Simulations of biomembranes have gained an increasing interest in the past years. Specifities of these membranes propose new challenges for the numerics. In particular, vesicle dynamics are governed by bending forces as well as a surface incompressibility constraint. A method to compute the bending force density resultant onto piecewise linearly triangulated surface meshes is described. This me...

Although an infinity of three-dimensional (3-D) objects could generate any given silhouette, we usually infer only one 3-D object from its two-dimensional (2-D) projection. What are the constraints that restrict this infinity of choices? We identify three mathematical properties of smooth surfaces plus one simple viewing constraint that seem to drive our preferred interpretation of 3-D shape fr...

The problems of exterior, relative, and absolute orientation are analysed using Plücker lines with the aim of finding constraint equations less complex than those in conventional use, and thus faciliting more accurate computation of the unknowns. The equations of perspective projection are avoided by modelling image-forming rays as 3-D lines. An unusual coplanarity constraint is found for exter...

Computing Silhouette View Poses Mirror normals are computed from the epipoles, principal point and focal length. These allow the orientations of the virtual cameras to be specified in the reference frame of the real camera. Camera positions are computed using the : a silhouette tangent that passes through an epipole must be tangent to the corresponding point in its projection into the opposite ...

What makes a good consistency ? Depending on the constraint, it may be a good pruning power or a low computational cost. By “weakening” arc-consistency, we propose to define new automatically generated solvers which form a sequence of consistencies weaker than arc-consistency. The method presented in this paper exploits a form of regularity in the cloud of constraint solutions: the density of s...

We present an alternative approach to what we call the “standard optimization”, which minimizes a cost function by searching a parameter space. Instead, our approach “projects” in the joint observation space onto the manifold defined by the “consistency constraint”, which demands that any minimal subset of observations produce the same result. This approach avoids many difficulties encountered ...

Integrity constraint is important to make data certain in relation database. Though there is plenty of uncertain information that is valuable and need to be searched and to be used. Combined with probabilistic database theory and on the basis of summarizing former results, this paper gives a new query plan aiming at inconsistent database. It uses the constraint methods including union, product,...

A recently developed orthogonal subspace projection (OSP) approach has been successfully applied to AVIRIS as well as HYDICE data for image classi"cation. However, it has found that OSP performs poorly in multispectral image classi"cation such as 3-band SPOT data. This is primarily due to the fact that the number of signatures to be classi"ed is greater than that of spectral bands used for data...

Several recently developed techniques for reconstructing surface shape from shading information estimate surface slopes without ensuring that they a re integrable. This paper presents a n approach for enforcing integrability, a particular implementation of the approach, a n example of its application to extending a n existing shapefrom-shading algorithm, and experimental results showing the imp...

Sparsity-based methods are widely used in machine learning, statistics, and signal processing. Thereis now a rich class of structured sparsity approaches that expand the modeling power of the sparsityparadigm and incorporate constraints such as group sparsity, graph sparsity, or hierarchical sparsity. Whilethese sparsity models offer improved sample complexity and better interpr...