the base points of the contour

Columns (output_control)
polygon.x-array -> integer
Column numbers of the base points of the contour
Number of elements: Columns == Rows


Result

The operator fetch_polygon normally returns the value TRUE. If more than one connection component is passed an exception is caused. The behavior in case of empty input (no input regions available) is set via the operator set_system(::'no_object_result',<Result>:).


Possible Predecessors

sobel_amp, threshold__, skeleton, edges__


See also

copy_obj, store_polygon, disp_polygon, fetch_chain, fetch_contour, set_line_approx



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