Stereoscopic Imaging Technique Research Articles

Image-Based Hidden Damage Detection Method: Combining Stereo Digital Image Correlation and Finite Element Model Updating.

Maintenance and damage detection of structures are crucial for ensuring their safe usage and longevity. However, damage hidden beneath the surface can easily go unnoticed during inspection and assessment processes. This study proposes a detection method based on image techniques to detect and assess internal structural damage, breaking the limitation of traditional image methods that only analyze the structure's surface. The proposed method combines full-field response on the structure's surface with finite element model updating to reconstruct the structural model, using the reconstructed model to detect and assess hidden structural damage. Initially, numerical experiments are conducted to generate known damaged areas and parameter distributions. Data from these experiments are used to update the finite element model, establish and validate the proposed model updating method, and assess its accuracy in evaluating hidden damage, achieving an accuracy rate of 90%. Furthermore, discussions on more complex damage scenarios are carried out through numerical experiments to demonstrate the feasibility and applicability of the proposed method in reconstructing different forms of damage. Ultimately, this study utilizes stereoscopic digital imaging techniques to acquire full-field information on surfaces, and applies the proposed method to reconstruct the structure, enabling the detection and assessment of hidden damage with an accuracy rate of 86%.

Fungal and bacterial species richness in biodeteriorated seventeenth century Venetian manuscripts

Historical paper documents are susceptible to complex degradation processes, including biodeterioration, which can progressively compromise their aesthetic and structural integrity. This study analyses seventeenth century handwritten historical letters stored at the Correr Museum Library in Venice, Italy, exhibiting pronounced signs of biodeterioration. The techniques used encompassed traditional colony isolation on agar plates and proteomics analyses, employing nanoscale liquid chromatography coupled with high-resolution mass spectrometry (nano-LC–MS). Fluorescence microscopy was used for the first time in the historical paper biodeterioration context to supplement the conventional stereoscopic, optical, and scanning electron microscopic imaging techniques. This method enables the visualisation of microorganisms beyond and beneath the paper’s surface through their natural intrinsic autofluorescence in a non-invasive and non-destructive way. The results demonstrate a diverse, complex, and abundant microbiota composed of coexisting fungal and bacterial species (Ascomycota, Mucoromycota, Basidiomycota, Proteobacteria, and Actinobacteria), along with mite carcasses, insects, parasites, and possibly protists. Furthermore, this study reveals certain species that were not previously documented in the biodeterioration of historical paper, including human pathogens, such as Histoplasma capsulatum, Brucella, Candida albicans, and species of Aspergillus (A. flavus, A. fumigatus, A. oryzae, A. terreus, A. niger) known to cause infections or produce mycotoxins, posing substantial risk to both artefacts and humans.

Hybrid full-pose parameter calibration of a freeform illuminator for Fourier ptychographic microscopy.

As a typical computational method, Fourier ptychographic microscopy (FPM) can realize high spatial resolution and quantitative phase imaging while preserving the large field of view with a low numerical aperture (NA) objective. A programmable light-emitting diode (LED) array is used as a typical illuminator in an FPM system, and the illumination parameters of each LED element are crucial to the success of the FPM reconstruction algorithm. Compared with LED arrays arranged in rectangular arrays, LED arrays with special structures such as domes or rings can effectively improve FPM imaging results and imaging efficiency. As a trade-off, their calibration difficulty is greatly increased due to the lack of geometric constraints of rectangular arrays. In this paper, we propose an effective hybrid full-pose parameter calibration method for freeform LED array illuminators, combining stereoscopic 3D imaging techniques and the geometric constraints of the microscopic platform. First, a stereovision system is used to obtain the accurate 3D position of each LED element of the freeform illuminator and to construct a rigid 3D coordinate LED array system. Then, calibration between the coordinate system of the LED array and that of the optical imaging component is realized according to the geometric features of the brightfield-to-darkfield edges. Finally, we verify the feasibility and effectiveness of the proposed method through full-pose parameter calibration of LED arrays with different arrangement rules.

Predicting dynamic fragmentation characteristics from high-impact energy events utilizing terrestrial static arena test data and machine learning

To continue space operations with the increasing space debris, accurate characterization of fragment fly-out properties from hypervelocity impacts is essential. However, with limited realistic experimentation and the need for data, available static arena test data, collected utilizing a novel stereoscopic imaging technique, is the primary dataset for this paper. This research leverages machine learning methodologies to predict fragmentation characteristics using combined data from this imaging technique and simulations, produced considering dynamic impact conditions. Gaussian mixture models (GMMs), fit via expectation maximization (EM), are used to model fragment track intersections on a defined surface of intersection. After modeling the fragment distributions, k-nearest neighbor (K-NN) regressors are used to predict the desired characteristics. Using Monte Carlo simulations, the K-NN regression is shown to predict the distributions for both the total number of fragments intersecting a given surface, as well as the expected total fragment velocity and mass associated with that surface. This information can then be used to estimate the kinetic energy of the particle to classify the particle and avoid debris collisions.

Parotidectomy and parapharyngeal space dissection: 3D anatomy

Parotidectomy and surgical access to the parapharyngeal space are common procedures for the head and neck surgeon, and an understanding of the complex anatomic relationships in this region is critical for safe navigation and management of both benign and malignant processes here. With the use of 3-dimension stereoscopic imaging techniques, parotidectomy and parapharyngeal space dissection are herein reviewed with an emphasis on important anatomic structures and their relationships. Parotidectomy and surgical access to the parapharyngeal space are common procedures for the head and neck surgeon, and an understanding of the complex anatomic relationships in this region is critical for safe navigation and management of both benign and malignant processes here. With the use of 3-dimension stereoscopic imaging techniques, parotidectomy and parapharyngeal space dissection are herein reviewed with an emphasis on important anatomic structures and their relationships.

Lateral neck dissection: 3D anatomy

Neck dissection is a commonly performed procedure in the treatment of most head and neck cancers, and principles of neck dissection surgery are used in the surgical treatment of a variety of benign processes as well. Developing a working knowledge of neck anatomy is critical for otolaryngologists in training to navigate through the neck competently and efficiently, whether during neck dissection or other transcervical surgical approaches. With the use of 3-dimensional stereoscopic imaging techniques, neck dissection is herein reviewed with an emphasis on understanding the anatomic relationships of the critical structures within the neck. Neck dissection is a commonly performed procedure in the treatment of most head and neck cancers, and principles of neck dissection surgery are used in the surgical treatment of a variety of benign processes as well. Developing a working knowledge of neck anatomy is critical for otolaryngologists in training to navigate through the neck competently and efficiently, whether during neck dissection or other transcervical surgical approaches. With the use of 3-dimensional stereoscopic imaging techniques, neck dissection is herein reviewed with an emphasis on understanding the anatomic relationships of the critical structures within the neck.

Total laryngectomy: 3D anatomy

Despite the advent of non-surgical treatment options for laryngeal cancer, as well as partial laryngeal surgery for larynx cancer, total laryngectomy remains an important tool in the treatment of larynx cancer and non-functional larynx. With the use of 3-dimensional stereoscopic imaging techniques, total laryngectomy is herein reviewed with an emphasis on understanding the anatomic relationships encountered and considered during this procedure. Despite the advent of non-surgical treatment options for laryngeal cancer, as well as partial laryngeal surgery for larynx cancer, total laryngectomy remains an important tool in the treatment of larynx cancer and non-functional larynx. With the use of 3-dimensional stereoscopic imaging techniques, total laryngectomy is herein reviewed with an emphasis on understanding the anatomic relationships encountered and considered during this procedure.

Compact Midwave Imaging System: Results from an Airborne Demonstration

The Compact Midwave Imaging System (CMIS) is a wide field of view, multi-angle, multi-spectral pushframe imager that relies on the forward motion of the satellite to create a two-dimensional (2D) image swath. An airborne demonstration of CMIS was successfully completed in January–February 2021 on the NASA Langley Research Center Gulfstream III. The primary objective of the four-flight campaign was to demonstrate the capability of this unique instrument to perform stereo observations of clouds and other particulates (e.g., smoke) in the atmosphere. It is shown that the midwave infrared (MWIR) spectral bands of CMIS provide a unique 24/7 capability with high resolution for accurate stereo sensing. The instrument relies on new focal plane array (FPA) technology, which provides excellent sensitivity at much warmer detector temperatures than traditional technologies. This capability enabled a compact, low-cost design that can provide atmospheric motion vectors and cloud heights to support requirements for atmospheric winds in the 2017–2027 Earth Science Decadal Survey. Applications include day/night observations of the planetary boundary layer, severe weather, and wildfires. A comparison with current space-based earth science instruments demonstrates that the SWIR/MWIR multi-spectral capability of CMIS is competitive with larger, more expensive instrumentation. Imagery obtained over a controlled burn and operating nuclear power plant demonstrated the sensitivity of the instrument to temperature variations. The system relies on a mature stereoscopic imaging technique applied to the same scene from two independent platforms to unambiguously retrieve atmospheric motion vectors (AMVs) with accurate height assignment. This capability has been successfully applied to geostationary and low-earth orbit satellites to achieve excellent accuracy. When applied to a ground-point validation case, the accuracy for the CMIS aircraft observations was 20 m and 0.3 m/s for cloud heights and motion vectors, respectively. This result was confirmed by a detailed error analysis with analytical and covariance models. The results for CMIS cases with underflights of Aeolus, CALIPSO, and Aqua provided a good validation of expected accuracies. The paper also showed the feasibility of accommodating CMIS on CubeSats to enable multiple instruments to be flown in a leader–follower mode.

Internal structure of intense collisional bedload transport

AbstractIntense bed load refers to a regime which is responsible of most of sediment transport in torrents and rivers during floods. Even if restricted to uniform steady conditions and well sorted particles, the liquid and solid phases interact in a rather complex way over the plane mobile bed. We focus on flow conditions where the sediment grains in the flow are supported by mutual contacts, primarily collisions, and not by the fluid turbulence. Nonetheless, the turbulent liquid stresses are important everywhere, but the top of the bed, and may not be neglected. Being particles and fluid reciprocally affecting at various scale, mechanical interpretations are challenging and not consolidated, yet. In this picture, it is clear that experimental evidences provide a fundamental, still lacking, piece of information.We contribute with new experiments in a tilting flume to face this need. Compared to previous laboratory tests, we apply various measuring techniques, getting to a robust validation of the acquired dataset. We exploited stereoscopic imaging techniques to capture the solid concentration and the three components of grain velocity, and extract the velocity fluctuations from the local mean values. Measured velocity distributions are independently checked by using an Ultrasonic Doppler Velocimetry technique.With all the needed quantities available, we exploited the constitutive relations based on the kinetic theory for granular flow, to highlight how the comparison between predictions and measurements works, deploying some accuracy deficiencies in the measurement and/or interpretation limits. Our results also address the attention to interfaces that separate layers affected by different rheological mechanisms. Along with pure experimental and theoretical aspects, we grasp the chance to use the data to check how the relations involving global quantities (discharges, friction factor, bed slope, flow depth), so common in hydraulic practice, work when the sediment transport is intense. © 2019 John Wiley & Sons, Ltd.

Development of an Image Processing Module for Autonomous Underwater Vehicles through Integration of Visual Recognition with Stereoscopic Image Reconstruction

This study investigated the development of visual recognition and stereoscopic imaging technology, applying them to the construction of an image processing system for autonomous underwater vehicles (AUVs). For the proposed visual recognition technology, a Hough transform was combined with an optical flow algorithm to detect the linear features and movement speeds of dynamic images; the proposed stereoscopic imaging technique employed a Harris corner detector to estimate the distance of the target. A physical AUV was constructed with a wide-angle lens camera and a binocular vision device mounted on the bow to provide image input. Subsequently, a simulation environment was established in Simscape Multibody and used to control the post-driver system of the stern, which contained horizontal and vertical rudder planes as well as the propeller. In static testing at National Cheng Kung University, physical targets were placed in a stability water tank; the study compared the analysis results obtained from various brightness and turbidity conditions in out-of-water and underwater environments. Finally, the dynamic testing results were combined with a fuzzy controller to output the real-time responses of the vehicle regarding the angles, rates of the rudder planes, and the propeller revolution speeds at various distances.

In situ vocal fold properties and pitch prediction by dynamic actuation of the songbird syrinx

The biomechanics of sound production forms an integral part of the neuromechanical control loop of avian vocal motor control. However, we critically lack quantification of basic biomechanical parameters describing the vocal organ, the syrinx, such as material properties of syringeal elements, forces and torques exerted on, and motion of the syringeal skeleton during song. Here, we present a novel marker-based 3D stereoscopic imaging technique to reconstruct 3D motion of servo-controlled actuation of syringeal muscle insertions sites in vitro and focus on two muscles controlling sound pitch. We furthermore combine kinematic analysis with force measurements to quantify elastic properties of sound producing medial labia (ML). The elastic modulus of the zebra finch ML is 18 kPa at 5% strain, which is comparable to elastic moduli of mammalian vocal folds. Additionally ML lengthening due to musculus syringealis ventralis (VS) shortening is intrinsically constraint at maximally 12% strain. Using these values we predict sound pitch to range from 350–800 Hz by VS modulation, corresponding well to previous observations. The presented methodology allows for quantification of syringeal skeleton motion and forces, acoustic effects of muscle recruitment, and calibration of computational birdsong models, enabling experimental access to the entire neuromechanical control loop of vocal motor control.

Stereoscopic Fotoğrafın Üretim Süreci ve Günümüzdeki Uygulamasına Bir Örnek: “Ayağıma Gelen Tarih” Projesi

As people's eyesight improved in time so as to perceive and evaluate the vibrations of light, they started to see and make sense of their environments much better. Human beings exploring themselves, nature and the characteristics of every living creature started to paint everything they were fascinated by and saw. As time passed by, people improved their skills about depicting the things around them, and tried to make the things in their paintings look more realistic/just like the way they saw them. For this purpose, they made several attempts and conducted experimental studies using different techniques. In the meantime, various techniques were developed; however, the oldest technique which is still used today is the use of anaglyph images, a stereoscopic imaging technique. This technique has been used as an instrument of both entertainment and education in the fields of education, medicine, entertainment and arts. Here, the present study aims to evaluate the effect of this technique on people through the project History on My Door conducted with the Turkish people living in Nuremberg, Germany.

Dense soft tissue 3D reconstruction refined with super-pixel segmentation for robotic abdominal surgery.

Single-incision laparoscopic surgery decreases postoperative infections, but introduces limitations in the surgeon's maneuverability and in the surgical field of view. This work aims at enhancing intra-operative surgical visualization by exploiting the 3D information about the surgical site. An interactive guidance system is proposed wherein the pose of preoperative tissue models is updated online. A critical process involves the intra-operative acquisition of tissue surfaces. It can be achieved using stereoscopic imaging and 3D reconstruction techniques. This work contributes to this process by proposing new methods for improved dense 3D reconstruction of soft tissues, which allows a more accurate deformation identification and facilitates the registration process. Two methods for soft tissue 3D reconstruction are proposed: Method 1 follows the traditional approach of the block matching algorithm. Method 2 performs a nonparametric modified census transform to be more robust to illumination variation. The simple linear iterative clustering (SLIC) super-pixel algorithm is exploited for disparity refinement by filling holes in the disparity images. The methods were validated using two video datasets from the Hamlyn Centre, achieving an accuracy of 2.95 and 1.66mm, respectively. A comparison with ground-truth data demonstrated the disparity refinement procedure: (1) increases the number of reconstructed points by up to 43% and (2) does not affect the accuracy of the 3D reconstructions significantly. Both methods give results that compare favorably with the state-of-the-art methods. The computational time constraints their applicability in real time, but can be greatly improved by using a GPU implementation.

Influence of Stereoscopic Depth on the Flanker Compatibility Effect

Modern air-traffic control displays feature complex symbology that may negatively impact operator performance efficiency. Manipulations of stereoscopic depth have been proposed as a means to declutter such displays and thereby to enhance operator performance. In this study, we employed a flanker task designed by Eriksen and Eriksen (1974) to further investigate that possibility. Participants were required to correctly respond to target letters from the sets H and K and S and C that were bordered horizontally by response compatible and response incompatible flanking letters. Using a stereoscopic imaging technique, the flanking letters were made to appear .1 and .8 cm in front of or behind the target letters, or on the same plane as the target letters. Consistent with the findings of Eriksen and Eriksen (1974), when all letters appeared on the same plane, response times (RTs) to target letters in the presence of response incompatible flanking letters were significantly elevated in comparison to RTs in the presence of response compatible flanking letters. These effects were eliminated when the flankers appeared to be slightly in front of the target letters or at both distances behind the target letters. However, the flanker effects were restored when the flankers appeared well in front of the target letters. The results suggest that the decluttering ability of stereoscopic depth is complex and dependent on the relative apparent distance between the targets and their bordering flanker elements.

A Robust Time Efficient Watermarking Technique for Stereo Images

Stereoscopic and multiview imaging techniques are used for reproducing a natural or real world scene. However, the fact that more information is displayed requires supporting technologies to ensure the storage and transmission of the sequences. Beyond these supports comes watermarking as a desirable alternative solution for copyright protection of stereo images and videos. This paper introduces a watermarking method applied to stereo images in wavelet domain. This method uses a particle swarm optimization (PSO) evolutionary computation method. The aim is to solve computational complexity problems as well as satisfy an execution time that complies with normal PCs or smart phones processors. Robustness against image attacks is tested, and results are shown.

Clinical Use of Dual Image-Guided Localization System for Spine Radiosurgery

The recently released Novalis TX linac platform provides various image guided localization methods including a stereoscopic X-ray imaging technique (ExacTrac) and a volumetric cone beam computed tomography (CBCT) imaging technique. The ExacTrac combined with the robotic six dimensional (6D) couch provides fast and accurate patient setup based on bony structures and offers "snap shot" imaging at any point during the treatment to detect patient motion. The CBCT offers a three dimensional (3D), volumetric image of the patient's setup with visualization of anatomic structures. However, each imaging system has a separate isocenter, which may not coincide with each other or with the linac isocenter. The aim of this paper was to compare the localization accuracy between Exactrac and CBCT for single fraction spine radiosurgery treatments. The study was performed for both phantom and patients (96 clinical treatments of 57 patients). The discrepancies between the isocenter between the ExacTrac and CBCT in four dimensions (three translations and one rotation) were recorded and statistically analyzed using two-tailed t-test.

Dual regularization-based image resolution enhancement for asymmetric stereoscopic images

Asymmetric stereoscopic imaging technique utilizes a pair of lower-resolution and full-resolution images to reduce the data storage requirement of stereoscopic images and videos, while maintaining fairly good quality in 3D perception. This paper proposes a resolution enhancement approach to reconstruct the original full-resolution image for this asymmetric stereoscopic system setup. The proposed approach exploits a dual regularization scheme: (i) a saliency-based regularization function is proposed to adaptively adjust the degree of regularization based on the local content of the image; and (ii) an occlusion-sensitive regularization function is proposed to exploit the correlation between the observed lower-resolution image and the observed full-resolution image in the neighboring view. Experiments are conducted to justify that the proposed approach outperforms a few conventional approaches.

TH-E-220-05: Minimization of Imaging Dose for Real-Time Respiratory Motion Monitoring during Arc Therapy

Purpose: To develop and evaluate a methodology for using hybrid MV‐kV imaging technique for real‐time respiratory motion tracking during arc therapy with minimized extra imaging dose while maintaining high 3D targeting accuracy. Methods: In our method, at the beginning 4 seconds of a typical arc delivery for tumors in the thoracic and abdominal region, the implanted marker positions are measured continuously using stereoscopic MV‐kV imaging. At later times, only treatment‐beam cine‐MV images are acquired. The 3D time‐varying marker positions are estimated by combining the 2D projection data and the correlative relationship between the directional components of marker motion established from stereoscopic imaging, with the constraint that the position minimizing the distance to the first principal component line segment is the most likely position. A multivariate linear regression method is used to predict the marker positions 310 and 460 ms in the future. To evaluate the proposed method, computer simulations were performed using over 70 hours of thoracic and abdominal tumor motion data from 46 patients. A Gaussian noise with zero mean and 0.5 mm standard deviation was added to the projected marker positions on the imagers to simulate the systemcalibration and marker detection errors. Results: The average RMS error of the 3D position estimation was 0.76 mm. At a 310 ms latency, the average overall RMS positioning accuracy was 1.23 mm. At a 410 ms latency, the error increases to 1.46 mm. Because the kV imaging is only used for a short period of time, the extra patient dose from imaging in IGRT can be reduced for at least an order of magnitude. Conclusions: The proposed clinically‐ready hybrid MV‐kV imaging method incurs minimal imaging dose to the patient as compared with other stereoscopic imaging techniques because of an informed exploitation of “dose‐free” cine‐MV imaging without sacrificing targeting accuracy.

Introducing 3-Dimensional Stereoscopic Imaging to the Study of Musculoskeletal Anatomy

The stereoscopic imaging technique is an option for a more realistic understanding of what we normally see in 2 dimensions on paper or on a screen. To produce a 3-dimensional image of an object, it is necessary to register 2 different images of the same object at the same distance and height with the use of cameras that focus on one particular point. A convergence between the left and right images is required for human vision. The distance between the camera and the images necessary to create the stereo pair should be proportional to the normal distance between the pupils. Stereoscopic or polarization techniques are used to create the images, and special glasses are required to view them. In medicine, 3-dimensional images are an extremely effective resource in the study and teaching of anatomy at both the macroscopic and microscopic levels. With advancements in technology and the emergence of new diagnostic imaging techniques and innovative therapeutic modalities, 3-dimensional images can be an excellent educational tool.

Clinical development of a failure detection‐based online repositioning strategy for prostate IMRT—Experiments, simulation, and dosimetry study

To implement and evaluate clinic-ready adaptive imaging protocols for online patient repositioning (motion tracking) during prostate IMRT using treatment beam imaging supplemented by minimal, as-needed use of on-board kV. The authors examine the two-step decision-making strategy: (1) Use cine-MV imaging and online-updated characterization of prostate motion to detect target motion that is potentially beyond a predefined threshold and (2) use paired MV-kV 3D localization to determine overthreshold displacement and, if needed, reposition the patient. Two levels of clinical implementation were evaluated: (1) Field-by-field based motion correction for present-day linacs and (2) instantaneous repositioning for new-generation linacs with capabilities of simultaneous MV-kV imaging and remote automatic couch control during treatment delivery. Experiments were performed on a Varian Trilogy linac in clinical mode using a 4D motion phantom programed with prostate motion trajectories taken from patient data. Dosimetric impact was examined using a 2D ion chamber array. Simulations were done for 536 trajectories from 17 patients. Despite the loss of marker detection efficiency caused by the MLC leaves sometimes obscuring the field at the marker's projected position on the MV imager, the field-by-field correction halved (from 23% to 10%) the mean percentage of time that target displacement exceeded a 3 mm threshold, as compared to no intervention. This was achieved at minimal cost in additional imaging (average of one MV-kV pair per two to three treatment fractions) and with a very small number of repositionings (once every four to five fractions). Also with low kV usage (approximation 2/fraction), the instantaneous repositioning approach reduced overthreshold time by more than 75% (23% to 5%) even with severe MLC blockage as often encountered in current IMRT and could reduce the overthreshold time tenfold (to < 2%) if the MLC blockage problem were relieved. The information acquired for repositioning using combined MV-kV images was found to have submillimeter accuracy. This work demonstrated with a current clinical setup that substantial reduction of adverse targeting effects of intrafraction prostate motion can be realized. The proposed adaptive imaging strategy incurs minimal imaging dose to the patient as compared to other stereoscopic imaging techniques.