Depth Mesh Warping for Low-Latency AR Rendering
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Solution Overview
Problem
Existing artificial reality systems face challenges in rendering moving objects with low latency, particularly when offloading rendering to a server due to limited computing power in head-mounted devices (HMDs).
Innovation Solution
The system warps a depth mesh associated with an object by providing metadata for vertices in the mesh to the HMD. This involves receiving a color texture and a depth mesh from a server, warping the depth mesh using metadata and motion data, and rendering frames using the warped mesh and color texture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If rendering is offloaded to a server, then rendering capability is improved, but latency increases
Solution Approach 1:
The rendering process is segmented into two parts: static mesh rendering is performed on the server, while dynamic mesh warping is performed locally on the HMD. This segmentation allows the server to handle computationally intensive tasks without real-time latency constraints, while the HMD handles time-critical warping operations locally, thus resolving the contradiction between rendering capability and latency.
Solution Approach 2:
The server performs preliminary rendering of the static mesh and generates depth maps in advance. These pre-rendered elements are then transmitted to the HMD, which applies real-time warping based on motion data. This preliminary action reduces the computational burden during real-time rendering, thereby reducing latency while maintaining high rendering quality.
2Weight of stationary object
If the HMD has limited computing power, then device weight and complexity are reduced, but rendering performance deteriorates
Solution Approach 1:
The computationally intensive rendering tasks are extracted from the HMD and offloaded to an external server. The HMD retains only the essential functions of receiving rendered meshes, processing motion data, and performing lightweight mesh warping. This extraction allows the HMD to maintain low weight and simplicity while achieving high rendering performance through cloud computing assistance.
Solution Approach 2:
A server acts as an intermediary between the content source and the HMD. The server performs heavy rendering computations and sends processed mesh data to the HMD, which then applies local warping transformations. This intermediary architecture enables the HMD to achieve high rendering performance without requiring substantial local computing power, thus maintaining lightweight design.
3Speed
If real-time mesh warping is performed on the HMD, then rendering timeliness is improved, but computational load on HMD increases
Solution Approach 1:
Instead of performing complete re-rendering of the entire scene, the system applies partial warping transformations only to the dynamic portions of the mesh based on motion data. This partial action approach achieves real-time rendering timeliness by updating only the necessary portions of the scene, thereby minimizing the computational load and energy consumption on the HMD.
Data Source
AI summary
A method for rendering a frame includes receiving, from a server, a color texture and a depth mesh associated with an object to be rendered, the depth mesh including multiple vertices and metadata associated with the vertices. The method further includes receiving motion data associated with the object, warping the depth mesh using the metadata and the motion data, resulting in a warped depth mesh, and rendering one or more frames using the color texture and the warped depth mesh.