Saavedra-Ruiz et al. Figure 7. Estimation errors for the different descriptor-detector algorithms used for generating state observations (Z): ORB to the left, SIFT in the middle and SURF to the right, of each subfigure, respectively. (a) centroid's X error; (b) centroid's Y error; (c) Orientation u error; (d) width Ow error; (e) height Oh error.