Structured Light Research Papers - Academia.edu (original) (raw)

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- Remote Sensing, Production, Structure, Time Series

2. Abstract Automatic 3D acquisition devices (often called 3D scanners) allow to build highly accurate models of real 3D objects in a cost-and time-effective manner. We have experimented this technology in a particular application context: the acquisition of Cultural Heritage artefacts. Specific needs of this domain are: medium-high accuracy, easy of use, affordable cost of the scanning device, self-registered acquisition of shape and color data, and finally operational safety for both the operator and the scanned artefacts. According to ...

- by Paolo Pingi
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- Computer Science, Cultural Heritage, Reconstruction, Radiosity
- by Ashutosh Natraj
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- Sensors, Estimation, Structured Light, Real Time

Imaging technologies are transforming the study and presentation of artefacts. The contributors to this volume are at the vanguard of applying developing technologies to cultural heritage, and their chapters discuss ways in which various techniques are being used for research, digital cataloguing, and public engagement. Eight chapters highlight diverse methods in imaging and presentation (e.g. photogrammetry, multispectral and hyperspectral imaging, structure-from-light, digital microscopy, 3D printing, and virtual and augmented reality) applied to objects of differing forms, size, media and cultural origin, including standing stones in pre-Columbian Nicaragua, Egyptian and Roman sculpture, Mesopotamian cylinder seals, and rock crystal vessels made in the early medieval Islamic world. Aimed at contributing to knowledge-transfer between sciences, humanities, and cultural heritage professionals, this volume offers updated, accessible accounts of digital imaging of objects for general and specialist audiences.

- by Rachel Wood
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- Archaeology, Art History, Photogrammetry, Fluorescence Spectroscopy
- by E. Mouaddib
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- Computer Vision, Pattern Recognition, Depth Perception, Structured Light
- by Eduardo Zalama and +1
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- Engineering, Computer Vision, Automotive Industry, Quality Control
- by David Burton
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- Computer Vision, Qualitative evaluation, Wavelet Transform, Structured Light

Résumé Cet article présente une méthode de segmentation d'images issues d'un capteur de vision en lumière structurée, allant du seuillage local auto-adaptatif au décodage du motif. Ce dernier est basé sur un algorithme de coalescence initialisé grâce à la topologie de l'espace des couleurs utilisé, le CIE-Lab, proche de la perception humaine.

- by El Mustapha Mouaddib
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- Structured Light, Human Perception, Adaptive Thresholding
- by Ursula Gonzales-barron and +1
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- Food Engineering, Structured Light, Food Sciences, Fermentation Process

Realizzazione di un modello di scansione 3D a luce strutturata.

- by Marco Tofoni
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- 3D Laser scanning (Architecture), Structured Light

In recent years, various methodologies of shape reconstruction have been proposed with the aim at creating Computer-Aided Design models by digitising physical objects using optical sensors. Generally, the acquisition of 3D geometrical data includes crucial tasks, such as planning scanning strategies and aligning different point clouds by multiple view approaches, which differ for user’s interaction and hardware cost. This paper describes a methodology to automatically measure three-dimensional coordinates of fiducial markers to be used as references to align point clouds obtained by an active stereo vision system based on structured light projection. Intensity-based algorithms and stereo vision principles are combined to detect passive fiducial markers localised in a scene. 3D markers are uniquely recognised on the basis of geometrical similarities. The correlation between fiducial markers and point clouds allows the digital creation of complete object surfaces. The technology has been validated by experimental tests based on nominal benchmarks and reconstructions of target objects with complex shapes.

En la actualidad, existen herramientas computacionales para realizar reconocimiento de objetos mediante el análisis de imágenes bidimensionales, técnicas abordadas por una línea de estudio denominada Visión por Computadora. Por otro lado, sabemos de los procesos de reconstrucción tridimensional, que existe información en las líneas de luz láser proyectadas sobre superficies de objetos. Este trabajo propone un método de análisis de la deformación de esas líneas de luz láser, para realizar reconocimiento de objetos, sin necesidad de una reconstrucción tridimensional. El proceso de reconocimiento se realizó mediante el uso de clasificadores supervisados, tales como K-Nearest Neighbor y Naïve Bayes, así como el uso de una red neuronal artificial con su entrenamiento por backpropagation. Para todos los algoritmos implementados se llegó a un porcentaje de reconocimiento superior al 89%.

- by Jordi Pagès
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- Computer Vision, Pattern Recognition, Structured Light, Point of View

Every year, maritime archaeologists around the globe are faced with the daunting task of recording hundreds, if not thousands, of individual ship timbers. The in-depth recording of ship timbers is a process which is both challenging and laborious, but it is an indispensable step in order to fully understand the construction of the ship the timbers formed a part of, and as archaeologists it is our duty to document all the information these complex artefacts hold to the best of our abilities. In this article, the authors first provide an overview of the methods currently in use for ship timber recording, namely 2D scaled drawing, 2D tracing, 3D contact digitising and 3D scanning. The respective advantages and limitations of these methods are then discussed in light of the various scientific and practical considerations that go into choosing a recording method for a project. Next, a new approach to ship timber recording, termed the “3D annotated scans method”, is introduced and discussed using a recent case study in northern Germany. At its core the method consists of two phases; a 3D scanning phase in which the timber is scanned in 3D, followed by a 3D annotation phase in which the recorder interprets the timber by tracing diagnostic features such as fasteners and toolmarks directly onto the timber’s digital model. The authors conclude that this new approach represents an improvement over current methods—both in terms of the quality of the scientific outputs and in terms of recording efficiency—and that, besides being implemented for the recording of ship timbers, the same method can also be used for a wide range of other heritage applications.

- by Thomas Van Damme and +3
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- Archaeology, Maritime Archaeology, Photogrammetry, Cultural Heritage

- by Massimiliano Ditta and +1
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- Archaeology, Maritime Archaeology, Photogrammetry, Cultural Heritage

The following contribution focuses on the low-cost Shining 3D EinScan-Pro scanner, above all the analysis of its precision and accuracy. The need to prove the functioning of this instrumentation in practical cases (the sculptures by Eduardo Chillida preserved in the Chillida-Leku Museum and along with some artefacts collected in the Archaeological Museum of Sarno), has led to the comparison and validation of the instrument through a methodology necessarily diversified from the guideline VDI/VDE 2634, part 2 and part 3, characteristics to the test the optical 3D measuring systems with planar measurement, which works according to the triangulation principle. In particular, two types of comparisons were made: geometric-formal and metric-dimensional. The first type of analysis was carried out analysing the geometric parameters of the models, suitable for validating the information: dimensional (difference between some main measurements); superficial (total mesh extension) and of the form (that is, the discrepancies returned through a DEM analysis). The second type of analysis, instead, of the metric type, was carried out. The complete results of the various analyses will be presented and critically discussed within this contribution in order to prove the stability and the metric quality of this hand-held EinScan-Pro, following the comparison with medium-high end systems now well established in the field of cultural heritage survey.

- by Sara Morena and +1
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- Cultural Heritage, Low Cost Technology, Sculpture, Museums

This is an introduction to the special issue of the DAACH journal dedicated to 3D scanning and its applications in Archaeology

- by Stuart Bradley
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- Mechanical Engineering, Architecture, Beamforming, Classical Physics
- by G. Vougioukalakis and +1
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- Technology Education, Chemical and Biological Engineering, Seasonality, Structured Light
- by Magdalena Kupiec
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- Mechanical Engineering, Applied Mathematics, Numerical Analysis, Measurement

- by Jens Auer
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- Archaeology, Maritime Archaeology, Photogrammetry, Cultural Heritage
- by Holly Rushmeier
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- Cultural Heritage, Mesh generation, Virtual Reality, 3-D Imaging
- by ALFREDO GARDEL-VICENTE
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- Artificial Vision, Structured Light, Mobile Robot, Infrared
- by Matt Cutts and +1
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- Image-based Rendering, Augmented Reality, Virtual Environment, Structured Light

In this paper we present a theoretical method, together with its experimental confirmation, to obtain structures of light by connecting diffraction-resistant cylindrical beams of finite lengths and different radii. The resulting ``Lego-beams'' can assume, on demand, various
interesting spatial configurations. We experimentally generate
some of them by using a computational holographic technique and a
Spatial Light Modulator. Our results can find applications in all
fields where structured light beams are needed, such as optical
tweezers, optical guiding of atoms, light orbital angular momentum
control and others. [OCIS codes: (999.9999) Non-diffracting waves; (260.1960) Diffraction theory; (070.7545) Wave propagation; (050.1120)
Apertures; (050.1755) Computational electromagnetic methods].

- by Erasmo Recami
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- Structured Light, Localized Waves, "Frozen Waves", Non-Diffracting Waves
- by Rosaria Musumeci
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- Civil Engineering, Geology, Computer Vision, Coastal Engineering

We propose Micro-baseline Structured Light (MSL), a novel 3D imaging approach designed for small form-factor devices such as cell-phones and miniature robots. MSL operates with small projector-camera baseline and low-cost projection hardware, and can recover scene depths with computationally lightweight algorithms. The main observation is that a small baseline leads to small disparities, enabling a first-order approximation of the non-linear SL image formation model. This leads to the key theoretical result of the paper: the MSL equation, a linearized version of SL image formation. MSL equation is under-constrained due to
two unknowns (depth and albedo) at each pixel, but can be efficiently solved using a local least squares approach. We analyze the performance of MSL in terms of various system parameters such as projected pattern and baseline, and provide guidelines for optimizing performance. Armed with these insights, we build a prototype to experimentally examine the theory and its practicality.

- by Jian Wang
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- Structured Light
- by Elizabeth Croft
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- Cognitive Science, Computer Vision, Machine Vision, Distributed System

Research interest in rapid structured-light imaging has grown increasingly for the modeling of moving objects, and a number of methods have been suggested for the range capture in a single video frame. The imaging area of a 3D object using a single projector is restricted since the structured light is projected only onto a limited area of the object surface. Employing additional projectors to broaden the imaging area is a challenging problem since simultaneous projection of multiple patterns results in their superposition in the light-intersected areas and the recognition of original patterns is by no means trivial. This paper presents a novel method of multi-projector color structured-light vision based on projector–camera triangulation. By analyzing the behavior of superposed-light colors in a chromaticity domain, we show that the original light colors cannot be properly extracted by the conventional direct estimation. We disambiguate multiple projectors by multiplexing the orientations of projector patterns so that the superposed patterns can be separated by explicit derivative computations. Experimental studies are carried out to demonstrate the validity of the presented method. The proposed method increases the efficiency of range acquisition compared to conventional active stereo using multiple projectors.

- by Changsoo Je
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- Computer Vision, Structured Light, Range Imaging, Color Stripe

Three-dimensional (3D) image acquisition systems are rapidly becoming more affordable, especially systems based on commodity electronic cameras. At the same time, personal computers with graphics hardware capable of displaying complex 3D models are also becoming inexpensive enough to be available to a large population. As a result, there is potentially an opportunity to consider new virtual reality applications as diverse as cultural heritage and retail sales that will allow people to view realistic 3D objects on home computers.Although there are many physical techniques for acquiring 3D data—including laser scanners, structured light and time-of-flight—there is a basic pipeline of operations for taking the acquired data and producing a usable numerical model. We look at the fundamental problems of range image registration, line-of-sight errors, mesh integration, surface detail and color, and texture mapping. In the area of registration we consider both the problems of finding an initial global alignment using manual and automatic means, and refining this alignment with variations of the Iterative Closest Point methods. To account for scanner line-of-sight errors we compare several averaging approaches. In the area of mesh integration, that is finding a single mesh joining the data from all scans, we compare various methods for computing interpolating and approximating surfaces. We then look at various ways in which surface properties such as color (more properly, spectral reflectance) can be extracted from acquired imagery. Finally, we examine techniques for producing a final model representation that can be efficiently rendered using graphics hardware.

- by Fi Terra
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- Cultural Heritage, Mesh generation, Virtual Reality, 3-D Imaging

For structured-light range imaging, colour stripes can be used for increasing the number of distinguishable light patterns compared to binary black-and-white stripes. Therefore, an appropriate use of colour patterns can reduce the number of required light projections for imaging an object scene, and range imaging can be achievable in a single video frame or in “one-shot”. On the other hand, the reliability and range resolution attainable from colour stripes are generally lower than those from temporally encoded binary black-and-white patterns since colour contrast is affected by object colour reflectance and ambient light. This paper presents new methods for selecting stripe colours and designing multiple-stripe patterns for “one-shot” and “two-shot” imaging. We show that maximizing colour contrast between the stripes in one-shot imaging reduces the ambiguities resulting from coloured object surfaces and limitations in sensor/projector resolution. Moreover, a cross-stripe gradient method is presented to improve estimation of illumination patterns in one-shot imaging. Two-shot imaging adds an extra video frame and maximizes the colour contrast between the first and second video frames to diminish the ambiguities even further. Experimental results and discussion demonstrate the effectiveness and robustness of the presented one-shot and two-shot colour-stripe imaging schemes.

- by Changsoo Je
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- Computer Vision, Structured Light, Range Imaging, Color Stripe
- by Clarence Wust
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- Cognitive Science, Structured Light, Color Image, Phase Shift
- by Khosrow Ghavami
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- Civil Engineering, Steel Structure, Case Study, Structured Light
- by Keith White
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- Algorithms, Magnetic Resonance Imaging, Software, Fourier Analysis

This paper describes a new phase extraction algorithm for 3D optical profilometry based on the projection of a periodic light pattern and phase measurement (phase profilometry). The algorithm uses a square wave to demodulate phase and moving averages and comb-shaped filters to extract the phase information from low frequency. The proposed algorithm is compared with the two major profilometry techniques, namely Fourier domain profilometry and signal domain profilometry based on FIR low-pass filtering. Comparison is focused on adaptiveness to changes of the pattern frequency, ability to deal with nonuniform surfaces and computational complexity. Adaptiveness analysis is carried out by means of simulations. The issue of nonuniform surfaces is discussed on the basis of experimental results obtained from application of phase profilometry to on-line 3D printed circuit board inspection. With regard to complexity, theoretical estimates are verified by means of actual computation time measurements.

- by Frank Boland
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- Cognitive Science, Structured Light
- by Fabio Bruno
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- 3-D Imaging, Coral Reef, Structured Light, Stereo Vision
- by Emre Sancak
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- Civil Engineering, Concrete Technology, Weight Loss, Compressive Strength

We have constructed a thermal stereoscope utilizing three digital SLR cameras and an infrared camera for rapid surface reconstruction of diabetic foot geometry and temperature distribution. A structured light pattern is projected on to the foot to provide approximately 2500 reconstructed points. The reconstructed point cloud is then fitted to a finite element model, producing root mean squared errors of less than 0.4 mm.

- by Poul Nielsen
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- Finite element method, Thermography, Humans, Image Reconstruction

ABSTRACT A new method for robust noncontact diameter determination of spherical objects is studied. Applications can be found in the grinding and in the robotic inspection fields. The principle is based on laser triangulation under structured lighting, where laser planes create lines on the object under test, which are observed by a charge-coupled device camera. Two methods are proposed for radius calculation. The first one is an extension of what we call the "three-tangent method," which is developed in the context of a previous study consisting of the measurement of the diameter of cylinders. The second one is the gradient-descent method, which is a statistical optimization technique. Experimental results obtained on a preprototype setup with both methods are given and compared, showing slightly better performances for the "three-tangent method." A general accuracy of about 1% for spherical objects of 10-30 cm in diameter is claimed for distances ( a priori not known) up to 2.5 m

- by Christian Eugène
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- Image Processing, Machine Vision, Structured Light, OPTIMIZATION TECHNIQUE

Nowadays, the high speed (e.g., kilo-Hertz) refreshing rate of the digital micro-mirror device (DMD) has
enabled superfast 3D shape measurement using the binary defocusing technique. This research finds that
when the system reaches its extreme binary pattern refreshing rate, the transient response of the DMD
induces a coupling effect (i.e., two neighboring patterns blend together) that may cause substantial
measurement error. Since this transient response repeats itself, this systematic measurement error is
substantially reduced to a negligible level when the timing between the projector and the camera is
properly adjusted. Experimental results are presented to demonstrate the observed phenomena, and the
success of utilizing the proposed method to overcome the problems associated with the transient
response of the DMD.

- by Bhaskar Bhattacharya
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- Optics, Structured Light, Mechanical Properties of DMD