Thomson Licensing

Interdigital Vc Holdings, Inc.

Tldtv

Dolby International Ab

Interdigital Madison Patent Holdings, Sas

Interdigital Madison Patent Holdings

Wenfei Jiang

Kangying Cai

Jiang Tian

Zhibo Chen

Tao Luo

Fan Zhang

Teng Ge Ma

Ping Hu

Kai Xie

Yi Hu

Jian Jin

A method and an apparatus for constructing a spatial tree data structure corresponding to a region. According to the present principles, a cell may include therein a point or a set of points that are determined to be duplicate points. In an embodiment the duplicate points are determined based on the size of the points included within the cell. The inclusion of duplicate points within a particular cell, rather than further subdividing the cell, provides coding efficiency. The present principles are particularly advantageous in the context of quadtree or octree type partitioning, and may be used in 3D mesh coding.

Position coding based on spatial tree with duplicate points

A method and apparatus for position decoding of three dimensional mesh models are described including predicting a symbol probability of a non-empty-child-cell C, where Cdenotes the kcell at layer l, wherein the symbol probability is estimated based on an accuracy of a fitted plane P, decoding the non-empty-child-cell responsive to the received predicted probability of the non-empty-child-cell, subdividing the non-empty-child-cell, if the non-empty-child-cell has more than one vertex, determining if there are more unprocessed non-empty-child-cells at layer l, determining if a lowest layer of non-empty-child-cells has been reached, if there are no more unprocessed non-empty-child-cells at layer l and regenerating the three dimensional mesh model, if the lowest layer of non-empty-child-cells has been reached.

Predictive position decoding

The invention provides a method of terminable spatial tree-based position coding and decoding, and corresponding coding and decoding apparatus. The encoding method comprises: constructing a cell around the input spatial points; recursively dividing the cell into sub-cells at different layers; and assigning a symbol for each sub-cell indicating whether or not there is a spatial point within each sub-cell. The method further comprising: terminating further division of a sub-cell, if the sub-cell contains only one point and the distance between the center point of the sub-cell and the point contained in the sub-cell is smaller than the allowed maximal error.

Terminable spatial tree-based position coding and decoding

A 3D model can be modeled using 'pattern-instance?representation. To describe the vertices and triangles, properties of the instance, for example, texture, color, and normal, are adjusted to correspond to the order in the pattern. The texture of an instance is encoded depending on its similarity with the texture of a corresponding pattern. When instance texture is identical or almost identical to the pattern texture, the instance texture is not encoded and the pattern texture will be used to reconstruct the instance texture. When the instance texture is similar to the pattern texture, the instance texture is predictively encoded from the pattern texture, that is, the difference between the instance texture and pattern texture is encoded, and the instance texture is determined as a combination of the pattern texture and the difference.

Method and apparatus for compressing texture information of three-dimensional (3D) models

A 3D model can be modeled using 'pattern-instance' representation, wherein an instance component may be represented as transformation (for example, rotation, translation, and scaling) of a pattern. To improve compression efficiency, the quantization parameters for the rotation part and translation part for transformation of an instance can be determined based on the quantization parameter used for encoding a corresponding pattern. Specifically, the quantization parameter for the rotation part may depend on the size of the instance, and the quantization parameter for the translation part may depend on the scale of translation. That is, a larger instance may use a finer quantization parameter for the rotation part. The quantization parameters are so determined that quantization errors caused by compressing the patterns, the translation part of transformation, and the rotation part of transformation are at similar levels.

Method and apparatus for repetitive structure discovery based 3D model compression

A particular implementation forms an initial reconstructed image block from inverse quantization and inverse transform, and further refines the reconstructed image block using pixels from neighboring reconstructed blocks. The image block may be refined using a bilateral filter, whose space parameter and range parameter are adaptive to the quantization parameter. The particular implementation can be used in both encoding and decoding when reconstructing an image block. When used in encoding, the particular implementation can be used jointly with coefficient truncation, where some non-zero transform coefficients are set to zero. The number of remaining non-zero transform coefficients after coefficient truncation may be adaptive to the quantization parameter, the variance of the image block, the number of non-zero transform coefficients of the image block, and the index of the last non-zero transform coefficient in a zigzag scanning order.

Video encoding and decoding based on image refinement

A method and apparatus for generating a bitstream representative of a 3D model, and a method and an apparatus for processing the same. A 3D model is modeled by using a using a 'pattern-instance' representation, wherein a pattern is a representative geometry of a repetitive structure, and the connected components belonging to the repetitive structure is call an instance of the corresponding pattern. After discovery of the repetitive structures and their transformations and properties, the present embodiments provide for generating a bitstream in either a first format or a second format. In the first format, the pattern ID and its associated transformation and property information are grouped together in the bitstream, and in the second format the pattern ID, transformation property and property information are grouped together according to information type.

Method and apparatus for generating a bitstream of repetitive structure discovery based 3D model compression

A 3D model can be modeled using 'pattern-instance' representation, wherein an instance component may be represented as transformation (for example, rotation, translation, and scaling) of a pattern. Quantization errors may be introduced when encoding rotation information, causing different vertex coordinate errors at different 5 vertices of an instance. To efficiently compensate the vertex coordinate errors, the encoder decides a quantization parameter for compensating a vertex coordinate error. The quantization parameter is signaled in the bitstream as a quantization index. The quantization index, a quantization table the indicates a mapping between quantization indices and quantization parameters, and vertex coordinate errors are 10 encoded into a bitstream. The quantization table may be built based on statistical data. At the decoder, the vertex coordinate error is decoded based on a quantization parameter, which is determined from a received quantization index.

Method and apparatus for vertex error correction

Disclosed are a method and apparatus for processing a 3D model. To preserve fine structures while de-noising a 3D mesh model, the local structural information around a vertex is captured when designing a de-noising filter. In particular, for a current vertex to be processed, a path, for example, a geodesic path, is determined between the current vertex and each neighboring vertex. For each mesh edge along the path, local variations are calculated for the two end vertices of the mesh edge using a covariance matrix, and a geometric variation for the mesh edge is calculated as the difference between the two local variations. Then structural information for the region between the current vertex and a neighboring vertex is calculated as a function of the geometric variations for mesh edges along the path, for example, as the maximum geometric variation along the path. The present principles can also be adjusted to be used in de-noising 3D point-based models.

Method and apparatus for 3D mesh de-noising

A particular implementation decomposes an image into a structure component and a texture component. An edge strength map is calculated for the structure component, and a texture strength map is calculated for the texture component. Using the edge strength and the texture strength, texture masking weights are calculated. The stronger the texture strength is, or the weaker the edge strength is, the more distortion can be tolerated by human eyes, and thus, the smaller the texture masking weight is. The local distortions are then weighted by the texture masking weights to generate an overall distortion level or an overall quality metric.

Texture masking for video quality measurement

To reduce the entropy of occupancy codes of an octree and improve compression efficiency, the present principles provide a method and an apparatus for traversing sub-cells in a cell according to the geometrical property of 3D models. That is, a surface smoothness measure is calculated for each sub-cell and the sub-cells are traversed in a pre-determined order of surface smoothness measures. To compute the surface smoothness measure, a sub-cell is connected to neighboring cells of its parent cell to form triangles and angles. Subsequently, the triangle areas or angular measures are used to compute the surface smoothness measure. When the connectivity information is not available in the 3D model data, the present principles also provide a method and an apparatus for estimating the connectivity.

Efficient compression of 3D models based on octree decomposition

A 3D model can be modeled using pattern-instance representation, wherein an instance component may be represented as transformation (for example, rotation, translation, and scaling) of a pattern. Quantization errors may be introduced when encoding rotation information, causing different vertex coordinate errors at different vertices of an instance. To efficiently compensate the vertex coordinate errors, an upper bound can be estimated for the vertex coordinate error of a vertex. Based on the upper bound, the codec decides whether the vertex coordinate error of the vertex needs to be compensated, and decides a quantization parameter for compensating the vertex coordinate error if compensation is needed. The upper bound can be estimated at both the encoder and decoder, and thus, no explicit signaling is needed to indicate whether vertex coordinate error compensation is used or to indicate the quantization parameter for the vertex coordinate error.

Vextex correction method and apparatus for rotated three-dimensional (3D) components

In 3D mesh coding, the geometry data is compressed by spatial tree based approaches. Bitstreams that result from the traversal of a tree structure of spatial tree based approaches for encoding 3D mesh models have systematically special redundancies, which is exploited for further improving the mesh model compression. A method for encoding a bitstream comprises steps of defining at least a first and a second symbol group of binary symbols, with S1 being a subset of S2, determining within the bitstream first portions, second portions and third portions, wherein first portions have Th1 or more consecutive S1 symbols and second portions have Th2 or more consecutive S2 symbols, encoding the bitstream, wherein first portions, second portions and third portions are encoded using different codes, and encoding values indicating the boundary positions between the first, second and third portions in the bitstream.

Method for adaptive entropy coding of tree structures

The invention proposes modification of quantized coefficients for signalling of a post-processing method. Therefore, it is proposed a method for lossy compress-encoding data comprising at least one of image data and audio data. Said method comprises determining quantized coefficients using a quantization of a discrete cosine transformed residual of a prediction of said data. Said method further comprises modifying said quantized coefficients for minimizing rate-distortion cost wherein distortion is determined using a post-processed reconstruction of the data, the post-processed reconstruction being post-processed according to a postprocessing method, and compress-encoding said modified coefficients. In said proposed method, the post-processing method is that one of n&#x3e;1 different predetermined post processing method candidates whose position in an predetermined order of arrangement of the post processing method candidates equals a remainder of division, by n, of a sum of the modified coefficients. Doing so removes the overhead of flags in the bit stream.

Method and device for lossy encoding data and corresponding device for reconstructing data

A method and apparatus for position coding of three dimensional mesh models are described including estimating a symbol probability of a non-empty-child-cell Cwhere Qdenotes the kcell at layer l, wherein the symbol probability is estimated based on an accuracy of a fitted plane P, sub-dividing the non-empty-child-cell to produce a sub-cell, if the non-empty-child-cell has more than one vertex, determining if there are more unprocessed non-empty-child-cells at layer l, if there are no more unprocessed non-empty-child-cells at layer l, determining if all non-empty-child-cells at layer l have only one vertex and a distance between the center of the sub-cell and a point inside the sub-cell is less than or equal to a first threshold and entropy coding symbols representing a position of the non-empty-child-cells, if all non-empty-child-cells at layer l have only one vertex and the distance between the center of the sub-cell and the point inside the sub-cell is less than or equal to the first threshold.

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Beijing, China

Wenfei Jiang