CN-121986358-A - V-DMC displacement boost conversion

CN121986358ACN 121986358 ACN121986358 ACN 121986358ACN-121986358-A

Abstract

An apparatus for decoding encoded mesh data is configured to receive one or more syntax elements in a bitstream of encoded mesh data, determine an offset value based on the one or more syntax elements, determine a set of transform coefficients, apply an offset to the set of transform coefficients to determine an updated set of transform coefficients, inverse transform the updated set of transform coefficients to determine a set of displacement vectors, and determine a decoding mesh based on the set of displacement vectors.

Inventors

R. Huda
G. Van der oueira
A. Ahtar
A. K. RAMASU bramonian
M. Karchwitz

Assignees

高通股份有限公司

Dates

Publication Date: 20260505
Application Date: 20240912
Priority Date: 20240911

Claims (20)

1. An apparatus for decoding encoded mesh data, the apparatus comprising: memory, and Processing circuitry coupled to the memory and configured to: receiving one or more syntax elements in a bitstream of the encoded mesh data; Determining an offset value based on the one or more syntax elements; Determining a set of transform coefficients; Applying an offset to the set of transform coefficients to determine an updated set of transform coefficients; inverse transforming the updated set of transform coefficients to determine a set of displacement vectors, and A decoding grid is determined based on the set of displacement vectors.
2. The apparatus of claim 1, wherein to inverse transform the updated set of transform coefficients, the processing circuit is further configured to apply an inverse lifting transform.
3. The apparatus of claim 1, wherein to inverse transform the updated set of transform coefficients to determine the set of displacement vectors, the processing circuit is configured to inverse transform the updated set of transform coefficients to determine values of normal components of the set of displacement vectors.
4. The apparatus of claim 1, wherein to apply the offset to the set of transform coefficients to determine the updated set of transform coefficients, the processing circuit is configured to add the offset to each coefficient in the set of transform coefficients.
5. The device of claim 1, wherein to determine the decoding grid, the processing circuit is configured to: Determining a base mesh having a first set of vertices from the bitstream of the encoded mesh data; sub-dividing the base mesh to determine an additional set of vertices of the base mesh; Deforming the base mesh, wherein deforming the base mesh comprises modifying the positions of the additional vertex sets based on one or more displacement vectors, and The decoding grid is determined based on the deformed base grid.
6. The apparatus of claim 5, wherein the first set of vertices corresponds to a highest level of detail and the additional vertices correspond to a lower level of detail, and the processing circuitry is further configured to: determining a respective offset value for each of the lower levels of detail; Determining a respective set of transform coefficients for each of the lower levels of detail; Applying a respective offset for each of the lower levels of detail to the respective set of transform coefficients for each of the lower levels of detail to determine a respective updated set of transform coefficients for each of the lower levels of detail; Inverse transforming said respective updated set of transform coefficients for each of said lower detail levels to determine a respective set of displacement vectors for each of said lower detail levels, and The decoding grid is determined based on the respective set of displacement vectors for each of the lower levels of detail.
7. The apparatus of claim 6, wherein to determine the respective offset value for each of the lower levels of detail, the processing circuitry is further configured to receive a respective syntax for each of the lower levels of detail.
8. The device of claim 1, wherein to determine the set of transform coefficients, the processing circuit is configured to: receiving a set of quantized transform coefficients, and Dequantizing the set of quantized transform coefficients to determine the set of transform coefficients.
9. The device of claim 1, wherein the processing circuit is configured to: Extracting a displacement bit stream from said bit stream of said encoded grid data, and The one or more syntax elements in the shifted bitstream are received.
10. The apparatus of claim 1, the apparatus further comprising: A display configured to display the decoding grid.
11. A method of decoding encoded trellis data, the method comprising: receiving one or more syntax elements in a bitstream of the encoded mesh data; Determining an offset value based on the one or more syntax elements; Determining a set of transform coefficients; Applying an offset to the set of transform coefficients to determine an updated set of transform coefficients; inverse transforming the updated set of transform coefficients to determine a set of displacement vectors, and A decoding grid is determined based on the set of displacement vectors.
12. The method of claim 11, wherein inverse transforming the updated set of transform coefficients comprises applying an inverse lifting transform to the set of transform coefficients.
13. The method of claim 11, wherein inverse transforming the updated set of transform coefficients to determine the set of displacement vectors comprises inverse transforming the updated set of transform coefficients to determine values of normal components of the set of displacement vectors.
14. The method of claim 11, wherein applying the offset to the set of transform coefficients to determine the updated set of transform coefficients comprises adding the offset to each coefficient in the set of transform coefficients.
15. The method of claim 11, wherein determining the decoding grid comprises: Determining a base mesh having a first set of vertices from the bitstream of the encoded mesh data; sub-dividing the base mesh to determine an additional set of vertices of the base mesh; Deforming the base mesh, wherein deforming the base mesh comprises modifying the positions of the additional vertex sets based on one or more displacement vectors, and The decoding grid is determined based on the deformed base grid.
16. The method of claim 15, wherein the first set of vertices corresponds to a highest level of detail and the additional vertices correspond to lower levels of detail, and the method further comprises: determining a respective offset value for each of the lower levels of detail; Determining a respective set of transform coefficients for each of the lower levels of detail; Applying a respective offset for each of the lower levels of detail to the respective set of transform coefficients for each of the lower levels of detail to determine a respective updated set of transform coefficients for each of the lower levels of detail; Inverse transforming said respective updated set of transform coefficients for each of said lower detail levels to determine a respective set of displacement vectors for each of said lower detail levels, and The decoding grid is determined based on the respective set of displacement vectors for each of the lower levels of detail.
17. The method of claim 16, wherein determining the respective offset value for each of the lower levels of detail comprises receiving a respective syntax for each of the lower levels of detail.
18. The method of claim 11, wherein determining the set of transform coefficients comprises: receiving a set of quantized transform coefficients, and Dequantizing the set of quantized transform coefficients to determine the set of transform coefficients.
19. The method of claim 11, the method further comprising: Extracting a displacement bit stream from said bit stream of said encoded grid data, and The one or more syntax elements in the shifted bitstream are received.
20. An apparatus for encoding mesh data, the apparatus comprising: A memory; processing circuitry coupled to the memory and configured to: Determining a set of displacement vectors for the grid data; Transforming the set of displacement vectors to determine a set of transform coefficients; Determining a bias value for the set of transform coefficients; Determining an offset value based on the offset values of the set of transform coefficients; subtracting the offset value from the set of transform coefficients to determine offset-adjusted transform coefficients; quantizing the offset-adjusted transform coefficients to determine quantized coefficients, and The quantization coefficients and the indication of the offset are signaled in a bitstream of encoded mesh data.

Description

V-DMC displacement boost conversion The present application claims priority from U.S. patent application Ser. No. 18/882,516, filed on Ser. No. 2024, ser. No. 9, ser. No. 63/589,192, filed on Ser. No. 2023, ser. No. 10, and Ser. No. 63/590,679, filed on Ser. No. 2023, ser. No. 16, and U.S. provisional patent application Ser. No. 63/621,478, filed on Ser. No. 2024, 1, and 16, the entire contents of which are incorporated herein by reference. U.S. patent application Ser. No. 18/882,516 claims the benefits of U.S. provisional patent application Ser. No. 63/589,192, U.S. provisional patent application Ser. No. 63/590,679, and U.S. provisional patent application Ser. No. 63/621,478. Technical Field The present disclosure relates to video-based dynamic trellis coding. Background The grid may be used to represent the physical content of a three-dimensional space. The grid may have utility in a variety of situations. For example, grids may be used in the context of physical content representing an environment in order to locate virtual objects in an augmented reality (e.g., augmented Reality (AR), virtual Reality (VR), or Mixed Reality (MR)) application. Grid compression is a process for encoding and decoding a grid. Encoding the trellis may reduce the amount of data required to store and transmit the trellis. Disclosure of Invention The technology of the present disclosure relates to video-based dynamic grid coding (V-DMC), and more particularly to signaling of displacement vectors. As will be explained in more detail below, the V-DMC encoder may be configured to transform the values of the displacement vector, for example, using a wavelet transform employing a lifting scheme, to generate a set of transform coefficients corresponding to a certain dimension (e.g., X, Y or Z) of the transform coefficients. But the lifting scheme may introduce a bias into the transform coefficients. In this context, offset means that the average of the values resulting from the lifting transform is not zero. In accordance with the techniques of this disclosure, a V-DMC encoder may be configured to determine an offset in a transform coefficient, determine an offset based on the offset, and subtract the offset from the transform coefficient to determine an offset-adjusted transform coefficient. In most coding scenarios, the bias adjustment causes the bias adjusted transform coefficients to have more values that are at or near zero and reduces the average magnitude of these values. The video encoder may then quantize the offset-adjusted transform coefficients (rather than the original transform coefficients). By having more values equal or close to zero, these values can be signaled with fewer bits and reduce quantization errors, thereby improving the overall rate-distortion tradeoff achieved by the encoding and decoding process. The V-DMC encoder may also signal to the V-DMC decoder an indication of the offset value used in the encoding process. Thus, after the V-DMC decoder dequantizes the offset-adjusted transform coefficients, the V-DMC decoder may add an offset to the dequantized offset-adjusted transform coefficients, thereby substantially adding the offset and obtaining a decoded version of the original transform coefficients. Since the quantization and dequantization processes may be lossy, the decoded version of the original transform coefficients may not exactly match the original transform coefficients determined by the V-DMC encoder. The V-DMC decoder may then inverse transform the transform applied by the V-DMC encoder, e.g., inverse transform a wavelet transform employing a lifting scheme, to determine a decoded version of the displacement vector. While the techniques of this disclosure may be applied to any component of a displacement vector, it is observed that the described techniques may be particularly beneficial when applied to the normal component of a normal vector (generally identified as the x-component). According to an example of the present disclosure, an apparatus for decoding encoded mesh data includes a memory, a processing circuit coupled to the memory and configured to receive one or more syntax elements in a bitstream of the encoded mesh data, determine an offset value based on the one or more syntax elements, determine a set of transform coefficients, apply an offset to the set of transform coefficients to determine an updated set of transform coefficients, inverse transform the updated set of transform coefficients to determine a set of displacement vectors, and determine a decoding mesh based on the set of displacement vectors. In accordance with an example of the present disclosure, a method of decoding encoded mesh data includes receiving one or more syntax elements in a bitstream of the encoded mesh data, determining an offset value based on the one or more syntax elements, determining a set of transform coefficients, applying an offset to the set of transform coefficients to determine an updated s