Terrestrial Laser Scanner Moving Object Detection

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Solution Overview

Problem

Terrestrial laser scanning systems face challenges in efficiently excluding unwanted moving objects from measurement data, leading to inconsistencies and disturbances in 3D point cloud generation, which are often detected too late for correction.

Innovation Solution

An automatic method using a camera system integrated with the laser scanner to detect and classify moving objects through image processing, including neural networks, allowing for real-time reaction and exclusion of unwanted objects from the scanning process, ensuring accurate data collection and consistency between intensity and digital images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If terrestrial laser scanning is performed continuously over surfaces to generate 3D point cloud data, then measurement completeness and coverage are improved, but moving objects may enter the measurement space during scanning causing data inconsistencies and disturbances

Engineering Contradiction:
Improve3D point cloud data accuracyVSAvoidmeasurement consistency
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The system performs preliminary detection of moving objects using image processing before the laser scanning begins. The camera captures images of the measurement space and the evaluation unit identifies moving objects in advance, allowing the system to prepare appropriate reactions (such as pausing scanning or adjusting measurement parameters) before the moving object can disturb the measurement process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the measurement space during scanning using the camera and evaluation unit. When a moving object is detected, the system provides feedback by triggering reactions that adjust the scanning process in real-time, such as pausing the laser scanner or modifying measurement parameters, thereby maintaining data consistency and preventing disturbances.

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If the scanning process is paused to avoid moving objects, then data consistency is improved, but measurement time increases

Engineering Contradiction:
Improvedata consistencyVSAvoidmeasurement duration
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

By detecting moving objects in advance using image processing before they enter the critical measurement path, the system can plan and execute minimal interruptions. The preliminary detection allows for proactive scheduling of scanning pauses only when necessary, rather than reactive pausing, thereby reducing overall measurement time while maintaining data consistency.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the scanning process based on real-time detection of moving objects. Instead of fixed pausing schedules, the laser scanning is paused or adjusted only when and where moving objects are detected, allowing the majority of the measurement space to be scanned continuously. This dynamic adaptation optimizes the balance between data consistency and measurement efficiency.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If multiple sequential images are acquired and processed to detect moving objects, then detection accuracy is improved, but processing time and computational load increase

Engineering Contradiction:
Improvemoving object detection accuracyVSAvoidimage processing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system processes multiple sequential images to detect moving objects with high accuracy, but only to the extent necessary for reliable detection. The evaluation unit analyzes image sequences and stops processing once sufficient information is obtained to confidently identify or rule out moving objects, avoiding unnecessary computational overhead while maintaining detection precision.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The image processing system is integrated directly into the scanning device, allowing the measurement system to serve itself by performing detection and analysis internally. This self-service capability reduces external processing delays and enables real-time feedback without adding significant overhead to the overall measurement process.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables real-time detection and exclusion of moving objects, preventing data disturbances and ensuring accurate, consistent 3D point cloud generation, allowing for immediate correction and improved data quality during scanning.

Implementation Method 1

at least one radiation source for generating optical measuring radiation, often laser radiation

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

The distance measuring device can be embodied for example according to the principles of time of flight (TOF), phase, waveform digitizer (WFD) or interferometric measurement

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 3

interferometric measurement

Methodology Applied
Scientific EffectInterferometry: Interference

Implementation Method 4

The deflecting unit can be realized in the form of a moving mirror or alternatively also by other elements suitable for controlled angular deflection of optical radiation, such as, for example, rotatable prisms

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4270050A1Method for coordinative measuring by terrestrial scanning with image-based interference detection of moving objects
Publication Date: 2023.11.01 LEICA GEOSYSTEMS AG
  • EP4270050A1 patent drawingFigure 1
  • EP4270050A1 patent drawingFigure 2a~2c
  • EP4270050A1 patent drawingFigure 2d~3

AI summary

Automatic method for coordinative measuring of a measurement space with a stationary terrestrial scanning measuring device (1) having an emitting unit for directed emission of radiation as a free beam (3) and at least one camera (2) arranged in known spatial relationship to the emitting unit.