Orange

France Telecom

Fondation B Com

Telediffusion De France

B-com

Patrick Gioia

Antonin Gilles

Kartik Viswanathan

Shasha Shi

Remi Cozot

Luce Morin

Jérôme Baril

Jérôme Royan

Romain Cavagna

Disclosed is a method for constructing a digital hologram to be displayed by of a display system. The display system includes a light modulator producing a light beam and a convergent optical device designed to make the light beam converge towards a focal point. The scene is defined by a set of luminous elements. The construction method includes a step of determining values respectively associated with the pixels of the digital hologram by summing the light contributions respectively produced by the luminous elements with weighting, for each of the light contributions, by a correction coefficient depending on the area of the intersection of a surface between the convergent optical device and the focal point, and a pencil of light having a predetermined angular opening and transmitted through the convergent optical device from the luminous element producing the light contribution concerned. An associated holographic system is also described.

Method for constructing a digital hologram and associated digital holography system

Disclosed is a method and a device for coding a sequence including first and second digital holograms representing respective scenes, the digital holograms being represented by a set of wavelets each defined by a multiplet of coordinates in multidimensional space. The first and second holograms are represented by first and second coefficients respectively associated with wavelets. The coding method includes the following steps: for each second coefficient, determining a remainder by a difference between the second coefficient concerned, associated with a first wavelet defined by a given multiplet, and the first coefficient) associated with a second wavelet defined by a multiplet having as its image the multiplet by a transform in the multidimenisonal space; coding the determined remainders. The transform is determined by analysis of variation between the first scene represented by the first digital hologram and the second scene represented by the second digital hologram.

Method and device for coding a digital hologram sequence

Disclosed is a method for processing an input hologram HE associated with an input plane, to obtain an output hologram displayable on a holographic screen placed in a plane called the output plane of a display system, viewable from a viewing plane of the system. The method includes: receiving the input hologram and a position of the input plane; obtaining a first transfer matrix representative of a propagation between the input plane and the viewing plane; obtaining a second transfer matrix representative of a propagation between the viewing plane and the output plane; calculating an overall matrix of transfer of a light field emitted by the input hologram, between the input plane and the output plane, by taking the product of the two matrices; and converting the input hologram into the output hologram by applying an operator dependent of the input hologram and on the screen.

Method for processing a hologram, and associated device, holographic display system and computer program

Disclosed is a method for generating a digital hologram representing a 3D scene including an object, an object being defined by points and their associated intensity. For each object, a prior step of calculating an 'omnidirectional' angular spectrum of the light field emitted by an object in the scene on the surface of a geometric solid centered on the object, a surface of the solid being sampled according to a predetermined grid, a sample of the grid being associated with a vector frequency; for the scene, the following steps: &#x2014;obtaining a pose of an observer in the world frame of reference; &#x2014;deriving the hologram from the scene as a function of the pose obtained from the 'multidirectional' angular spectra calculated for each object. The step of calculating an angular spectrum of the light field for each object of the scene takes into account predetermined viewing directions.

Method for generating a digital hologram, associated device, holographic display system and computer program

Disclosed is a method for digitally generating a hologram in a screen plane of a hologram display device, including: obtaining intensity and depth maps of the scene corresponding to user viewpoint; projecting the points of the intensity map on planes parallel to the screen plane in a reference frame of the screen, one plane associated with one depth value of between minimum and maximum values of the depth map, a point of the intensity map projected on the plane of the planes associated with the depth value of the point in the depth map; compensating for distortion by modifying the planes of the scene, a point of one plane, called image point of an object point by conjugation of the convergent lens, being replaced by the object point; from the modified planes, propagating a complex sampled light wave to the screen plane and summation of the propagated light waves.

Method for digitally generating a hologram, device, terminal device, associated system and computer program

A method for processing a sequence of holographic images with a view to playing the images back on a holographic display device to at least one viewer. A subset of wavelet coefficients relevant for the reconstruction of a sub-hologram visible for the at least one viewer from at least one viewing point is selected from a decomposition of at least one holographic image on a wavelet basis and information representative of a location of the at least one viewer in a repository of the display device. In the method, decomposition of the at least one holographic image is carried out on a Shannon wavelet basis.

Method for processing a holographic image

A method for digitally generating a hologram plane from a three-dimensional scene, cut into a plurality of planes parallel to the hologram plane. The method includes for a current plane: counting a number of points of the non-zero amplitude scene; choosing a first or second technique for propagating a light wave emitted by the current plane as a function of a number of points of non-zero amplitude included in the current plane and with a preset threshold value, the first, point-based technique calculating the propagation of a sum of light waves emitted by point sources constituted by the points of the scene portion of a non-zero amplitude of the current plane on a following plane, and the second, field-based technique, globally calculating a light wave emitted by the scene portion situated in the current plane on a given plane; and processing the current plane according to the chosen propagation technique.

Method for digitally generating a hologram, related device and computer program

A method for processing a sequence of holographic images, with a view to its rendition by a holographic display device to at least one observer. A holographic image is decomposed over a Gabor wavelet basis into a set of wavelet coefficients. The method includes the following acts, implemented for an image of the sequence: obtaining items of information representative of the decomposition over the Gabor wavelet basis; obtaining of items of information representative of a location of the at least one observer in a reference frame of the display device; selecting a subset of wavelet coefficients as a function of the wavelet items of information and of the location items of information obtained.

Method for processing a sequence of holographic images, devices, signals, devices and computer program associated therewith

A method is provided for encoding at least one integral image representative of at least one object in perspective in a scene. The method implements the following steps: applying a discrete wavelet transform directly to the pixels of the integral image, delivering a plurality of transform coefficients; and encoding the delivered transform coefficients.

Method of coding and decoding integral images, a device for coding and decoding integral images, and corresponding computer programs

An encoder and method of encoding are provided for encoding at least one integral image representing at least one object in perspective in a scene and including a plurality of elemental images. The method of encoding includes generating a plurality of K sub-images on the basis of the plurality of basic images; arrangement of the sub-images in a predetermined pattern such as to form a multi-view image of the object, the views corresponding respectively to the sub-images; and adaptive compression of the multi-view image formed, as a function of the motion type of the object in the scene.

Method for encoding and decoding integral images, device for encoding and decoding integral images and corresponding computer programs

A method for coding at least one holographic pattern recording a light signal representative of light received by a perspective object in a scene. The method includes: determining, from the light signal and for each point x(1&#x2266;j&#x2266;M) of the holographic pattern, a set of N light rays passing through the point and corresponding respectively to N different viewing positions for viewing the pattern; generating from the M sets of N determined light rays, a plurality N of two-dimensional views of the object corresponding respectively to the N viewing positions of the pattern, by causing M determined rays to intersect at each of the viewing positions that are contained in a viewing plane parallel to a plane containing the holographic pattern; arranging the N generated views as a multi-view image of the object, the N views corresponding respectively to sub-images of the multi-view image; and compressing the multi-view image.

Method of coding a holographic pattern, a corresponding coding device and computer program

A method is provided for representing a material by approximating an original function modeling the interaction of the material and of light emitted by a light source, which function is defined as a function of pixels, of viewpoints, and of light directions, the method comprising: for each viewpoint, the steps of performing a polynomial approximation of the original modeling function and a geometric approximation of a residue resulting from the difference between the original modeling function and the polynomial approximation of said function; and a step of simplification by decomposing the results obtained from the two approximations into wavelet packets.

Method of representing a material

A technique is provided for transmitting a roof structure for constructing a three-dimensional representation of a building, via a communication network. The technique is based on the transmission of an ordered list of at least two roof models, each including at least: one type of roof; one maximum height parameter of the roof. During construction of the three-dimensional representation of a building, the maximum height parameter of a roof of the list determines a base of the roof in accordance with the list, so that the roof structure corresponds to the ordered superimposition of the roods of the list.

Methods, devices and programs for transmitting roof and building structure of a 3D representation of a building roof based on said structure

A method is provided for decoding a data stream representing an object with at least three dimensions, associated with a basic mesh including of an assembly of facets defined by an assembly of vertices and ridges, and with wavelet coefficients corresponding to the local modifications of the basic mesh, indexed each by a vertex of the basic mesh. For at least some wavelet coefficients of the data stream, the method includes the following steps: determining an orientation of an edge bearing the vertex indexing the wavelet coefficients, called an orientation of the wavelet coefficient; and determining, based on the orientation, information for locating in the basic mesh at least one child of the wavelet coefficient, distinct locating rules being associated with each orientation, so as to extract a data stream of at least some of the wavelet coefficients, associated each with locating information.

Method for locally decoding a bitstream of wavelet coefficients

The invention relates to a method for the coding an object having at leas two dimensions which is associated with a basic mesh comprising a set of basic surfaces and with coefficients in a base of wavelets corresponding to local modifications to said basic mesh. The inventive method delivers a global data flow that can be used to reconstruct the object. According to the invention, said wavelet coefficients are partitioned into at least two disjoint subsets each of which is encoded independently. Subsequently, positional data are inserted by the method into the global data flow which can be used to locate wavelet coefficients relative to a portion of the object in said global data flow, in such a way to enable a selective reconstruct of said portion using the coefficients of at least one said subsets.

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Servon sur Vilaine, France

Patrick Gioia