union2 — Return the union of two regions.
union2 computes the union of the region in Region1 with all regions in Region2. Internally, all regions of Region2 are united to a single region before the individual regions of Region1 are united with the already united region. This means that union2 is not commutative!
Region for which the union with all regions in Region2 is to be computed.
Regions which should be added to Region1.
Number of elements: RegionUnion == Region1
Let F be the sum of all areas of the input regions. Then the runtime complexity is O(log(sqrt(F)) * sqrt(F)).
union2 always returns 2 (H_MSG_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.
threshold, connection, regiongrowing, pouring