3D Object Detection via 2D Bounding Box Reconstruction

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Solution Overview

Problem

Current 3D object detection techniques face challenges in accuracy, dependency on specific data sources, and high resource consumption, making them impractical for many applications, especially on low-power devices.

Innovation Solution

The approach involves detecting objects in 2D as bounding boxes in calibrated 2D images, matching corresponding boxes to reconstruct objects in 3D, and refining 3D bounding boxes using sparse 3D points from SfM photogrammetry to improve accuracy and reduce resource utilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If 3D object detection is performed using traditional methods (3D model reconstruction, SfM photogrammetry), then detection capability is achieved, but accuracy is poor and resource consumption is high

Engineering Contradiction:
Improvedetection accuracyVSAvoidresource consumption
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent inverts the traditional 3D detection approach by performing 2D object detection on multiple calibrated images and then reconstructing 3D bounding boxes from the matched 2D detections. This dimensionality inversion leverages the maturity of 2D detection algorithms while avoiding the complexity of direct 3D detection, thereby improving accuracy while reducing resource consumption.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Instead of reconstructing 3D models first and then detecting objects (traditional approach), the patent detects objects in 2D space first and then reconstructs their 3D positions. This inversion of the detection pipeline allows using well-established 2D detection techniques and avoids the computational burden of 3D model reconstruction, resolving the contradiction between accuracy and resource consumption.

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If 3D model reconstruction is performed using SfM photogrammetry, then 3D data is obtained, but the process is complex and may fail for difficult-to-reconstruct objects

Engineering Contradiction:
Improvedetection reliabilityVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs object detection in 2D space where mature algorithms exist, then reconstructs 3D information from the 2D results. This approach bypasses the need for complex 3D model reconstruction while achieving reliable detection, as 2D detection is more robust and less prone to failure on difficult objects.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent extracts only the necessary 3D bounding box information from 2D detections rather than performing full 3D model reconstruction. This selective extraction of minimal required data (3D position, size, orientation) avoids the complexity of complete scene reconstruction while maintaining detection reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If sparse 3D points from SfM are used to refine 3D bounding boxes, then accuracy is improved, but resource consumption increases

Engineering Contradiction:
Improve3D bounding box accuracyVSAvoidcomputing resource usage
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent uses sparse 3D points from SfM photogrammetry selectively to refine 3D bounding boxes only when available and beneficial, rather than performing complete 3D reconstruction. This partial use of 3D point data improves accuracy for objects where refinement is possible while avoiding the excessive resource consumption of full 3D scene reconstruction.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS11281935B23D object detection from calibrated 2D images
Publication Date: 2022.03.22 BENTLEY SYSTEMS INC
  • US11281935B2 patent drawing
  • US11281935B2 patent drawing
  • US11281935B2 patent drawing

AI summary

In an example embodiment, techniques are provided for 3D object detection by detecting objects in 2D (as 2D bounding boxes) in a set of calibrated 2D images of a scene, matching the 2D bounding boxes that correspond to the same object and reconstructing objects in 3D (represented as 3D bounding boxes) from the corresponding, matched 2D bounding boxes. The techniques may leverage the advances in 2D object detection to address the unresolved issue of 3D object detection. If sparse 3D points for the scene are available (e.g., as a byproduct of SfM photogrammetry reconstruction) they may be used to refine the 3D bounding boxes (e.g., to reduce their size).