A case study evaluation

Underwater georeferenced photo-transect survey was conducted on September 23 - 27, 2007 at different sections of the reef flat, reef crest and reef slope in Heron Reef. For this survey a snorkeler or diver swam over the bottom while taking photos of the benthos at a set height using a standard digital camera and towing a surface float GPS which was logging its track every five seconds. A standard digital compact camera was placed in an underwater housing and fitted with a 16 mm lens which provided a 1.0 m x 1.0 m footprint, at 0.5 m height above the benthos. Horizontal distance between photos was estimated by three fin kicks of the survey diver/snorkeler, which corresponded to a surface distance of approximately 2.0 - 4.0 m. The GPS was placed in a dry-bag and logged its position as it floated at the surface while being towed by the photographer. A total of 3,586 benthic photos were taken. A floating GPS setup connected to the swimmer/diver by a line enabled recording of coordinates of each benthic. Approximation of coordinates of each benthic photo was done based on the photo timestamp and GPS coordinate time stamp, using GPS Photo Link Software (www.geospatialexperts.com). Coordinates of each photo were interpolated by finding the gps coordinates that were logged at a set time before and after the photo was captured. Benthic or substrate cover data was derived from each photo by randomly placing 24 points over each image using the Coral Point Count excel program (Kohler and Gill, 2006). Each point was then assigned to 1 out of 80 cover types, which represented the benthic feature beneath it. Benthic cover composition summary of each photo scores was generated automatically using CPCE program. The resulting benthic cover data of each photo was linked to gps coordinates, saved as an ArcMap point shapefile, and projected to Universal Transverse Mercator WGS84 Zone 56 South.

Several scoliosis detection systems, using three-dimensional (3D) cameras or sensors, have been developed in recent years. Because these systems require specific 3D digital cameras or sensors, and the equipment is expensive, they are rarely used in many countries and regions. The development of a scoliosis screening system that uses standard two-dimensional (2D) digital cameras that come with tablet personal computers (PCs) and smartphones will facilitate the efforts made to detect scoliosis patients on a global scale. The aim of this technical note was to report on a mobile application for scoliosis screening that uses a standard 2D digital camera. The subjects were patients aged 10 years or older who visited our outpatient clinic for scoliosis or suspected scoliosis and underwent whole-spine radiography. Photographs of subjects were obtained using a standard 2D digital camera connected to a tablet PC. For analysis, we used the simplified scoliosis diagnosis support application (Cobb First, Its Corporation, Kawasaki, Japan) which operates on Windows 10 operating system (OS). When an image was imported into the application, it was displayed within a grid. The grid consisted of four columns and 40 rows and was divided into 160 areas. Each image was converted into binarized image data by demarcating skin and background color. The image of the subject was displayed as a black subject on a white background. Two types of conditions were presented to process differences in the environment versus skin color. A binarized image with a clear outline was selected. The determination was displayed as a percentage of the black area in each grid. In each row of the grid, the left and right sides of the black area were compared, and the part with the larger area with respect to the opposite side was colored and displayed. Depending on the ratio of the difference, it was possible to display green, yellow, and red. If this mobile application is available for clinical use, it has the potential to improve the accuracy of screening by physicians and nurses. Furthermore, it may also be used globally to check for possible evidence of scoliosis at home to facilitate the early detection of patients who require a medical checkup for scoliosis. Although it is essential to perform a radiographic examination for the definitive diagnosis of scoliosis, our future goal is to limit radiation exposure and replace a radiologic method with one based on a tablet PC or smartphone. A mobile application using a standard 2D digital camera may improve the accuracy of screening scoliosis by physicians and may have global application in home environments.

Selectivity for local orientation information in visual mirror symmetry perception

The inter- and intra-annual snow cover distribution in the Zackenbergdalen valley, north-east Greenland, was monitored using images from a digital camera. The Digital Camera Images (DCIs) provide-in contrast to satellite images-data with a high temporal and spatial resolution at low cost. The digital camera, positioned on a rock 500 m above sea level (asl), automatically takes oblique photographs of the valley. To obtain the necessary area consistency for mapping purposes, the DCIs are transformed into digital orthophotos. Snow cover mapping is performed using these orthophotos. In order to suppress errors due to illumination effects, a normalized index based on red, green and blue (RGB) values was developed. The index can be used as an analogue to the Normalized Difference Snow Index (NDSI), commonly used in combination with Landsat Thematic Mapper (TM) images. During the melt-off season, a maximum of 10-15 Landsat TM passes occur over the Zackenberg area. For the 1999 meltoff season only three cloud-free TM images were usable for snow-mapping, while 46 DCIs were suitable for this purpose. Analysis of 1998 and 1999 data shows that the snow cover in Zackenbergdalen decreases gradually during the melt-off season. The resulting depletion curves have a 'laterally reversed S-shaped' form, which depends on the initial amount of snow in the area, the temperature during the melt-off season and altitudinal level.

Regional surveys will have a high demand for coverage. To adequately cover a large area while retaining high resolution, mosaics of the area from a variety of scenes can be created. This paper describes a mosaicking procedure that consists of a series of processing steps used to combine multiple aerial images. These images were taken from CropCam unmanned aerial platform flight missions over the desired area to quickly map a large geographical region. The results of periodic processing can be compared and analyzed to monitor a large area for future research or during an emergency situation in the covered area. Digital imagery captured from the air has proven to be a valuable resource for studying land cover and land use. For this study, airborne digital camera images were chosen because they provide data with a higher spatial resolution for trying to map a small research area. On board the UAV autopilot, images were captured from an elevation of 320 meters using a standard digital camera. When compared to other airborne studies, this technique was less expensive and more cost effective. According to this study, onboard a UAV autopilot, a digital camera serves as a sensor, which can be helpful in planning and developing a limited coverage area after mosaicking

We describe an infrastructure based on an existing, commercially available, GSM mobile phone for achieving connectivity between digital cameras and an Internet Website. Pictures are loaded from a standard digital camera, or compact flash card, by an embedded appliance, which establishes the Internet connection and controls the transfer of pictures from the camera to a remote Website. Detailed descriptions are given of this picture transfer appliance and of a typical Website infrastructure to store and manage the pictures and provide end-user services.

This paper describes a new approach to color image rendering for mixed reality applications. The approach has two steps. The first uses neural network based photometric stereo to obtain both a 3D shape model and color reflectance factors simultaneously. The second uses neural network based image rendering to generate realistic virtual images for arbitrary viewpoint and direction of light source. The proposed approach achieves high quality 3D modeling of real objects and subsequent virtual image rendering based on empirical measurements obtained in a simple experimental environment. The approach is empirical using only a standard digital camera and light sources. Assumptions about surface reflectance are reasonably generic. Experiments using real data are demonstrated.

This paper presents a novel method for 3D surface reconstruction that uses polarization and shading information from two views. The method relies on polarization data acquired using a standard digital camera and a linear polarizer. Fresnel theory is used to process the raw images and to obtain initial estimates of surface normals, assuming that the reflection type is diffuse. Based on this idea, the paper presents two novel contributions to the problem of surface reconstruction. The first is a technique to enhance the surface normal estimates by incorporating shading information into the method. This is done using robust statistics to estimate how the measured pixel brightnesses depend on the surface orientation. This gives an estimate of the object material reflectance function, which is used to refine the estimates of the surface normals. The second contribution is to use the refined estimates to establish correspondence between two views of an object. To do this, a set of patches are extracted from each view and are aligned by minimizing an energy functional based on the surface normal estimates and local topographic properties. The optimum alignment parameters for different patch pairs are then used to establish stereo correspondence. This process results in an unambiguous field of surface normals, which can be integrated to recover the surface depth. Our technique is most suited to smooth, non-metallic surfaces. It complements existing stereo algorithms since it does not require salient surface features to obtain correspondences. An extensive set of experiments, yielding reconstructed objects and reflectance functions, are presented and compared to ground truth.

Feasibility of digital image correlation for detection of cracks at fastener holes

Background:The main drawbacks of zirconia are its high refractive index and opacity. This study aimed to assess the effect of sintering temperature on the translucency of Ivoclar e. max ZirCAD (IEZ), and White Peaks Symphony (WPS) zirconia blocks.Materials and Methods:In this in vitro experimental study, 30 IEZ and 30 WPS zirconia blocks measuring 10 mm × 10 mm × 1 mm were prepared and underwent sintering in three subgroups at 1440°C, 1500°C, and 1530°C. The specimens were then photographed against a black and a white background with a standard digital camera. The L*, a*, and b* color parameters were measured using Adobe Photoshop software, and translucency was calculated. Data were analyzed using one-way ANOVA and Tukey’s test (P < 0.05).Results:In both the IEZ and WPS groups, the maximum and minimum translucency parameters were recorded in 1530°C and 1440°C subgroups, respectively. The difference in the mean translucency was significant among the three subgroups of each zirconia group (P < 0.001). The mean translucency of WPS zirconia was significantly higher than that of IEZ zirconia (P < 0.01), and maximum difference was noted at 1500°C sintering temperature.Conclusion:Increasing the sintering temperature from 1440°C to 1530°C can significantly increase the translucency of IEZ and WPS zirconia blocks, and can be considered to improve the quality of zirconia restorations.

One of the strongest limiting factors in close range photogrammetry (CRP) is the depth of field (DOF), especially at very small object distance. When using standard digital cameras and lens, for a specific camera – lens combination, the only way to control the extent of the zone of sharp focus in object space is to reduce the aperture of the lens. However, this strategy is often not sufficient; moreover, in many cases it is not fully advisable. In fact, when the aperture is closed down, images lose sharpness because of diffraction. Furthermore, the exposure time must be lowered (susceptibility to vibrations) and the ISO increased (electronic noise may increase). In order to adapt the shape of the DOF to the subject of interest, the Scheimpflug rule is to be applied, requiring that the optical axis must be no longer perpendicular to the image plane. Nowadays, specific lenses exist that allow inclining the optical axis to modify the DOF: they are called tilt-shift lenses. In this paper, an investigation on the applicability of the classic photogrammetric model (pinhole camera coupled with Brown’s distortion model) to these lenses is presented. Tests were carried out in an environmentally controlled metrology laboratory at the National Research Council (NRC) Canada and the results are hereafter described in detail.

Metal nanoparticles based lab-on-paper for phenolic compounds evaluation with no sample pretreatment. Application to extra virgin olive oil samples

Quantitation of thin-layer chromatography (TLC) using image analysis is attractive for its low cost and convenience. The image analysis is investigated by designing a digital imaging system with simple equipment, developing an image analysis software based on our algorithm, and validated the system in the TLC quantitative assay of cichoric acid present in Echinacea purpurea (L.) Moench. TLC used a polyamide thin-layer plate with chloroform-methanol formic acid-water (3:6:1:1) as the mobile phase and 3% (m/v) aqueous aluminum chloride solution as the visualization reagent. Images are acquired with a standard digital camera under a UV viewing lamp (365 nm) in a dark room. The three-dimensional gray scale digital image dataset (x, y, gray) is reduced to two-dimensional dataset (distance, accumulative gray) and then plotted as a curve. The area under the peak corresponding to the cichoric acid spot is integrated and used for quantitation. The whole method was validated by the assay tests of detection limit, calibration curve, repeatability, reproducibility, and recovery. The results showed that our digital imaging method and image analysis algorithm were applicable for the quantification of TLC. The whole method is convenient, efficient, and moderately accurate for the quantitative assay of cichoric acid present in Echinacea purpurea (L.) Moench.

To increase the stability of enzymes in organic solvents, they may be immobilized in a polymer matrix suspended in the solvent. It is important to know that all the immobilized enzyme particles are completely suspended in order to ensure an efficient particle-liquid mass transfer coefficient while putting as little energy into the system as necessary so that the particles are not harmed. A novel noninvasive method based on photometry and analysis of images taken with a standard digital camera is presented to estimate a mean extinction in different parts of the reactor and to finally determine the just suspending stirring speed (NJS) for complete suspension in an objective way. With this optical method, six different reactor configurations were compared based on the maximum local energy dissipation rate. Here, the 90° bladed stirrer with a flat bottom proved to be one of the best configurations for attaining complete suspension with low maximum local energy dissipation rate.

At present, detecting structural defects such as cracking and corrosion before they become critical is largely achieved by time consuming techniques such as eddy current and ultrasonic testing. These techniques require point‐by‐point scanning over the area to be tested. Digital Image Correlation could provide a cheaper and quicker testing technique. It works by correlating images of the structure surface in unloaded and loaded states taken with a standard digital camera, giving the displacement and strain fields. The specific case of a crack at a hole in an aluminium plate was investigated. It was found that the strain concentration around the crack tip is too localised to detect; however the displacement jump across the crack could be seen. This technique allows the cracks to be detected and would allow rapid testing of a structure if it can easily be loaded.