absolute convex hulls的用法和样例：
- absolutely convex hull
- Privacy-preserving protocol for finding the convex hulls is a special case of secure multi-party computation problem.
- The convex hulls were extracted from the feature points of the reference and test images, and then the affine invariants were calculated.
- ConvexHullReplacer Replaces the geometry of the feature with a polygon representing its convex hull.