Abstract: A method is disclosed to generate (u,v) coordinates at the decoder side by using parameters of orthographic projection functions, transmitted via an atlas bitstream. With the parameters for orthographic projection, the decoder is able to efficiently generate (u,v) coordinates and avoid their expensive coding.

Abstract: The generation of a texture map using orthographic projections is performed in a fast and efficient manner. A method to generate texture maps taking significantly less time and also allowing maps to exploit the correlation between content of different frames in time is described herein. The texture mapping is able to be used for automatic generation of volumetric content or for more efficient compression of dynamic meshes. The texture map generation described herein includes ways to generate a texture atlas using orthographic projections. A novel stretch metric for orthographic projections is described, and a merging algorithm is devised to optimally cluster triangles into a single patch. Additionally, packing techniques are able to be used for mesh patches that try to optimize size and temporal stability.

Abstract: A method of compressing meshes using a projection-based approach, leveraging and expanding the tools and syntax generated for projection-based volumetric content compression is described. The mesh is segmented into surface patches, with the difference that the segments follow the connectivity of the mesh. The dense mesh compression utilizes 3D surface patches to represent connected triangles on a mesh surface and groups of vertices to represent triangles not captured by surface projection. Each surface patch (or 3D patch) is projected to a 2D patch, whereby for the mesh, the triangle surface sampling is similar to a common rasterization approach. For each patch, position and connectivity of the projected vertices are kept. The sampled surface resembles a point cloud and is coded with the same approach used for point cloud compression. The list of vertices and connectivity per patch is encoded, and the data is sent with the coded point cloud data.

Abstract: A method of compression of 3D mesh data using projections of mesh surface data and video representation of connectivity data is described herein. The method utilizes 3D surface patches to represent a set of connected triangles on a mesh surface. The projected surface data is stored in patches (a mesh patch) that is encoded in atlas data. The connectivity of the mesh, that is, the vertices and the triangles of the surface patch, are encoded using video-based compression techniques. The data is encapsulated in a new video component named vertex video data, and the disclosed structure allows for progressive mesh coding by separating sets of vertices in layers, and creating levels of detail for the mesh connectivity. This approach extends the functionality of the V3C (volumetric video-based) standard, currently being used for coding of point cloud and multiview plus depth content.

Abstract: Ways to improve mesh reconstruction by modifying the position of vertices at the border of patches to make sure that neighboring patches do not have a gap between them, also known as zippering, are described herein. Six different methods to implement the post-processing operation, as well as syntax elements and semantics for transmission of the filter parameters, are disclosed. A hierarchical method indicate the geometry distortion that can generate gaps between patches. The value per frame, or per patch, or per boundary object is sent. The number of bits to encode the values is also dependent on the previous geometry distortion. A method sends index matches instead of geometry distortion. The matching index is sent per boundary vertex, but a method to send only one index of the pair is implemented as well.

Abstract: Ways to post-process a decoded mesh and modify received triangles per patch to improve the mesh geometry are described herein. Since the transmitted geometry contains the high-resolution surface information, the information is able to be applied to the mesh reconstruction operation to generate triangles that are aligned with the original surface. Methods include generating new triangles by splitting the received triangles' edges according to their size, by inserting new vertices at the triangle's centroids, by splitting the vertices, and by performing marching cubes in surfaces defined by the geometry images.

Abstract: New syntax elements are used to extend patch types, and the syntax is added to the V3C standard. The new syntax defines patches that encode meshes by projecting connected triangles to a 2D surface, patches that encode triangles or triangle strips without any projection, or patches that are tracked over time and are encoded by projecting connected triangles to a 2D surface. Furthermore, the syntax allows for different ways of coding the mesh-specific information. For instance, the syntax enables three different encoding methods for the vertex position: explicit (directly added to the atlas stream), embedded on video data (occupancy map data), or encoded using an external mesh encoder.

Abstract: Ways to simplify connectivity data for patches are described herein. The patches are generated considering the high-resolution mesh information. The connectivity data is simplified at the patch level, while the geometry image is still preserved. For the connectivity simplification, only triangles inside the patch are simplified. If the border is still preserved, the reconstruction in 3D will not suffer from artifacts. The high-resolution geometry image can be used to reverse the simplification and improve the connectivity at the decoder side. Three embodiments of patch mesh simplification are described: quadric error edge collapse, border distance edge collapse, and border triangles only.

Abstract: The connectivity information and mapping information of a mesh surface patch are able to be encoded after projection to 2D. Regarding the connectivity information, the projection operation does not change the connection between vertices, so the same list of connected vertices are able to be carried in the atlas data. Similarly, the mapping information does not change after projection and is able to be carried in the atlas data. Two methods are disclosed for encoding the connectivity and mapping information. For the connectivity information, a video-based method uses neighboring color coding. For mapping coordinates, a method uses the projected vertex position. The connectivity and mapping are also able to be processed by an external mesh encoder. Newly proposed mapping information is able to be taken advantage of to perform temporal compression.

Abstract: Depth image generation is improved by more efficient encoding using video codecs. The mapping of the depth to the luma channel is performed by not using all bits available, and with the remaining bits, a depth scaling factor is generated and incorporated into the bilinear interpolation algorithm used during rasterization. A normal filtering procedure is described, where the positions of vertices are adjusted according to the normal estimated from the surface pixels. After decoding the depth image, the pixels related to the surface of a triangle are collected and used to estimate a plane and the normal of the plane. The normal is compared to the normal obtained from the plane defined by the three vertices of the triangle. If there is no match, the positions of the vertices are adjusted to match the estimated normal from the pixels' surfaces. The adjustment can follow an iterative minimization process.

Abstract: An architecture includes new blocks that transform mesh connectivity to enable lossy compression. In addition, a method generates surface patches from meshes and preserves the overall aspect of the object, while generating patches for efficient encoding using the V3C standard. Triangles are joined together into connected components, and conditional projection of each triangle to the surface is performed to enforce connectivity at the projected surface. A new depth filtering algorithm is able to be used to improve compression performance. The new blocks added for connectivity compression and the techniques introduced to ensure 2D connectivity to allow for UV texture map transmission and to filter depth values and avoid highfrequency edges in the depth image are described herein.

Abstract: A method and Video-Based Point Cloud Compression (V-PCC) decoder for synchronization of decoded frames before point cloud reconstruction is provided. A V-PCC bit-stream which includes encoded frames associated with a point cloud sequence is received. Sub-streams of the received V-PCC bit-stream are decoded by a group of video decoders of the V-PCC decoder to generate V-PCC components, such as an attribute component, a geometry component, an occupancy map component, and an atlas component. A release of the attribute component, the geometry component, the occupancy map component, and the atlas component to the reconstruction unit is delayed based on a first output delay, a second output delay, a third output delay, and a fourth output delay, respectively. The delayed release synchronizes the attribute component, the geometry component, the occupancy map component, and the atlas component with each other before the reconstruction unit reconstructs a point cloud based on the V-PCC components.

Abstract: An electronic device and method for adaptive mode selection for point cloud compression, is provided. The electronic device receives a 3D point cloud geometry and partitions the 3D point cloud geometry into a set of 3D blocks. For a 3D block of the set of 3D blocks, mode decision information is determined. The mode decision information includes class information of the 3D point cloud geometry, operational conditions associated with an encoding stage of the 3D point cloud geometry, or mode-related information associated with one or more 3D blocks of the set of 3D blocks. Based on the mode decision information, one or more modes are selected for the 3D block from a plurality of modes. Each mode corresponds to a function that is used to encode the 3D block. The 3D block is encoded based on the one or more modes.

Abstract: A method of mapping 3D point cloud data into 2D surfaces for further efficient temporal coding is described herein. Point cloud global tetris packing utilizes 3D surface patches to represent point clouds and performs temporally consistent global mapping of 3D patch surface data into 2D canvas images.

Abstract: Methods, systems and devices described herein implement a task-driven machine learning-based compression scheme for point cloud geometry implicit representation. The machine learning-based codec is able to be optimized for a task to achieve better compression rates by being conditioned to what the reconstructed signal will be used for. The latent representation of the point cloud or the neural network that implicitly represents the point cloud itself are able to be compressed. The methods described herein perform efficient compression of the implicit representation of a point cloud given a target task.

Abstract: Methods, systems and device for efficiently compressing task-oriented dynamic meshes using occupancy networks are described herein. A single trained occupancy network model is able to reconstruct a mesh video using a few additional points per input mesh frame. To optimize the compression of the model and points, the estimated rate to compress the occupancy network is able to be included in the loss function. This minimizes the number of bits to encode the model, while it tries to reproduce the meshes as well as possible. An adaptive subsampling per input mesh is added to optimize the mesh reconstruction and the N-point point clouds compression. To optimize the model to perform a particular task, a metric is added to the cost function that takes this task into account.

Abstract: Occupancy networks enable efficient and flexible point cloud compression. In addition to the voxel-based representation, occupancy networks are able to handle points, meshes, or projected images of 3D objects, making them very flexible in terms of input signal representation. The probability of occupancy of positions is estimated using occupancy networks instead of sparse convolutional neural networks. A compression implementation using occupancy network enables scalability with infinite reconstruction resolution.

Abstract: A method of motion compensation for geometry representation of 3D data is described herein. The method performs motion compensation by first identifying correspondent 3D surfaces in time domain, then followed by a 3D to 2D projection of motion compensated 3D surface patches, and then finally performing 2D motion compensation on the projected 3D surface patches.

Abstract: An apparatus and method for three-dimensional (3D) geometric data compression, includes storage of a first 3D geometric mesh of a first data size, which includes a 3D representation of a plurality of objects in a 3D space. The apparatus includes circuitry that receives motion tracking data of the plurality of objects from a plurality of position trackers. The motion tracking data includes motion information of each of the plurality of objects from a first position to a second position in the 3D space. The 3D geometric mesh is segmented into a plurality of 3D geometric meshes corresponding to the plurality of objects, based on the motion tracking data. As a result of the segmentation of the 3D geometric mesh before encoding and the use of motion tracking data, the plurality of 3D geometric meshes are efficiently encoded.

Abstract: A method for reducing color leaking artefacts in an image formed by projection processing from a 3D point cloud comprises: receiving an input image comprising the 3D point cloud; classifying the cloud into a plurality of surface patches; projecting the patches onto a plane to form a first 2D image; processing the first 2D image, by coding, transmitting and decoding, to form a final 2D image; and providing the final 2D image as an output. Processing includes independent patch processing to reduce inter-patch color leakage in the final 2D image, the independent patch processing including chroma sub-sampling pixels within each of the projected patches in the first 2D image separately; recombining the chroma sub-sampled patches to form a second 2D image; and compressing the second 2D image.