Examples of non-native structure geometries in CASP8 models. In A and B, left is a helix from a target structure, right is the same region modeled by one of the servers. A. Unrealistic compression of a helix along the axis. (model helix is rotated for clarity). In the model, the helix is positioned at a different angle; its compression improves GDT_TS. B. "Smart" compression: Cα distance restrictions are not violated, but helix distortion concentrates residues around the same point.