OctField Hierarchical Octree for 3D Shape Modeling

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Solution Overview

Problem

Current 3D deep learning methods face challenges in capturing fine geometric details, scalability, and efficient encoding of shape priors while maintaining a compact memory footprint and high computational efficiency, particularly due to the cubic growth of memory and computational costs with regular subdivision of 3D space.

Innovation Solution

The OctField method employs a hierarchical octree structure to adaptively allocate local implicit functions based on surface occupancy and geometry richness, using a differentiable hierarchical encoder-decoder network to learn both the octree structure and geometry features, thereby optimizing memory and computation usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If regular subdivision of 3D space is employed to capture fine geometric details, then modeling precision is improved, but memory footprint and computational cost increase cubically

Engineering Contradiction:
Improvemodeling precisionVSAvoidmemory footprint
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent divides the 3D space into a hierarchical octree structure, segmenting the space into octants at multiple levels. This allows selective refinement of only those regions containing geometric details, rather than uniformly subdividing the entire space. The segmentation enables memory-efficient representation by allocating resources only where needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by assigning different levels of detail to different regions of 3D space based on their geometric complexity. Regions with intricate surfaces receive finer subdivision and more computational resources, while empty or simple regions use coarser representation. This localized approach optimizes the balance between modeling precision and memory consumption.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If regular subdivision of 3D space is employed to capture fine geometric details, then modeling precision is improved, but computational cost increases cubically

Engineering Contradiction:
Improvemodeling precisionVSAvoidcomputational cost
Core Design Contradiction:
Measurement precisionVSPower

Solution Approach 1:

The hierarchical octree structure segments the computational domain into manageable octants, allowing the system to process only relevant regions. By dividing the space adaptively, the computational cost scales with the complexity of the geometry rather than the total volume, significantly reducing overall computational requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by performing detailed processing only on octants that contain geometric features, rather than processing the entire 3D space uniformly. This selective approach computes exactly what is necessary for accurate modeling without wasting computational resources on empty or simple regions.

Inventive Principle:
Principle #16Partial or excessive action

3Adaptability or versatility

If localized implicit functions are used to handle arbitrary topologies, then adaptability is improved, but memory footprint grows cubically with input volume

Engineering Contradiction:
Improvehandling arbitrary topologiesVSAvoidmemory footprint
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent combines localized implicit functions with hierarchical octree segmentation, allowing the system to handle arbitrary topologies while maintaining memory efficiency. Each octant contains a localized implicit function that adapts to local geometry, and the hierarchical structure ensures that memory is allocated only to octants that actually contain geometric features.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic adaptability by allowing the octree structure to be learned and modified during training. The system dynamically adjusts the subdivision level and octant boundaries based on the specific geometry being modeled, enabling efficient handling of diverse topologies without predetermined memory allocation.

Inventive Principle:
Principle #15Dynamics

4Quantity of substance

If octree structure is used for hierarchical representation, then memory efficiency is improved, but differentiability is lost due to discrete nature

Engineering Contradiction:
Improvememory efficiencyVSAvoiddifferentiability
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent transforms the discrete octree construction process into a continuous, differentiable one by reformulating the subdivision decisions as parameter optimization problems. Instead of discrete yes/no decisions about whether to subdivide, the system uses continuous parameters that can be optimized via gradient descent, enabling end-to-end training while maintaining memory efficiency.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional mechanical/discrete octree construction mechanism with a learned, differentiable neural network-based approach. The network predicts octree structure and implicit function parameters in a continuous manner, substituting the discrete mechanical subdivision process with a smooth computational alternative that supports gradient-based optimization.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11810250B2Systems and methods of hierarchical implicit representation in octree for 3D modeling
Publication Date: 2023.11.07 TENCENT AMERICA LLC
  • US11810250B2 patent drawing
  • US11810250B2 patent drawing
  • US11810250B2 patent drawing

AI summary

An electronic apparatus performs a method of representing a 3D shape that includes: dividing a 3D space enclosing the 3D shape into a plurality of 3D spaces with a hierarchical octree structure; generating local implicit functions, and each of the local implicit functions corresponds to a respective 3D space of the plurality of 3D spaces; and reconstructing a representation of the 3D shape from the local implicit functions with the hierarchical octree structure. In some embodiments, the 3D space is recursively subdivided into the child octants according to the surface occupancy and richness of the geometry of the 3D shape, and a respective local implicit function is generated corresponding to a geometry of a part of the surface.