Monocular UAV Door Detection via Edge and Vanishing Point Analysis

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Solution Overview

Problem

Current door detection systems for UAVs in corridor exploration are resource-intensive, rely on depth information, and are sensitive to door appearances, making them inefficient and unreliable for real-time navigation.

Innovation Solution

A computationally efficient door detection system using a single monocular camera that detects edge points, connects them to form long lines, determines vanishing points, and verifies door candidates through intensity profiles and template matching, allowing UAVs to navigate through corridors without requiring depth information or specific door appearances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If computationally intensive algorithms are used for door detection, then detection accuracy is improved, but computational load increases beyond UAV processing capabilities

Engineering Contradiction:
Improvedoor detection accuracyVSAvoidcomputational load
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The door detection process is segmented into distinct stages: edge detection, line formation, vanishing point calculation, and door verification. Each stage processes only relevant features, reducing overall computational load while maintaining detection accuracy through progressive refinement of candidate regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system extracts only essential features (edge points and line orientations) from the image data, discarding redundant information. By focusing solely on geometric properties rather than full image processing, the computational requirements are reduced to levels suitable for UAV onboard processors.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If depth information and multiple sensors are used for door detection, then detection reliability is improved, but device complexity increases

Engineering Contradiction:
Improvedoor detection reliabilityVSAvoidsensor system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The monocular camera performs multiple functions: edge detection, line orientation measurement, and vanishing point calculation. This single sensor replaces what would otherwise require multiple specialized sensors (depth cameras, laser range finders), reducing system complexity while maintaining detection reliability through multi-purpose utilization of available data.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system introduces vanishing point calculation as an intermediary step that bridges the gap between simple edge detection and reliable door identification. This mathematical construct serves as a mediator that provides geometric constraints without requiring direct depth measurement, enabling robust door detection using only 2D image data.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If appearance-based methods are used for door detection, then detection accuracy is improved for specific door types, but adaptability to varying door appearances deteriorates

Engineering Contradiction:
Improvedoor detection accuracyVSAvoiddoor appearance variability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system changes the detection parameters from appearance-based features (color, texture, material) to geometric parameters (edge orientation, line intersections, vanishing point position). This parameter transformation makes the detection method invariant to appearance variations while maintaining accuracy through consistent geometric properties of door structures across different door types.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9978149B1System and method for door detection for corridor exploration
Publication Date: 2018.05.22 HRL LAB
  • US9978149B1 patent drawing
  • US9978149B1 patent drawing
  • US9978149B1 patent drawing

AI summary

Described is a system for door detection for use with an unmanned aerial vehicle (UAV). The system receive a video input image from a single monocular camera. Edge points are detected in the video, with the edge points connected to form long edge lines. Orientations of the long edge lines are determined, such that long edge lines having a substantially vertical orientation are designated as initial door line candidates and long edge lines having a non-vertical, non-horizontal orientation are designated for use in detecting a vanishing point. A vanishing point is then detected in the video frame. Thereafter, intensity profile and line properties of the door line candidates are calculated. Finally, it is verified if the door line candidates are real world door lines and, if so, an area between the real world door lines is designated as an open door.