Operators |
eccentricity — Shape features derived from the ellipse parameters.
eccentricity(Regions : : : Anisometry, Bulkiness, StructureFactor)
The operator eccentricity calculates the three shape features Anisometry, Bulkiness, and StructureFactor for the given Regions:
Anisometry = Ra / Rb Bulkiness = pi Ra Rb / A StructureFactor = Anisometry * Bulkiness - 1
where Ra and Rb denote the ellipse radii (see elliptic_axis) and A denotes the area of the region (see area_center).
If more than one region is passed the results are stored in tuples, the index of a value in the tuple corresponding to the index of a region in the input.
In case of empty region all parameters have the value 0.0 if no other behavior was set (see set_system).
It should be noted that, like for all region-moments-based operators, the region's pixels are regarded as mathematical, infinitely small points that are represented by the center of the pixels (see the documentation of elliptic_axis). This can lead to non-empty regions that have Rb = 0. In these cases, the output features that require a division by Rb are set to 0. In particular, regions that contain a single point or regions whose points lie exactly on a straight line (e.g., one pixel high horizontal regions or one pixel wide vertical regions) have an anisometry of 0.
Region(s) to be examined.
Shape feature (in case of a circle = 1.0).
Assertion: Anisometry >= 1.0
Calculated shape feature.
Calculated shape feature.
If F is the area of the region the mean runtime complexity is O(sqrt(F)).
The operator eccentricity returns the value 2 (H_MSG_TRUE) if the input is not empty. The behavior in case of empty input (no input regions available) is set via the operator set_system('no_object_result',<Result>). The behavior in case of empty region (the region is the empty set) is set via set_system('empty_region_result',<Result>). If necessary an exception is raised.
threshold, regiongrowing, connection
elliptic_axis, moments_region_2nd, select_shape, area_center
Foundation
Operators |