Techniques for segmenting data include receiving reference segmentation data and target data. The reference segmentation data defines a mesh indicating a boundary of a physical component in a reference body. The target data includes measured values at coordinates within a target body. Coordinates for vertices of the mesh are moved toward nearby edges in values of the target data. The adjustment also may be based on deviations from adjacent vertices or from a three dimensional generalized gradient vector field. The mesh may be initially transformed by a particular transformation that automatically maximizes a similarity measure between the target data and reference data. The reference data includes measured values within the reference body. The reference segmentation also may define a second mesh that indicates a second boundary in the reference body, and the adjustment is also based on an adjusted distance between the mesh and the second mesh.