Shading Method Research Articles

Accurate Analysis of the Spatial Pattern of Reflected Light and Surface Orientations Based on Color Illumination

3D Recovery approaches require a variety of clues to obtain shape information. The shape from shading (SFS) method uses shading information in images to estimate depth maps. Although shading contains detailed information, it causes some well-known ambiguities such as convex-concave ambiguity. In this study, a system installation, using red, green, and blue illumination, and an algorithm, processing reflections on the surface, were proposed for the accurate analysis of surface orientations, and ambiguity problems. Surface orientations, erroneously predicted by six different methods, were improved by implementing the proposed system. Consequently, the correct orientation of the surface points was determined by removing the ambiguities in images taken without considering the location of illumination, and all the tested methods provided successful results using the proposed system.

Automatic Detection and Classification of Defective Areas on Metal Parts by Using Adaptive Fusion of Faster R-CNN and Shape From Shading

Computer vision and deep learning approaches have an important role in industrial inspection systems. Computer vision technology is essential for fast, defect-free control of products in the production line. The importance of the computer vision concept is recognized when the problems of the classical methods are taken into consideration. Metallic defect detection is a challenging problem as metal surfaces are easily affected by environmental factors such as lighting and light reflection. Since traditional detection algorithms are inefficient in complex problems, we propose a novel method to detect and classify metal surface defects, such as cracks, scratches, inclusion, etc. The type and location of defects were detected by the Faster Regional Convolutional Neural Network (Faster R-CNN), combined with the Shape From Shading (SFS) method, which can extract surface characteristics. The Northeastern University (NEU) surface defect database was used for defective samples. The proposed algorithm has also been tested on an unlabeled dataset (KolektorSDD2/KSDD2) to show labeling performance. The results on both labeled and unlabeled datasets have demonstrated state-of-the-art performance in automatic defect detection, classification, and labeling. The proposed method has satisfactory results for the detection of defects on the metal surface, and the mean average precision is 0.83. The average precision of crazing, pitted surface, patches, scratches, inclusion, and rolled-in scale are 0.96, 0.93, 0,89, 0.80, 0.72, and 0.71, respectively.

The unique physical shading pattern of Rayleigh scattering for the generally improved detection of scattering particles.

The Rayleigh scattering method is a rising analytical technique because of its high sensitivity and simple operability in the detection of scattered particles. Herein, an efficient and facile physical shading method (covering the cuvette) based on the Rayleigh scattering pattern was developed, which exhibited overall promotion of sensitivity, linearity, detection limit, precision and accuracy because of its greatly reduced background noise upon measurement even if complicated chemical reagents and instruments were not involved. Protein, as a common scattering particle, is a direct or indirect expression of an organism's state of life. Thus, considering the simple and cost-effective features of the shading treatment, a combination strategy based on the probe was adapted to further enhance the performance of protein detection (the limit of detection (3σ) was reduced by at least 20 times, using Eriochrome Black T as a probe), and the possible reasons for the improvement were deduced theoretically. Furthermore, the technology was successfully applied to detect protein in human urine, giving consistent results. In general, this improvement strategy can be handily integrated into most detection systems based on Rayleigh scattering, and its realization delineates a blueprint for the rapid development of sensors.

Perceptual model for adaptive local shading and refresh rate

When the rendering budget is limited by power or time, it is necessary to find the combination of rendering parameters, such as resolution and refresh rate, that could deliver the best quality. Variable-rate shading (VRS), introduced in the last generations of GPUs, enables fine control of the rendering quality, in which each 16×16 image tile can be rendered with a different ratio of shader executions. We take advantage of this capability and propose a new method for adaptive control of local shading and refresh rate. The method analyzes texture content, on-screen velocities, luminance, and effective resolution and suggests the refresh rate and a VRS state map that maximizes the quality of animated content under a limited budget. The method is based on the new content-adaptive metric of judder, aliasing, and blur, which is derived from the psychophysical models of contrast sensitivity. To calibrate and validate the metric, we gather data from literature and also collect new measurements of motion quality under variable shading rates, different velocities of motion, texture content, and display capabilities, such as refresh rate, persistence, and angular resolution. The proposed metric and adaptive shading method is implemented as a game engine plugin. Our experimental validation shows a substantial increase in preference of our method over rendering with a fixed resolution and refresh rate, and an existing motion-adaptive technique.

Semi-Transparent Organic Photovoltaics Applied as Greenhouse Shade for Spring and Summer Tomato Production in Arid Climate

Recognizing the growing interest in the application of organic photovoltaics (OPVs) with greenhouse crop production systems, in this study we used flexible, roll-to-roll printed, semi-transparent OPV arrays as a roof shade for a greenhouse hydroponic tomato production system during a spring and summer production season in the arid southwestern U.S. The wavelength-selective OPV arrays were installed in a contiguous area on a section of the greenhouse roof, decreasing the transmittance of all solar radiation wavelengths and photosynthetically active radiation (PAR) wavelengths (400–700 nm) to the OPV-shaded area by approximately 40% and 37%, respectively. Microclimate conditions and tomato crop growth and yield parameters were measured in both the OPV-shaded (‘OPV’) and non-OPV-shaded (‘Control’) sections of the greenhouse. The OPV shade stabilized the canopy temperature during midday periods with the highest solar radiation intensities, performing the function of a conventional shading method. Although delayed fruit development and ripening in the OPV section resulted in lower total yields compared to the Control section (24.6 kg m−2 and 27.7 kg m−2, respectively), after the fourth (of 10 total) harvests, the average weekly yield, fruit number, and fruit mass were not significantly different between the treatment (OPV-shaded) and control group. Light use efficiency (LUE), defined as the ratio of total fruit yield to accumulated PAR received by the plant canopy, was nearly twice as high as the Control section, with 21.4 g of fruit per mole of PAR for plants in the OPV-covered section compared to 10.1 g in the Control section. Overall, this study demonstrated that the use of semi-transparent OPVs as a seasonal shade element for greenhouse production in a high-light region is feasible. However, a higher transmission of PAR and greater OPV device efficiency and durability could make OPV shades more economically viable, providing a desirable solution for co-located greenhouse crop production and renewable energy generation in hot and high-light intensity regions.

Organic Farming Practices and Shade Trees Reduce Pest Infestations in Robusta Coffee Systems in Amazonia.

Coffee agroforestry systems could reconcile agricultural and environmental objectives. While pests and diseases can reduce yield, their interactions with shade and nutrition have been rarely researched, and are particularly lacking in perennial systems. We hypothesized that intermediate shade levels could reduce coffee pests while excess shade could favor fungal diseases. We hypothesized that organic rather than mineral fertilization would better synchronize with nutrient uptake and higher nutrient inputs would be associated with reduced pest and disease damage due to higher plant vigor, yet effects would be less obvious in shaded plots as coffee growth would be light-limited. Using three-year-old trees of Coffea canephora var. Robusta (robusta coffee) in the Ecuadorian Amazon, we compared a full-sun system with four shading methods creating different shade levels: (1) Myroxylon balsamum; (2) Inga edulis; (3) Erythrina spp.; or, (4) Erythrina spp. plus Myroxylon balsamum. Conventional farming at either (1) moderate or (2) intensified input and organic farming at (3) low or (4) intensified input were compared in a split-plot design with shade as the main plot factor and farming practice as the sub-plot factor. The infestation of the following pests and disease incidences were evaluated monthly during the dry season: brown twig beetle (Xylosandrus morigerus), coffee leaf miner (Leucoptera coffeella), coffee berry borer (Hypothenemus hampei), anthracnose disease (Colletotrichum spp.), thread blight (Pellicularia koleroga), and cercospora leaf spot (Cercospora coffeicola). Coffee berry borer and brown twig beetle infestation were both reduced by 7% in intensified organic treatments compared to intensified conventional treatments. Colonization of coffee berry borer holes in coffee berries by the entomopathogenic fungus Beauveria bassiana was also assessed. Brown twig beetle infestation was significantly higher under full sun than under Inga edulis, yet no other shade effects were detected. We demonstrate for the first time how intensified input use might promote pest populations and thus ultimately lead to robusta coffee yield losses.

Fracture Extraction from Smooth Rock Surfaces Using Depth Image Segmentation

Due to the diversity of mineral particle features in rock, including sizes, shapes, arrangements, and structural connections, the color image of the rock sample surface at laboratory scale is quite complex. Thus, unacceptable misjudgement and information loss often occur when the traditional image processing algorithms are adopted. To improve the accuracy of fracture extraction, a method based on image processing algorithms is proposed in this paper to extract fractures from 3D point clouds. First, a high-precision original depth image is generated by gridding the rock surface point cloud data with the Kriging interpolation. The hill shading method is then applied to further clarify the fractures. Finally, the fractures are extracted from depth images and compared with color images. The results show that the integrity of the fracture skeleton is significantly improved and the error rate is reduced. In combination with color images, the physical fractures and other fracture-like features can be distinguished. The proposed method provides a new idea for extracting fractures in various destructive experiments on rocks, and may be developed for recognition of discontinuities at typical engineering scale.

Hunger games search: Visions, conception, implementation, deep analysis, perspectives, and towards performance shifts

A recent set of overused population-based methods have been published in recent years. Despite their popularity, most of them have uncertain, immature performance, partially done verifications, similar overused metaphors, similar immature exploration and exploitation components and operations, and an insecure tradeoff between exploration and exploitation trends in most of the new real-world cases. Therefore, all users need to extensively modify and adjust their operations based on main evolutionary methods to reach faster convergence, more stable balance, and high-quality results. To move the optimization community one step ahead toward more focus on performance rather than change of metaphor, a general-purpose population-based optimization technique called Hunger Games Search (HGS) is proposed in this research with a simple structure, special stability features and very competitive performance to realize the solutions of both constrained and unconstrained problems more effectively. The proposed HGS is designed according to the hunger-driven activities and behavioural choice of animals. This dynamic, fitness-wise search method follows a simple concept of “Hunger” as the most crucial homeostatic motivation and reason for behaviours, decisions, and actions in the life of all animals to make the process of optimization more understandable and consistent for new users and decision-makers. The Hunger Games Search incorporates the concept of hunger into the feature process; in other words, an adaptive weight based on the concept of hunger is designed and employed to simulate the effect of hunger on each search step. It follows the computationally logical rules (games) utilized by almost all animals and these rival activities and games are often adaptive evolutionary by securing higher chances of survival and food acquisition. This method's main feature is its dynamic nature, simple structure, and high performance in terms of convergence and acceptable quality of solutions, proving to be more efficient than the current optimization methods. The effectiveness of HGS was verified by comparing HGS with a comprehensive set of popular and advanced algorithms on 23 well-known optimization functions and the IEEE CEC 2014 benchmark test suite. Also, the HGS was applied to several engineering problems to demonstrate its applicability. The results validate the effectiveness of the proposed optimizer compared to popular essential optimizers, several advanced variants of the existing methods, and several CEC winners and powerful differential evolution (DE)-based methods abbreviated as LSHADE, SPS_L_SHADE_EIG, LSHADE_cnEpSi, SHADE, SADE, MPEDE, and JDE methods in handling many single-objective problems. We designed this open-source population-based method to be a standard tool for optimization in different areas of artificial intelligence and machine learning with several new exploratory and exploitative features, high performance, and high optimization capacity. The method is very flexible and scalable to be extended to fit more form of optimization cases in both structural aspects and application sides. This paper's source codes, supplementary files, Latex and office source files, sources of plots, a brief version and pseudocode, and an open-source software toolkit for solving optimization problems with Hunger Games Search and online web service for any question, feedback, suggestion, and idea on HGS algorithm will be available to the public at https://aliasgharheidari.com/HGS.html.

Fluid Reconstruction and Editing from a Monocular Video based on the SPH Model with External Force Guidance

AbstractWe specifically present a general method for monocular fluid videos to reconstruct and edit 3D fluid volume. Although researchers have developed many monocular video‐based methods, the reconstructed results are merely one layer of geometry surface, lack of accurate physical attributes of fluids, and challenging to edit fluid. We obtain a high‐quality 3D fluid volume by extending the smoothed particle hydrodynamics (SPH) model with external force guidance. For reconstructing fluid, we design target particles that are recovered from the shape from shading (SFS) method and initialize fluid particles that are spatially consistent with target particles. For editing fluid, we translate the deformation of target particles into the 3D fluid volume by merging user‐specified features of interest. Separating the low‐ and high‐frequency height field allows us to efficiently solve the motion equations for a liquid while retaining enough details to obtain realistic‐looking behaviours. Our experimental results compare favourably to the state‐of‐the‐art in terms of global fluid volume motion features and fluid surface details and demonstrate our model can achieve desirable and pleasing effects.

3D augmented fundus images for identifying glaucoma via transferred convolutional neural networks.

Glaucoma is a chronic and irreversible retinopathy threatening the vision of millions of patients around the world. Its early diagnosis and treatment can help to prolong the period of sight deterioration from no visual impairment to blindness, whereas the screening and diagnosis of glaucoma in clinical remains challenging because some key assessment criteria like cup-to-disc ratio is limited by subjective analysis and intra- and inter-observer variability. This paper exploits the potential of new augmented image data of the optic nerve head (ONH) combining with the latest deep learning networks to achieve better diagnosis of glaucoma. This paper explores the potential value of additional three-dimensional topographic map of the optic nerve head proceeded by the latest deep learning approaches, i.e. convolutional neural networks to improve the diagnosis efficiency. Specifically, 3D topography map of the ONH and RGB fundus image has been used to train the transferred AlexNet and VGG-16 networks. The diagnostic performance is compared to those achieved by using the 2D fundus images only. The 3D topographic map of ONH reconstructed from the shape from shading method provides better visualization of the structure of optic cup and disc. These new enhanced dataset was employed to train the proposed deep learning networks and finally achieve diagnostic accuracy of 94.3% which is superior to the networks trained via 2D conventional images. Employing the deep learning neural networks with augmented 3D images can increase the accuracy of automatic separating glaucoma and non-glaucoma fundus images. It may be used as an objective tool in developing computer assisted diagnosis systems for assessment of glaucoma.

Designing a learning media based on video animation for patisserie learning

Video animation is a perfect tool as a medium in the learning process in class. The purpose of this study is to design video animations for patisserie learning in vocational education. In particular, patisserie learning requires students to have skills in practicing patisserie dishes. So it requires a companion learning facility when outside the classroom with effective and efficient learning methods such as presenting manufacturing product tutorials with explanations and clear steps, no need to use internet access or training courses to learn them. This “Patiseri Product” animated video was created using the rigging bone and cell shading method with a 2-Dimensional model, which has a duration of 03 minutes 47 seconds, with the extension specification .mp4, video resolution of 1280×720, and a frame rate of 24 fps. In making the animation, using Moho Anime Studio software to create animations, then Adobe Illustrator, CorelDraw, and Photoshop, to make modeling, and Adobe After Effects for video editing. The conclusion of the research shows that the application of animation video learning media can be used to convey patisseries material that is in accordance with special needs that are in accordance with learning, and has fulfilled the expected concept.

Developing animated video for maincourse learning

This study aims to design video animation for maincourse learning in vocational education, especially the learning maincourse which requires students to have skills in practicing maincourse dishes. It requires a companion learning facility when it take place in the outside of the classroom by using effectively and efficiently learning methods such as presenting maincourse dishes with clearly explanation and steps which is does not need to use internet access or training courses to learn them. This “Maincourse Dish” animated video is created using the rigging bone and cell shading method with 2 Dimensional model, which has a duration of 03 minutes 47 seconds, with the mp4 extension, it is used 1280x720 video resolution, and a frame rate of 24 fps. In making the animation, it is used Moho Anime Studio software to create animations, then Adobe Illustrator, CorelDraw, and Photoshop, to make modeling, and Adobe After Effects for video editing. This animated video can be a learning media for the Maincourse subject for the student’s advantage in learning material, especially the practice of making poultry-based maincourse dishes.

Model-based analysis of shading losses in ground-mounted photovoltaic power plants

Ground-mounted PV plants with multiple parallel mounting structure rows became the most common type of PV systems, where the shading of the adjacent rows results in significant energy losses. This paper presents a detailed modelling method of the inter-row shading to calculate irradiance distribution along the width of the PV rows. A modification of the Hay transposition model is proposed to account for the shading of the sky diffuse, circumsolar, and ground-reflected irradiance components. The effect of the uneven irradiance on the power output is considered by the cellwise calculation and aggregation of the I-V characteristics. The method is demonstrated by a case study, where the annual energy production and the reflection, shading, and cable losses are calculated for different string arrangements and row spacings. The proposed detailed shading model is compared to a simple shading calculation, where only the shading of the beam irradiance is considered. This simple method underestimates the shading losses by 50–80%, which underlines the importance of the proper calculation of the diffuse irradiance masking losses. The electrical mismatch losses due to the shading are compared for different string arrangements, where the best arrangement is also influenced by the number of the maximum power point trackers. As a general conclusion, the modules at the same height should be connected to the same string to minimise the shading losses. The presented method can improve the accuracy of PV simulations and the optimisation of the shading-related design parameters, like the module orientation and row spacing.

Assessing walkability in hot arid regions: the case of downtown Abu Dhabi

Regarded as critical infrastructure for a city’s planning and design, pedestrian facilities are considered to be crucial to the health and economic well-being of a city’s inhabitants. This study assesses the walkable environment of two urban neighborhoods in Abu Dhabi’s main island. The research aims at providing the primary data required to facilitate the development of policies, design strategies, and systems that will support sustainable walking environments throughout the Emirate. Specifically, the study examines the walking behavior of the users of two neighborhoods in Abu Dhabi. The following questions were explored: (1) What patterns of walking behavior are observable in the street, and what are their diurnal and seasonal rhythms? (2) What potential reasons could explain the observed walking behavior? (3) To what extent do the built environment and climate affect walking in Abu Dhabi? (4) What particular strategies could be adopted to encourage walking in Abu Dhabi? Data collection and analysis tools include the following: (1) Geographic Information Systems (GIS), (2) fieldwork, and (3) qualitative data assembled from a survey questionnaire. Survey results presented walking as a widely used form of non-motorized transportation for both leisure and utilitarian purposes among blue-collar employees working in the service and retail sectors. Transportation, entertainment, physical fitness, and health were reported as major reasons for walking. Although participants’ walking patterns were not significantly affected by climate, respondents reported that weather was the main source of discomfort while walking. Policy and design changes, infrastructure enhancement, and potential shading methods are proposed to enhance the walking experience.

Effects of Different Drying Methods on the Contents of Nine Components and Immunomodulatory Activities of Four Components in Osmamthus fragrans Flowers

The effects of drying methods on the contents of four nonvolatile and five volatile components and the immunoregulatory activities of four components in Osmamthus fragrans flowers were investigated. In general, microwaving preserved more nonvolatile components than the other methods, while the sun or shade method preserved more volatile components. Nonvolatile components such as salidroside and acteoside and volatile ingredients such as linalool and linalool oxide exhibited better immunoregulatory activity than the other ingredients. Taken together, O. fragrans flowers dried by microwaving resulted in the best immunoregulatory activity. This study provides evidence for the optimal drying method for O. fragrans flowers as food and medicine.

Smoke shade as a historic proxy for elemental carbon

The blackness of aerosol filter samples, meant as a proxy for particulate mass concentration, is the earliest parameter for which monitoring data exist. The smoke shade method (developed in the late 1910s) was the standardised approach to collect samples. The blackness was visually appraised by a comparison with a set of reference sheets covered with an increasing number of layers (shades) of a suspension of carbon black (ink). Samples were assigned a shade number (SN) according to the number of shades of ink on the reference sheet with a corresponding blackness. Automated hourly sampling started in 1921. After World War II, the blackness was measured with a reflectometer and light absorption was translated to the parameter British Smoke (BrS). One unit of SN was equivalent to a specific loading of BrS of 8 μg cm−2. BrS in turn is a proxy for elemental carbon (EC) as we showed in an earlier publication, where we found that a value of BrS of 8 μg cm−2 corresponded to an EC load of 1.4 μg cm−2. SNs can thereby be translated to historic EC loadings/concentrations. In an evaluation of SN-data, we noticed that average pre-war values were mostly at the lower detection limit (one SN) and overestimated because reference sheets faded over time. Data for smog periods with their elevated SNs, however, are quite reliable and can be used for exposure estimates. After World War II, daily sampling resulted in higher filter loadings and reliable average values. Wintertime concentrations corresponding to up to 100 μg m−3 EC were reached. On the other hand, the increased loadings due to the long sampling times resulted in a decrease of the upper limit of detection to an extent that it was exceeded at most of the measuring stations during the “Great Smog” of London in 1952. In this study, we analysed SN data from this episode in depth. At one measuring site, precautions were taken to minimise the loading by using a large filter, but even then the maximum SN was at the upper limit of detection. From a one-to-one relation of BrS and gravimetric mass, established during later smog periods, we deduced that the maximum 2-day mass concentration of EC must have been around 1000 μg m−3. This value is twenty times the new EU-limit for workplace EC exposure (EU 2019) and the 24-h ambient PM10 mass concentration.

Thermal influence caused by the vertical distribution of reflected solar radiation and re‐radiation on the building in various climate areas and its solar shading method

AbstractMost houses in Japan have the floor‐length windows to take the natural light into the room. Reflected solar radiation and Re‐radiation from the ground (Reflection) enter through the window and increase the cooling load, therefore reducing reflection to the building is necessary. We focused that reflection is greatly affected by the ground surface, its heat flux may vary depending on the height from the ground. This study presented the thermal influence by the vertical distribution of reflection on the building in various climate areas and considered the solar shading method based on that distribution. The calculation results using Sol‐Air Temperature showed that the incident heat flux of reflection increased on the lower part of the building surface, and the vertical distribution of reflection existed in various areas. We propose to shield up to the lower half part of the building as a solar shading method considering the vertical distribution of reflection. This method could be able to shield most of reflection and incorporate natural light from the top half of the window to ensure room brightness and view, that is expected to be effective in improving indoor comfort and reducing the load of cooling and lighting.

Simplified Numerical Model for Analyzing the Effects of the Urban Heat Island upon Low-Rise Buildings by Using a Free-License Thermal Simulation Program

In this document, the thermal effect of a heat island upon an urban area and its surrounding low-rise buildings is analyzed with the building thermal simulation program EnergyPlus and its EnergyPlus weather files (EPW). By using a top-down approach, a simplified numerical model is developed, which is used to simulate the urban heat island effect, and that deals with the performance of various cooling methods according to the physical, urban, and climatic characteristics of the urban site. The calculated results of outdoor air temperature considering the heat island effect achieve good agreement with the already-published results. Then, different methods of shading and cooling, varying physical values such as urban thermal transmittance, and urban thermal absorption are applied in order to find the most influencing feature upon the indoor temperature drop into a simulation loop. With this, it is found that a maximum average decrease of indoor temperature of 5.1 °C can be achieved. Furthermore, carrying out a sensitivity analysis, it is found that the albedo of both building surface and urban layout is the most influencing parameter onto the indoor thermal comfort. With this, it is expected to have a reliable model that helps to understand the urban heat island effect in a simple and cheap manner and in terms of the indoor thermal comfort of its surrounding buildings.

차광형태와 기간이 천궁의 고온피해 경감에 미치는 효과

Background: Cnidium officinale is a medicinal crop sensitive to high temperature. It is necessary to develop environment control technology that can reduce environmental stresses such as high temperature. This study was conducted to develop technology for stable production of Cnidium officinale by reducing damage owing to high temperature by applying shading treatment of varying duration, and structure.BRMethods and Results: Black shading nets were used from May to September or November; shading structures such as pillar, flat roof, and tunnel type structures were installed. Environmental changes, rate of photosynthesis, and growth characteristics were investigated. The shading treatment reduced temperature by 3℃. The rate of photosynthesis and yield with shading treatment were higher by 134% and 127%, respectively, than those with full sunlight. The ratio of shading area ranged from 50% to 71% according to the type of shading structure. The effect of environmental control on growth varied depending on the type of shading structure.BRConclusions: The shading treatment reduced damage owing to high temperature, shading rate of 55% - 75% was recorded between the period May - September, and the flat roof type shading structure was considered the most suitable among shading methods.

Tooth shade analysis and selection in prosthodontics: A systematic review and meta-analysis.

Aim:To evaluate the methods of the dental shade selection and provide a summary of different factors affecting the shade selection.Design and Setting:The systematic review and meta-analysis.Materials and Methods:The electronic search of the peer-review articles between 2002 and 2018 was carried out the by using the PRISMA guidelines. A total twenty-one studies related to the visual shade methods, instrumental shade methods, and the factors affecting the shade selections was evaluated. The search strategy was based on the PICOS framework.Statistical Analysis:There was statistically significant heterogeneity (Q = 1038.1518, df = 20, and P < 0.0001). The statistics of fixed-effect model reported an MD of − 0.0970 (95% CI = −0.1391, −0.0549). The random-effect model reported an MD of − 0.0862 (95% CI = −0.5866, 0.4142).Result:The review evaluated the 21 studies of tooth colour science that met with the inclusion criteria and search criteria. The meta-analysis of the 21 combined studies reported acceptable homogeneity (i2 = 98%) which indicates a statistically significant difference between the treatment and control groups.Conclusion:The VES spectrophotometer reported the highest accuracy, reliability, and repeatability in shade selection followed by photo colorimetric method. The Vita 3D master shows more consistent results in repetitive shade selection. Knowledge and training of the shade selection protocol are necessary for proper shade matching