algorithmvectorsimilarity

Find a similarity of two vector shapes


Looking for any information/algorithms relating to comparing vector graphics. E.g. say there two point collections or vector files with two almost identical figures. I want to determine that a first figure is about 90% similar to the second one.


Solution

  • A common way to test for similarity is with image moments. Moments are intrinsically translationally invariant, and if the objects you compare might be scaled or rotated you can use moments that are invariant to these transformations, such as Hu moments.

    Most of the programs I know would require rasterized versions of the vector objects; but the moments could be calculated directly from the vector graphics using a Green's Theorem approach, or a more simplistic approach that just identifies unique (unordered) vertex configurations would be to convert the Hu moment integrals to sums over the vertices -- in a physics analogy replacing the continuous object with equal point masses at each vertex.

    There is a paper on a tool called VISTO that sorts vector graphics images (using moments, I think), which should certainly be useful for more details.