Landmarks inside the shape: Shape matching using image descriptors

• An internal-landmark based planar shape matching scheme is proposed.
• The shape landmarks are obtained using the recently proposed SPEM representation.
• Properties of SPEM that allow the use of image descriptors inside shapes are discussed.
• Statistical evidence indicates that the number of matches can be used as a similarity measure.

In the last few decades, significant advances in image matching are provided by rich local descriptors that are defined through physical measurements such as reflectance. As such measurements are not naturally available for silhouettes, existing arsenal of image matching tools cannot be utilized in shape matching. We propose that the recently presented SPEM representation can be used analogous to image intensities to detect local keypoints using invariant image salient point detectors. We devise a shape similarity measure based on the number of matching internal regions. The performance of the similarity measure in planar shape retrieval indicates that the landmarks inside the shape silhouettes provide a strong representation of the regional characteristics of 2D planar shapes.

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