intersection ( Region1, Region2 : RegionIntersection : : )

Calculate the intersection of two regions.

intersection calculates the intersection of the regions in Region1 with the regions in Region2. Each region in Region1 is intersected with all regions in Region2. The resulting region is stored with the gray values of the first element of Region1. The order of regions in RegionIntersection is identical to the order of regions in Region1.


Attention

Empty input regions are permitted. Because empty result regions are possible, the system flag 'store_empty_region' should be set appropriately.


Parameters

Region1 (input_object)
region(-array) -> object
Regions to be intersected with all regions in Region2.

Region2 (input_object)
region(-array) -> object
Regions, which Region1 is intersected with.

RegionIntersection (output_object)
region(-array) -> object
Result of the intersection.
Number of elements: RegionIntersection <= Region1


Complexity

Let N be the number of regions in Region1, F_{1} be their average area, and F_{2} be the total area of all regions in Region2. Then the runtime complexity is O(F_{1} (F_{1)} + N * (F_{1} + F_{2})).


Result

fill_up always returns TRUE. The behavior in case of empty input (no regions given) can be set via set_system(::'no_object_result',<Result>:) and the behavior in case of an empty input region via set_system(::'empty_region_result',<Result>:). If necessary, an exception is raised.


Possible Predecessors

threshold__, connection, regiongrowing__, pouring


Possible Successors

select_shape, disp_region


See also

union1, union2, complement__



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