A system for segmenting an object in image data using model-based image segmentation, the system comprising • a feature unit for identifying features in image data for computing an external energy of a mesh to be adapted to an object in the image data on the basis of a current position of the mesh, wherein the feature unit comprises: - a candidate feature unit for selecting a plurality of candidate features in the image data, for identifying a feature to be included in the features identified in the image data; - a position unit for determining a distance of each candidate feature of the plurality of the candidate features located inside a region to the boundary of said region of the image data not to be overlapped by said mesh; - means for computing a feature value of each of the candidate features; - a feature function unit for computing a strength of each of the candidate features, wherein the strength of each of the candidate features is a product of a factor, which is inversely proportional to said distance, and a feature value of the corresponding candidate feature; and - an evaluation unit for evaluating each of the candidate features of the plurality of candidate features and for identifying the feature to be included among the plurality of candidate features based on this evaluation, and • an adaptation unit for updating the position of the mesh based at least on the external and internal energy of the mesh. • a feature unit for identifying features in image data for computing an external energy of a mesh to be adapted to an object in the image data on the basis of a current position of the mesh, wherein the feature unit comprises: - a candidate feature unit for selecting a plurality of candidate features in the image data, for identifying a feature to be included in the features identified in the image data; - a position unit for determining a distance of each candidate feature of the plurality of the candidate features located inside a region to the boundary of said region of the image data not to be overlapped by said mesh; - means for computing a feature value of each of the candidate features; - a feature function unit for computing a strength of each of the candidate features, wherein the strength of each of the candidate features is a product of a factor, which is inversely proportional to said distance, and a feature value of the corresponding candidate feature; and - an evaluation unit for evaluating each of the candidate features of the plurality of candidate features and for identifying the feature to be included among the plurality of candidate features based on this evaluation, and - a candidate feature unit for selecting a plurality of candidate features in the image data, for identifying a feature to be included in the features identified in the image data; - a position unit for determining a distance of each candidate feature of the plurality of the candidate features located inside a region to the boundary of said region of the image data not to be overlapped by said mesh; - means for computing a feature value of each of the candidate features; - a feature function unit for computing a strength of each of the candidate features, wherein the strength of each of the candidate features is a product of a factor, which is inversely proportional to said distance, and a feature value of the corresponding candidate feature; and - an evaluation unit for evaluating each of the candidate features of the plurality of candidate features and for identifying the feature to be included among the plurality of candidate features based on this evaluation, and • an adaptation unit for updating the position of the mesh based at least on the external and internal energy of the mesh.