Distance Measurement Utilizing Image-Based Triangulation

Liebe, Carl Christian; Coste, Keith

doi:10.1109/jsen.2012.2212428

Cited by 17 publications

(6 citation statements)

References 31 publications

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“…Results show that, while the depth of structural defect (below 40 mm) has little effect on measurement accuracy, measuring distance is the critical factor influencing measurement accuracy. Measurement error increases quadratically as measurement distance and the maximum value is about 2.3 mm at the measurement distance of 4 m. This result outperforms current research work (Liebe & Coste, 2013;Mueller et al, 2015) but remains insufficient for the measurement of bulging since early bulging lies below 1 mm. Note that the actual measurement error can be larger if considering system calibration error.…”

Section: Evaluation Of Measurement Accuracymentioning

confidence: 52%

Assessment of out‐of‐plane structural defects using parallel laser line scanning system

Li,

Su,

Pan

2023

Computer aided Civil Eng

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A precise parallel laser line scanning system has been developed to assess the depth of out‐of‐plane structural defects on concrete surfaces. This system comprises a digital camera, dual line laser diodes, and positioning rigid arms that create a triangulation‐based setup. Laser lines are distorted when projected onto an out‐of‐plane defect. A new image processing algorithm has been devised to extract depth information from the distorted laser strips. Parallel laser lines are used to ensure that imaged laser strips do not intersect, thereby simplifying the depth assessment of defects at different distances and enabling the generation of defect profiles from a single image. The system has been validated through laboratory and field tests, demonstrating its effectiveness and accuracy. Compared to other noncontact measurement techniques, this system stands out due to its simplicity, cost‐effectiveness, efficiency, and superior accuracy for long‐range measurements, rendering it suitable for on‐site scanning of textureless uneven engineering objects.

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Section: Evaluation Of Measurement Accuracymentioning

confidence: 52%

Assessment of out‐of‐plane structural defects using parallel laser line scanning system

Li,

Su,

Pan

2023

Computer aided Civil Eng

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“…To do so, as can be seen in Figure 1 a, a laser beam is emitted towards a diffusely reflecting measurement surface. A part of the scattered light is then imaged by a lens onto a 2D detector array, usually a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) detector [ 14 ]. Hereby, the unknown distance d can be calculated according to

…”

Section: Fundamentalsmentioning

confidence: 99%

“…Most commercialized triangulation systems typically have a relative precision of around

at a working distance of 20–1000

with a measurement range of

[ 13 ], though there are a few systems available with a measurement range of up to several meters [ 2 ]. Liebe et al [ 14 ] recently introduced a laser triangulation system for a measurement range of 0.5–10

, achieving an accuracy of around

at a distance of 1

.…”

Section: Introductionmentioning

confidence: 99%

Optical Setup for Error Compensation in a Laser Triangulation System

Kienle

Batarilo

Akgül

et al. 2020

Sensors

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Absolute distance measurement is a field of research with a large variety of applications. Laser triangulation is a well-tested and developed technique using geometric relations to calculate the absolute distance to an object. The advantages of laser triangulation include its simple and cost-effective setup with yet a high achievable accuracy and resolution in short distances. A main problem of the technology is that even small changes of the optomechanical setup, e.g., due to thermal expansion, lead to significant measurement errors. Therefore, in this work, we introduce an optical setup containing only a beam splitter and a mirror, which splits the laser into a measurement beam and a reference beam. The reference beam can then be used to compensate for different error sources, such as laser beam dithering or shifts of the measurement setup due to the thermal expansion of the components. The effectiveness of this setup is proven by extensive simulations and measurements. The compensation setup improves the deviation in static measurements by up to 75%, whereas the measurement uncertainty at a distance of 1 m can be reduced to 85 μm. Consequently, this compensation setup can improve the accuracy of classical laser triangulation devices and make them more robust against changes in environmental conditions.

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“…We mapped sparse point cloud data into bird’s eye view (BEV) images as deep learning frameworks that can be effectively used for feature extraction and inference [ 10 ]. When the object was detected by the simplified YOLOv4 detector, we fit the bounding box onto the BEV map and determined the distance to the object using triangulation distance measurement [ 11 ]. Subsequently, we performed the Euler region proposal described by Simon et al [ 1 ] to project 3D bounding boxes onto the 2D image.…”

Section: Introductionmentioning

confidence: 99%

Accurate 3D to 2D Object Distance Estimation from the Mapped Point Cloud Data

Usmankhujaev

Baydadaev

Kwon

2023

Sensors

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Distance estimation is one of the oldest and most challenging tasks in computer vision using only a monocular camera. This can be challenging owing to the presence of occlusions, noise, and variations in the lighting, texture, and shape of objects. Additionally, the motion of the camera and objects in the scene can affect the accuracy of the distance estimation. Various techniques have been proposed to overcome these challenges, including stereo matching, structured light, depth from focus, depth from defocus, depth from motion, and time of flight. The addition of information from a high-resolution 3D view of the surroundings simplifies the distance calculation. This paper describes a novel distance estimation method that operates with converted point cloud data. The proposed method is a reliable map-based bird’s eye view (BEV) that calculates the distance to the detected objects. Using the help of the Euler-region proposal network (E-RPN) model, a LiDAR-to-image-based method for metric distance estimation with 3D bounding box projections onto the image was proposed. We demonstrate that despite the general difficulty of the BEV representation in understanding features related to the height coordinate, it is possible to extract all parameters characterizing the bounding boxes of the objects, including their height and elevation. Finally, we applied the triangulation method to calculate the accurate distance to the objects and statistically proved that our methodology is one of the best in terms of accuracy and robustness.

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Distance Measurement Utilizing Image-Based Triangulation

Cited by 17 publications

References 31 publications

Assessment of out‐of‐plane structural defects using parallel laser line scanning system

Assessment of out‐of‐plane structural defects using parallel laser line scanning system

Optical Setup for Error Compensation in a Laser Triangulation System

Accurate 3D to 2D Object Distance Estimation from the Mapped Point Cloud Data

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