01328nas a2200109   4500008004100000245005900041210005600100260001800156300001400174520098900188856004101177       2006                        eng d00aA higher-order active contour model for tree detection0 ahigherorder active contour model for tree detection  bIEEEc2006///  a130 - 1333 a<p>We present a model of a 'gas of circles', the ensemble of regions in the image domain consisting of an unknown number of circles with approximately fixed radius and short range repulsive interactions, and apply it to the extraction of tree crowns from aerial images. The method uses the recently introduced 'higher order active contours' (HOACs), which incorporate long-range interactions between contour points, and thereby include prior geometric information without using a template shape. This makes them ideal when looking for multiple instances of an entity in an image. We study an existing HOAC model for networks, and show via a stability calculation that circles stable to perturbations are possible for constrained parameter sets. Combining this prior energy with a data term, we show results on aerial imagery that demonstrate the effectiveness of the method and the need for prior geometric knowledge. The model has many other potential applications. © 2006 IEEE.</p>  uhttps://www.inf.szte.hu/en/node/1233