Digital Camera System Research Articles

Two-phase flow characteristics of different charging structure in ignition and flame-spreading

To study the influence of flame-spreading behaviour in the ignition process of different charging structures in high-density charge chambers, a visualisation device was designed, and the ignition process of the two charging structures was researched. The flame-spreading process was observed by a high-speed digital camera system and the pressure data was recorded by a data acquisition instrument. According to the experiment, a two-dimensional axisymmetric internal ballistic two-phase flow model was established to simulate the flow process of gas in particle bed based on the Weighted Essentially Non-Oscillatory (WENO) Scheme. The results show that the flow field and flame-spreading status in different charging structures are different. In the full charging structure, the development of the flow field is regular, the flow field in the entire chamber has less fluctuation areas, and velocity vortices only generate during the development of the flow field and when it reaches the wall. However, in the partially charging structure with free space, there are many pressure fluctuation areas in the flow field in the chamber, and the flow field development is also uneven. Pulsating propagation occurs at the interface between particles and free space, which has a great influence on the whole combustion and ignition process. The research results reveal the characteristics of two-phase flow in different charging structures and provide a reference for the actual charging process.

Environmental microorganism classification using optimized deep learning model.

Rapid environmental microorganism (EM) classification under microscopic images would help considerably identify water quality. Because of the development of artificial intelligence, a deep convolutional neural network (CNN) has become a major solution for image classification. Three popular CNNs, referred to as ResNet50, Vgg16, and Inception-v3, were transferred to identify the EM images present on the Environmental Microorganism Dataset (EMDS), and EMAD was the small dataset, which only has 294 EM images with 21 EM classes. Besides data augmentation, optimizing the fully connected layer of CNN, i.e., both optimally fine-tuned neuron number and dropout rate, was adopted to enhance the performance produced by CNN. The discussions on the causes of the accuracy improved by optimization are also provided. The results showed that the Inception-v3 model obtained 84.9% of the accuracy and performed better than the other two famous CNNs. Also, the implement of data augmentation enhanced the performance of Inception-v3 on EMDS. To add to that, the optimized Inception-v3 model archived 90.5% of the accuracy, and this result demonstrated the improvement effect obtained by using genetic algorithm (GA) to optimize the fully connected layer of the Inception-v3. Therefore, the optimize Inception-v3 with data augmentation process obtained the accuracy of 92.9% and improved almost 21% higher than that obtained from the famous Vgg16. In addition, the optimized Inception-v3 would need less neurons, when compared with that of the optimized Vgg16 possibly. This optimized Inception-v3 could provide a solution to the EM classification in microscope with a digital camera system.

RAW Image Quality Evaluation Using Information Capacity

In this article, we propose a comprehensive objective metric for estimating digital camera system performance. Using the DXOMARK RAW protocol, image quality degradation indicators are objectively quantified, and the information capacity is computed. The model proposed in this article is a significant improvement over previous digital camera systems evaluation protocols, wherein only noise, spectral response, sharpness, and pixel count were considered. In the proposed model we do not consider image processing techniques, to only focus on the device intrinsic performances. Results agree with theoretical predictions. This work has profound implications in RAW image testing for computer vision and may pave the way for advancements in other domains such as automotive or surveillance camera.

Image Based Quality Inspection in Smart Manufacturing Systems: A Literature Review

Quality inspection is an important component of today’s smart manufacturing systems (SMS). Their prominence stems from the objective of manufacturing companies to i) deliver high-quality products, ii) inspire brand loyalty, iii) keep within regulations, and iv) minimize waste of resources (incl. such as employee and machine time, scrap materials) to maximize profit. There is a wide variety of quality inspection systems deployed on the shop floor utilizing different technologies, ranging from human operators to high-fidelity sensor systems to image based systems. In this work we focus on the latter, modern image-based quality inspection systems and processes. Vision based quality inspection has seen an increase in applications and academic attention over the past decade, aligned with the dawn of Industry 4.0. On the one hand, digital camera systems (including the optics, sensors, and connectivity) have become more powerful and at the same time more affordable. On the other hand, the analytics – namely artificial intelligence and machine learning algorithms – have made tremendous advancements in terms of results as well as accessibility. Most notably, deep neural networks and deep learning have elevated the potential of computer vision in quality inspection applications to the next level. In this paper, we will conduct a comprehensive literature review analysing image based quality inspection systems in SMS over the last decade. We will focus particularly on the question of how image based in-situ quality inspection of three-dimensional parts is currently conducted. The results will provide an overview of the different available image based quality inspection approaches, their benefits and challenges, as well as specific application areas and/or industries.

Effect of soil moisture on pupation behavior and inhabitation of Spodoptera frugiperda (Lepidoptera: Noctuidae)

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a persistent agricultural pest in many areas of the world, and it successfully invaded China in 2019. Like many lepidopteran insects, S. frugiperda pupates live in soil for protection under harsh environmental conditions. We conducted a serial experiment to understand the pupation behavior of S. frugiperda, as well as the effect of soil moisture on pupation. A digital video camera system was used to monitor larval pupation behavior of S. frugiperda. Four different soil moisture choices (5, 25, 50, and 80%) were used to determine the pupation location and behavior of S. frugiperda under laboratory conditions. The four-choice tests showed that most of the larvae prefer to pupate at 25–50% in saturated soil, and other few larvae burrow and pupate under dry (5%) or wet (80%) soils. In the no-choice tests, S. frugiperda larvae did not prefer the wet soil (80%) to pupate. However, soil moisture did not significantly affect the emergence rates. This study helps to increase the knowledge on pupation ecology of S. frugiperda and implies management strategies for this destructive pest.

Optically Based Hand-Held Sensor for Visualization and Quantification of Cryptosporidium Parvum

The ingestion of the protozoan parasite Cryptosporidium, resulting in the associated disease cryptosporidiosis, can cause major problems if introduced into a water supply for both animals and humans. This research focuses on the creation of a sensor to track and quantify the parasite with a digital camera system using Digital Inline Holographic Microscopy (DIHM) and software reconstruction. Since Cryptosporidium oocysts are not single celled and can be around 4–8 µm in diameter, they are easily detected with the DIHM at various depths within a 3.5 mL cuvette. As the sensor is improved by modifications, it could pick up behavior of movement and sizes of particles measured to positively identify the particle(s) being tracked as Cryptosporidium as others have achieved on Escherichia coli and other microorganisms. A significant advantage of this technique is the resulting sensor costs significantly less than traditional microscopes used in laboratory tests for detecting Cryptosporidium, or other methods like USEPA Method 1623 and can provide results within minutes. The sensor is a stellar alternative to current methods in detecting and quantifying Cryptosporidium.

Surface characteristics of particleboard produced from hydro-thermally treated wheat stalks

Surface characteristics were studied for particleboards produced from hydro-thermally treated (HTT) and non-treated (NT) wheat stalk (WS). Wood and wheat stalk particles were used as experimental materials. The wheat stalk particles were subjected to HTT at a temperature of 180 °C for 8 minutes in a steam explosion machine. HTT and NT WS particles were added at 10%, 20%, 30%, and 40% to the wood particles. The surface roughness and wettability of the produced panels were determined. The roughness measurements, average roughness (Ra), maximum roughness (Rmax), and mean peak-to-valley height (Rz) were performed using a fine stylus tracing technique. The wetting behavior of the panels was characterized by the contact angle method (goniometer technique). The contact angle (CA) measurements were obtained by using a KSV Cam-101 Scientific Instrument connected with a digital camera and computer system. Statistical analyses showed significant differences in the surface roughness and wettability of the particleboards following hydro-thermal modification. The addition of WS to the panels significantly decreased the roughness values. However, all of the HTT groups exhibited higher roughness compared to NT groups. The CA values decreased when the WS content increased. The wettability of the particleboard containing HTT WS particles was improved.

HIGH PRECISION FULLY INTEGRATED AIRBORNE DIGITAL MAPPING SYSTEMS – STATE OF THE ART AND PERFORMANCE ANALYSIS

Abstract. This paper introduces the Phase One Aerial System 150, a next generation fully integrated fully digital aerial camera system with one single digital camera head and lens which almost matches the perfect geometry of a film camera for all airborne mapping applications. It is the first true replacement for the simplicity, geometry and efficiency established by film cameras for traditional airborne mapping. Several test flights were planned to be flown with the Phase One Aerial System 150 over the Greater Denver Area, Colorado, U.S.A. during the Winter of 2020. Two lenses are planned to be used, namely: 1) 50 mm lens for wide coverage and a geometry closest to that of a film camera which is suitable for most mapping applications, and 2) 90 mm lens which provides a higher resolution (smaller GSD) and a narrower field of view which is suitable for applications where less building lean might be required. Multiple flight altitudes are flown in order to end up with a GSD of 10 cm, and 20 cm, respectively. One dual-altitude flight was planned to characterize and calibrate the integrated system including camera in-flight calibration and camera/IMU boresight calibration. The remaining flights are planned to be used to validate system accuracy and productivity as well as the mapping product accuracy. Due to the Covid-19 pandemic and poor weather, only one full dual-altitude light has been flown. Therefore, system calibration, assessment, and validation are done using this single test flight. The remainder of the test flights intended for map production evaluation and accuracy assessment will be flown during the Spring of 2020, which results will be shared with the ISPRS audience during the congress presentations.

Pyrazolo[4,3-c]pyridine-4-one (PP-4-one) Exhibits Anti-Epileptogenic Effect in Rat Model of Traumatic Epilepsy by Mammalian Target of Rapamycin (mTOR) Signaling Pathway Downregulation

BackgroundPost-traumatic epilepsy (PTE) is a common type of acquired epilepsies secondary to traumatic brain injury (TBI), accounting for approximately 10–25% of patients. The present study evaluated activity of PP-4-one against mTOR signaling activation in a rat model of FeCl2-induced post-traumatic epilepsy.Material/MethodsEpilepsy in rats was induced by injecting 10 μl FeCl2 (concentration 100 mM) at a uniform rate of 1 μl/minute. The iNOS expression was detected using a Leica microscope connected to a digital camera system. Reverse transcription polymerase chain reaction (RT-PCR) was used for determination of NR1 mRNA expression.ResultsThe post-traumatic epilepsy induced neuronal degeneration in the hippocampus and frontal cortex of the rats. Treatment with PP-4-one prevented neuronal degeneration in the hippocampus and frontal cortex in rats with post-traumatic epilepsy. The data revealed markedly higher levels of p-mTOR and p-P70S6K in rat hippocampal tissues after induction of traumatic epilepsy. Treatment of post-traumatic epilepsy rats with PP-4-one significantly suppressed p-mTOR and p-P70S6K expression, and PP-4-one treatment reduced epileptic brain injury in the rats with post-traumatic epilepsy.ConclusionsPP-4-one exhibits an anti-epileptogenic effect in the rat model of PTE by inhibiting behavioral seizures through suppression of iNOS and astrocytic proliferation. Moreover, PP-4-one treatment suppressed NR1 expression and targeted the mTOR pathway in PTE-induced rats. Thus, PP-4-one shows promise as a novel and effective therapeutic agent for treatment of epilepsy induced by PTE.

Circumscribed choroidal haemangioma: Indocyanine green angiography features on scanning laser ophthalmoscopy versus traditional digital fundus photography.

Circumscribed choroidal haemangioma (CCH) has several characteristic clinical and angiographic features. We aimed to compare indocyanine green angiography (ICG) findings of CCH captured on a traditional digital camera system (DCS) to newer scanning laser ophthalmoscopy (SLO) platforms. A total of 35 patients over a 10-year period diagnosed with CCH using ICG were included (18 imaged with DCS and 17 with SLO). On early ICG frames, intrinsic vessels were apparent in two-thirds (12/18; 67%) of the DCS group compared with all of eyes in the SLO group (p = 0.020). In addition, at maximal hyperfluorescence, most eyes imaged with DCS had a feathery appearance (16/18; 89%) compared with those in the SLO group which all (17/17; 100%) displayed a granular appearance (p < 0.001). The presence of hot spots at maximal hyperfluorescence was also more common in the SLO group (12/17; 71%) versus the DCS group (0/18; 0%) (p < 0.001). Finally, intrinsic vessels and vascular loops could be identified throughout the entire duration of the ICG in 100% of the SLO cases (17/17) versus only 11% (2/18) of DCS cases (p < 0.001). The visualization of intrinsic vessels, vascular loops, and "hot spots" in CCH is significantly enhanced with SLO compared with DCS. Many characteristic mid-late angiographic findings of CCH are more optimally visualized on SLO which may negate the need for late frames (>30 min) without compromising diagnostic accuracy.

An investigation into container constraint effects on the cavity characteristics due to high-speed projectile water entry

In this paper, the influence of container dimension constraints on the cavity expansion characteristics were preliminary investigated through series of high-speed water-entry experiments with velocity in the range of 80–470 m/s. Particular attention is given to the characteristics of cavity evolution, surface and deep closure, average cavity wall velocity and the drag coefficient under container constraints. In the test configurations, three size cylindrical-shaped containers were employed, a digital high-speed camera system is used to photograph the projectile motion and cavity expansion within the water-filled containers. Experimental results show that the cavity in a larger container will reach a larger radius and collapses later than the cavity in a much smaller container. The container size has little effect on the time of surface closure and the location of deep closure but more on the time of deep closure. Moreover, it is found that as the container size decreases to a magnitude of the cavity diameter, the projectile velocity attenuation will be strongly affected by the container constraint. The objective of the present study is to provide original dynamic data for studying the nature of hydrodynamic ram caused by the cavity expansion in subsequent work.

The Exoscope versus operating microscope in microvascular surgery: A simulation non-inferiority trial.

BackgroundThe Exoscope is a novel high-definition digital camera system. There is limited evidence signifying the use of exoscopic devices in microsurgery. This trial objectively assesses the effects of the use of the Exoscope as an alternative to the standard operating microscope (OM) on the performance of experts in a simulated microvascular anastomosis.MethodsModus V Exoscope and OM were used by expert microsurgeons to perform standardized tasks. Hand-motion analyzer measured the total pathlength (TP), total movements (TM), total time (TT), and quality of end-product anastomosis. A clinical margin of TT was performed to prove non-inferiority. An expert performed consecutive microvascular anastomoses to provide the exoscopic learning curve until reached plateau in TT.ResultsTen micro sutures and 10 anastomoses were performed. Analysis demonstrated statistically significant differences in performing micro sutures for TP, TM, and TT. There was statistical significance in TM and TT, however, marginal non-significant difference in TP regarding microvascular anastomoses performance. The intimal suture line analysis demonstrated no statistically significant differences. Non-inferiority results based on clinical inferiority margin (Δ) of TT=10 minutes demonstrated an absolute difference of 0.07 minutes between OM and Exoscope cohorts. A 51%, 58%, and 46% improvement or reduction was achieved in TT, TM, TP, respectively, during the exoscopic microvascular anastomosis learning curve.ConclusionsThis study demonstrated that experts’ Exoscope anastomoses appear non-inferior to the OM anastomoses. Exoscopic microvascular anastomosis was more time consuming but end-product (patency) in not clinically inferior. Experts’ “warm-up” learning curve is steep but swift and may prove to reach clinical equality.

Proposal of Technological GIS Support as Part of Resident Parking in Large Cities–Case Study, City of Brno

Over the last few years, there has been a significant increase in people’s dependence on passenger and freight transport. As a result, traffic infrastructure is congested, especially in big city centers and, at critical times, this is to the point of traffic collapse. This has led to the need to address this situation by the progressive deployment of Intelligent Transport Systems (ITS), which are used to optimize traffic, to increase traffic flow, and to improve transport safety, including reduction of adverse environmental impacts. In 2018, the first results of the C-Roads Platform which is a joint initiative of European Member States and road operators for testing and implementing C-ITS services in light of cross-border harmonization and interoperability (C-ROADS) Czech Republic project were put into operation in Brno, closely related to the international initiative to support the data structure for future communication between vehicles and intelligent transport infrastructure. A system of transport organization and safety was introduced in the city of Brno, which manages key information and ensures central management of partial systems of transport organization and safety. The most important part of this system is the parking organization system discussed in this article. The main objective was to streamline the parking system in the city center of Brno and in the immediate vicinity by preventing unauthorized long-term parking, ensuring an increased number of parking places for residents and visitors by increasing the turnover of parking. The aim of the research was to investigate (i) the possibility and optimal use of Geographic Information System (GIS) technology for resident parking system solutions, (ii) the integration of Global Satellite Navigation Systems (GNSS) satellite data and image data collected by cameras on the move and (iii) the possibility of using network algorithms to optimize mobile data collection planning. The aim of our study is to design and optimize the integrated collection of image data localized by satellite GNSS technologies in the GIS environment to support the resident parking system, including an evaluation of its effectiveness. To achieve this goal, a residential parking monitoring system was designed and implemented, based on dynamic monitoring of the parking state using a vehicle equipped with a digital camera system and Global Satellite Navigation Systems (GNSS) technology for measuring the vehicle position, controlled by spatial and attribute data flow from static and dynamic spatial databases in the Geographic Information System (GIS), which integrate the whole monitoring system. The control algorithm of a vehicle passing through the street network works on the basis of graph theory with a defined recurrence interval for the same route, taking into account other parameters such as the throughput of the street network at a given time, its traffic signs and the usual level of traffic density. Statistics after one year of operation show that the proposed system significantly increased the economic yield from parking areas from the original 30% to 90%, and reduced the overall violation of parking rules to only 10%. It further increased turnover and thus the possibility of short-term parking for visitors and also ensured availability of parking for residents in the historical center of Brno and surrounding monitored areas.

P056 Kefir (Lactobacillus kefiranofaciens) promotes autophagy and protects the intestinal barrier against DSS-induced colitis

Abstract Background Inflammatory bowel disease occurs when luminal antigens from microbiota stimulate the immune system of an intestinal barrier through defects in the tight junctions lead to an exacerbated response in the genetically predisposed individual. It is well known that the consumption of probiotics improves intestinal health. Specifically, the Lactobacillus sp. strains play a key role in the epithelial intestinal barrier, promote mucin secretion, better performance of tight junctions and prevent apoptosis of epithelial cells. This study aimed to evaluate the role of Kefir (Lactobacillus kefiranofaciens) on inflammation of dextran sodium sulphate (DSS)-induced colitis. Methods Forty male Wistar rats were randomised into five groups: Sham; 5% DSS-induced colitis; control Kefir; 5% DSS-induced colitis treated with Kefir; 5% DSS-induced colitis treated with Kefir + 5-ASA (125mg/kg/day) (Ethics Committee on the Use of Animals number 3627290119). The lactic culture of Kefir (Danisco Biolacta, Olstyn, Poland) was administered ad libitum per 6 days. The preparation of the matrix was carried out as follows: whole milk powder was reconstituted to 10% with distilled water and was incubated at 85°C for 15 min using a mechanical shaker. Subsequently, 20 mg freeze-dried Kefir culture was added to 100 ml of the treated milk and fermentation were carried out at 23°C for 16 h. When the desired pH of 4.6 was reached, the fermentation was stopped by cooling the flasks in ice bath and storing them under refrigeration at 4°C until utilisation. The rats were euthanised on day 9. Colonic samples were processed for transmission electron microscope (TEM) and conventional microscopy. Samples were analysed in a TEM EX II 1200 (JEOL, Japan) coupled to a digital camera system GATAN Orius (USA). Histopathological evaluation was performed by a pathologist under a light microscope. Parameters such as inflammation extent, regeneration and crypt damage were graded according to Dieleman et al.3 Statistical analysis was performed by one-way analysis of variance (ANOVA), followed by Tukey’s test using Graph Pad Prism (version 6.0). Results Kefir treatment reduces the severity of DSS-induced colitis evidenced by decreased abdominal discomfort and rectal bleeding. Histologically, there was a significant decreased of colonic damage and preservation of goblet cells (p &amp;lt; 0.0001) compared with DSS-colitis control group (Figure 1). The effect of Kefir was also verified by TEM analysis at the ultrastructural level, demonstrating the tight junctions preserved, decreased of reticulum edema and increased of autophagosomes (Figure 2). Conclusion Kefir promotes autophagy and protects the intestinal barrier against damage caused by DSS.

Effect of ZnO Nanofiller in the XLPE Matrix on Electrical Tree Characteristics

The effect of nanofillers on the electrical tree behavior of polymeric materials, such as epoxy resin and polyethylene, has been investigated. Thus, research on electrical tree behaviour is extended but limited only to pure crosslinked polyethylene (XLPE) cable. Electrical tree properties are yet to be explored under various types of nanofillers in XLPE. In this paper, the electrical tree characteristics of XLPE containing zinc oxide (ZnO) nanofiller was reported. The nanofiller concentrations in XLPE were varied to 0.5, 1.0, and 1.5 wt%. Needle-plane electrodes were employed with 2 mm gap between the electrodes. A digital camera and microscope system were used to observe the structure and growth of electrical tree in XLPE. The tree inception voltage (TIV) of XLPE increased with the addition of ZnO nanofiller. The propagation length of tree growth improved compared with the unfilled XLPE. The TIV for the samples with 0.5, 1.0, and 1.5 wt% ZnO nanofiller improved by 7.69%, 14.65%, and 7.16%, respectively, relative to the unfilled XLPE.

Multiple vehicle tracking and classification system with a convolutional neural network

This paper proposes a traffic monitoring system that detects, tracks, and classifies multiple vehicles on the road in real time using various digital image processing techniques and the process of machine learning based on a convolutional neural network (CNN). With this system, a video camera is installed on the road, and calibration is used to obtain the projection equation of the actual road on the image plane. Several image processing techniques, such as background modeling, background extraction, edge detection, and object tracking, are used to develop and implement a prototype system. The proposed system also uses a transfer learning process that is more efficient than starting CNN from scratch. This maximizes training efficiency and increases prediction accuracy in vehicle classification. Preliminary experimental results demonstrate that multiple vehicle tracking and classification are possible while calculating vehicle speed. The ultimate goal of this study is to develop a single digital video camera system with embedded machine learning process that can monitor and distinguish multiple vehicles simultaneously in multiple lanes.

Daylight-Artificial Light Integrated Scheme Based on Digital Camera and Wireless Networked Sensing-Actuation System

Automated lighting can achieve significant energy savings. A daylight-artificial light integrated system with the camera as the sensor and wireless sensor actuator networked (WSAN) system is presented here. The workplane luminance, the window luminance, and the discomfort glare position of the user are extracted from the image of the workspace captured by the camera. The findings of this paper are the usage of the camera as luminance meter and how this information is used in the control of LED dimming based on consumer comfort. A novel camera-based fuzzy controller for window blind, considering visual, and thermal comfort, is designed, based on the parameters extracted from the image, to optimize the illuminance and uniformity for a test space. The control system integrates luminaire and window blind control. The model-based design approach provides visual and thermal comfort for the consumer without compromising on energy consumption. The real time implementation of the shading and lighting integrated model, with daylight adaptation and the wireless networked sensor-actuation system is shown in this paper. The performance of the wireless networked lighting scheme is analyzed, by evaluating the energy consumption of the nodes in idle, transmit, and receive mode.

Can willow roots oxygenate leachate in vegetation filter beds?¬ a mass spectrometer investigation in Wales

Membrane inlet mass spectrometry (MIMS) was used to monitor dissolved gas concentrationsin-situ in laboratory microcosms and in a constructed willow vegetation filter bed in Walesused to treat leachate. A mini-rhizotron digital camera system was developed for use incombination with MIMS studies of gas dynamics. The major results of the studies are:-• Diurnal cycles in the concentrations of 02, CO2 and C� were shown to occur with arooted willow cutting in a stirred microcosm.• Willow beds show considerable sub-surface spatial diversity. Generally, oxygen decreaseswith depth whereas methane and carbon dioxide increase with depth. Small pockets ofgases were seen. Oxygen occurred throughout the profile.• Microbial processes follow diurnal cycles. Oxygen is released from willow roots duringdaylight. Methane and carbon dioxide accumulate during the dark.• The high degree of mixing distributes oxygenated water throughout the bed. Stopping theflow of leachate allowed conditions to become anaerobic, except in local micro-sites.These techniques appear to offer considerable potential for direct measurement of sub-surfaceenvironments in constructed wetlands, particularly in respect of the microbial processesoccurring in the bed, and the oxygenation capacity of willow vegetation filters.

New Four Points Initialization for Digital Image Correlation in Metal-Sheet Strain Measurements

Nowadays, the deformation measurement in metal sheets is important for industries such as the automotive and aerospace industries during its mechanical stamping processes. In this sense, Digital Image Correlation (DIC) has become the most relevant measurement technique in the field of experimental mechanics. This is mainly due to its versatility and low-cost compared with other techniques. However, traditionally, DIC global image registration implemented in software, such as MATLAB 2018, did not find the complete perspective transformation needed successfully and with high precision, because those algorithms use an image registration of the type “afine” or “similarity”, based on a 2D information. Therefore, in this paper, a DIC initialization method is presented to estimate the surface deformation of metal sheets used in the bodywork automotive industry. The method starts with the 3D points reconstruction from a stereoscopic digital camera system. Due to the problem complexity, it is first proposed that the user indicates four points, belonging to reference marks of a “Circle grid”. Following this, an automatic search is performed among the nearby marks, as far as one desires to reconstruct it. After this, the local DIC is used to verify that those are the correct marks. The results show reliability by reason of the high coincidence of marks in experimental cases. We also consider that the quality of mark stamping, lighting, and the initial conditions also contribute to trustworthy effects.

A Method for Calculating Bottom Backscattering Strength Using Omnidirectional Projector and Omnidirectional Hydrophone

A method of obtaining bottom backscattering strength by employing an omnidirectional projector and omnidirectional hydrophone is proposed. The backscattering strength is extracted from monostatic backscattering data. The method was adopted in an experiment conducted in the South Yellow Sea of China. The seafloor surface was relatively smooth and covered by a small quantity of shell fragments, as observed through a digital camera system. Sampling data showed that the main component of the sediment at this experimental site was fine sand. In this paper, we detail the calculation method. Preliminary results of backscattering strength as a function of grazing angle (20°–70°) in the frequency range of 6–24 kHz are presented. The measured backscattering strength increased with the grazing angle and changed more rapidly at large grazing angles (60°–70°). A comparison of the data at different frequencies reveals that the measured backscattering strength substantially rises with the increase of acoustic frequency. A fitting curve of Lambert’s law against the measured data shows that the backscattering strength deviates from Lambert’s law at large grazing angles.