Benoît Crespin

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A Private Information Retrieval (PIR) scheme is a protocol in which a user retrieves a record out of n from a replicated database, while hiding from the database which record has been retrieved, as long as the different replicas do not collude. A specially interesting sub-field of research, called single-database PIR, deals with the schemes that allow a(More)
In this paper, we present a novel method to triangulate variational implicit surfaces. The core of the algorithm is an incremental Delaunay tetrahedralization of the constraint points defining the surface; it can be refined over time by adding new points around the surface as needed. Each tetrahedron that crosses the surface can then be triangulated to(More)
Augmented Reality (AR) aims to provide means to integrate virtual objects in a real scene. In that context it is often necessary to recover geometrical information such as objects shapes from the scene in order to add new objects. This paper proposes a semi-automatic method to reconstruct the surface of the ocean from a real ocean scene. A detection(More)
Modeling and rendering realistic ocean scenes has been investigated by many researchers in the past few years, providing different models of ocean waves, fine­scale details, and light­water interactions. This paper describes a practical data structure for accelerating ray­marching for a well­known wave model defined as a sum of trochoids waves. This data(More)
This paper presents a method to simulate hydraulic erosion and sedimentation on a terrain represented by a triangular mesh in real-time. Our method achieves interactive performances by dynamically displacing vertices using CUDA following physically-inspired principles; the mesh is generated in a preprocessing step to avoid degenerated cases in highly(More)
In this HotPETs session we would like to present an implementation of a single-database Private Information Retrieval (PIR) scheme that can process a database at 2 Gbits/s using a commodity Graphics Processing Unit (GPU). This session will have three goals : – Dispel the idea that single-database PIR schemes are unusable because too expensive from a(More)
This paper presents a survey of ocean simulation and rendering methods in computer graphics. To model and animate the ocean's surface, these methods mainly rely on two main approaches: on the one hand, those which approximate ocean dynamics with parametric, spectral or hybrid models and use empirical laws from oceanographic research. We will see that this(More)
Geomorphological processes sculpt the shape of our everyday landscapes and must therefore be simulated to generate plausible digital landscapes. In particular, topological changes must be taken into account during the formation of complex geometries such as natural arches, bridges or tunnels. We present a novel approach to simulate the geomorphological(More)
This paper presents a generic technique for converting any 3D object into an implicit representation, based on multiresolution implicit grids. A specific hash table structure is proposed, which permits compact storage as well as easy hierarchical evaluation of the object. Finally, a tessellator for these multiresolution implicit objects is presented, that(More)