Systems and methods for reflection symmetry-based mesh coding
The various implementations described herein include methods and systems for encoding video. In one aspect, a method includes receiving a mesh with polygons representing a surface of an object; detecting a first symmetric region in the mesh that includes a first symmetry line to divide the first symmetric region into a first partition and a second partition. The method includes recursively determining whether one of the first partition or the second partition includes a second symmetric region until no symmetric region is detected in both the first partition and the second partition. The method includes in response to detecting the second symmetric region within one of the first partition or the second partition: determining a second symmetry line within the second symmetric region to divide the first or the second partition into a third sub-partition and a fourth sub-partition; and compressing information of the third sub-partition, the second symmetry line and the first symmetry line into a bitstream.
1 . A method for encoding a mesh performed by a computing system having memory and one or more processors, the method comprising:
receiving a mesh with polygons representing a surface of an object;
detecting a first symmetric region in the mesh comprising a first symmetry line to divide the first symmetric region into a first partition and a second partition;
recursively determining whether one of the first partition or the second partition includes a second symmetric region until no symmetric region is detected in both the first partition and the second partition;
in response to detecting the second symmetric region within one of the first partition or the second partition: determining a second symmetry line within the second symmetric region to divide the first or the second partition into a third sub-partition and a fourth sub-partition; and
compressing information of the third sub-partition, the second symmetry line and the first symmetry line into a bitstream, wherein a reflected vertex is a vertex of the first partition that is reflected about the first symmetry line, and the reflected vertex and a corresponding vertex from the second partition has a first displacement, and the method includes compressing information about the first displacement into the bitstream.
2 . The method of claim 1 , further comprising:
compressing a first set of information about the third sub-partition into the bitstream.
3 . The method of claim 1 , further comprising:
prior to detecting the first symmetric region, partitioning the mesh into a first symmetric portion and a second asymmetric portion, wherein detecting the first symmetric region in the mesh comprises determining the first symmetry line, and compressing information of the second asymmetric portion into the bitstream.
4 . The method of claim 3 , wherein partitioning the mesh into the first symmetric portion and the second asymmetric portion further comprises:
in accordance with a determination that the mesh includes one or more non-connected mesh components, separating the mesh into respective non-connected mesh components.
5 . The method of claim 1 , wherein compressing the information about the first symmetry line into the bitstream comprises encoding a set of vertices of the first partition.
6 . The method of claim 1 , further comprising:
reconstructing the mesh using the first symmetry line and information about a normal direction of the first symmetry line, a distance of an encoded vertex from the first symmetry line.
7 . The method of claim 1 , wherein determining the first symmetry line comprises determining a first symmetry plane containing the first symmetry line, and wherein compressing the information about the first symmetry line into the bitstream comprises encoding the first symmetry plane.
8 . The method of claim 7 , wherein the first symmetry plane is encoded using a symmetry pair of vertices comprising a first vertex and a second vertex such that a reflection of the first vertex about the first symmetry plane provides the second vertex.
9 . The method of claim 8 , wherein the first vertex of the symmetry pair of vertices is encoded in mesh data or is signaled with the first symmetry plane.
10 . The method of claim 7 , wherein the first symmetry plane is modelled using a linear equation having four parameters that are signaled.
11 . The method of claim 1 , further comprising: providing a displacement vector comprising respective displacements between a set of vertices of the first partition and a corresponding set of vertices of the second partition, and the method includes compressing information about the displacement vector into the bitstream.
12 . The method of claim 1 , wherein the first partition and the second partition comprise an almost symmetric mesh.
13 . The method of claim 1 , wherein the first line of symmetry is a reflectional plane of symmetry.
14 . A computing system, comprising:
control circuitry;
memory; and
one or more sets of instructions stored in the memory and configured for execution by the control circuitry, the one or more sets of instructions comprising instructions for:
receiving a mesh with polygons representing a surface of an object;
detecting a first symmetric region in the mesh comprising a first symmetry line to divide the first symmetric region into a first partition and a second partition;
recursively determining whether one of the first partition or the second partition includes a second symmetric region until no symmetric region is detected in both the first partition and the second partition;
in response to detecting the second symmetric region within one of the first partition or the second partition: determining a second symmetry line within the second symmetry region to divide the first or the second partition into a third sub-partition and a fourth sub-partition; and
compressing information of the third sub-partition, the second symmetry line and the first symmetry line into a bitstream, wherein a reflected vertex is a vertex of the first partition that is reflected about the first symmetry line, and the reflected vertex and a corresponding vertex from the second partition has a first displacement, and the instructions includes instructions for compressing information about the first displacement into the bitstream.
15 . The computing system of claim 14 , wherein the one or more sets of instructions further comprises instructions for compressing a first set of information about the third sub-partition into the bitstream.
16 . The computing system of claim 14 , wherein the one or more sets of instructions further comprise instructions for, prior to determining a symmetry plane of the mesh, partitioning the mesh into a first symmetric portion and a second asymmetric portion, wherein determining the symmetry plane of the mesh comprises determining a symmetry plane of the first symmetric portion, and compressing information of the second asymmetric portion into the bitstream.
17 . A non-transitory computer-readable storage medium storing one or more sets of instructions configured for execution by a computing device having control circuitry and memory, the one or more sets of instructions comprising instructions for:
receiving a mesh with polygons representing a surface of an object;
detecting a first symmetric region in the mesh comprising a first symmetry line to divide the first symmetric region into a first partition and a second partition;
recursively determining whether one of the first partition or the second partition includes a second symmetric region until no symmetric region is detected in both the first partition and the second partition;
in response to detecting the second symmetric region within one of the first partition or the second partition: determining a second symmetry line within the second symmetry region to divide the first or the second partition into a third sub-partition and a fourth sub-partition; and
compressing information of the third sub-partition, the second symmetry line and the first symmetry line into a bitstream, wherein a reflected vertex is a vertex of the first partition that is reflected about the first symmetry line, and the reflected vertex and a corresponding vertex from the second partition has a first displacement, and the instructions includes instructions for compressing information about the first displacement into the bitstream.
18 . The non-transitory computer-readable storage medium of claim 17 , wherein the one or more sets of instructions further comprises instructions for compressing a first set of information about the third sub-partition into the bitstream.
19 . The non-transitory computer-readable storage medium of claim 17 , wherein the one or more sets of instructions further comprise instructions for, prior to determining a symmetry plane of the mesh, partitioning the mesh into a first symmetric portion and a second asymmetric portion, wherein determining the symmetry plane of the mesh comprises determining a symmetry plane of the first symmetric portion, and compressing information of the second asymmetric portion into the bitstream.