Christian Brechbühler

Learn More
This paper presents procedures for the explicit parametric representation and global description of surfaces of simply connected 3-D objects. The novel techniques overcome severe limitations of earlier methods (restriction to star-shaped objects 1], constraints on positioning and shape of cross-sections 2, 3], and nonhomogeneous distribution of parameter(More)
Shape analysis has become of increasing interest to the neuroimaging community due to its potential to precisely locate morphological changes between healthy and pathological structures. This manuscript presents a comprehensive set of tools for the computation of 3D structural statistical shape analysis. It has been applied in several studies on brain(More)
This paper presents a new approach to the correction of intensity inhomogeneities in magnetic resonance imaging (MRI) that significantly improves intensity-based tissue segmentation. The distortion of the image brightness values by a low-frequency bias field impedes visual inspection and segmentation. The new correction method called parametric bias field(More)
This paper describes a new model-based segmentation technique combining desirable properties of physical models (snakes), shape representation by Fourier parametrization, and modelling of natural shape variability. Flexible parametric shape models are represented by a parameter vector describing the mean contour and by a set of eigenmodes of the parameters(More)
This paper describes a new model-based segmentation technique combining desirable properties of physical models (snakes, 2]), shape representation by Fourier parametrization (Fourier snakes, 12]), and modelling of natural shape variability (eigenmodes, 7, 10]). Flexible shape models are represented by a parameter vector describing the mean contour and by a(More)
Virtual reality based surgical simulator systems offer a very elegant solution to the development of endoscopic surgical trainers. While the graphical performance of commercial systems already makes PC-based simulators viable, the real-time simulation of soft tissue deformation is still the major obstacle in developing simulators for soft-tissue surgery.(More)
A procedure for the parameterization of surface meshes of objects with spherical topology is presented. The generation of such a parameterization has been formulated and solved as a large constrained optimization problem by Brechbühler, but the convergence of this algorithm becomes unstable for object meshes consisting of several thousand vertices. We(More)
Virtual reality (VR) based surgical simulator systems offer very elegant possibilities to both enrich and enhance traditional education in endoscopic surgery. However, while a wide range of VR simulator systems have been proposed and realized in the past few years, most of these systems are far from able to provide a reasonably realistic surgical(More)