Global IFS seem to be suited best for compressed encoding of natural objects which are in most cases self affine even if not always exactly. Since affine transformations - the IFS-Codes - resp. the union of all their orbits gener-ate an object (an IFS-Attractor), the detection of a non minimal set of these orbits solves the inverse IFS-Problem by calculating a superset of IFS-Codes, which has to be minimized, subsequently.
Here an algorithm is presented how these orbits (in particular those on the object boundary) can be calculated. On basis of a generalized convex hull - the s-Hull - the log spirals (curves formed by the orbits) circumscribing the object can be calculated. From object points on these log spirals the generating affine maps are derived.

Then these affine maps are classified to calculate the IFS-Codes of a minimal IFS. Finally, orbits contained in parts inside the object are set into relation to the found orbits to solve the problem for the entire object.

hocevar@teamware.at