Shading Model Research Articles

Modelling the Contributions of Riparian Vegetation and Topography to Stream Shade Using LiDAR and Conventional Digital Elevation Data

ABSTRACTStream temperature is widely considered the master variable in stream ecosystems. One of the key drivers of diel and seasonal stream temperature variability is the solar radiation received at the stream surface, which can be influenced by shading associated with both larger scale topographic features and riparian vegetation. In this study, a stream shade model was developed that uses LiDAR point cloud data to model shading by riparian vegetation, including canopy overhang, and conventional elevation data to model stream shading by topography. The model was applied to a dominantly north–south oriented river flowing in a floodplain within a mountain valley. When compared with shade interpreted from PlanetScope visual imagery, the model predicted stream shade at the point scale with 92% agreement. Sources of error were attributed to pixel and azimuth band size, which can be refined within the model arguments, although at the cost of increased processing time. The shade model was re‐run after virtually rotating the reach by 90° and 270° clockwise to evaluate the effect of valley orientation. Peak reach‐wide sunlight exposure occurred approximately 2 h later in the day when the stream reach was rotated 90°, and produced greater shading from mid‐morning to mid‐afternoon. Further work should test the model on smaller streams using ground‐based oblique or drone‐based photography to provide ground‐truthing, particularly to assess the accuracy of predicted shade below over‐hanging vegetation.

Kinetics model with experimental validation for optimal microalgae generation in double-skin façades

Microalgae photobioreactors integrated into double-skin façades in cold climates enhance growth conditions for biomass generation, CO2 fixation, and O2 production, while reducing thermal loads. However, shading imposed by double-skin façade's assembly limits light interception for the photobioreactors. This study employs kinetics and shading models to estimate variations in biomass concentration within the light-constrained photobioreactor. To validate the accuracy and reliability of the model, the results were compared to experimental data collected by the authors from a full-scale constructed system. Biomass concentration was monitored using a developed RGB image-based monitoring technique. Direct search methods were employed to optimize the design and operational variables of the microalgae photobioreactors, with the goal of maximizing annual areal and volumetric productivities across 14 Canadian cities under various climatic conditions. Hooke-Jeeves algorithm was 65.6 % faster than Powell's conjugate direction method. This showed the system's adaptability by generating 1.3–3.0 kg/m2.year of biomass in different climates. The study established a framework for optimizing microalgae photobioreactors into façades to maximize biomass harvest.

Neural Appearance Model for Cloth Rendering

AbstractThe realistic rendering of woven and knitted fabrics has posed significant challenges throughout many years. Previously, fiber‐based micro‐appearance models have achieved considerable success in attaining high levels of realism. However, rendering such models remains complex due to the intricate internal scatterings of hundreds of fibers within a yarn, requiring vast amounts of memory and time to render. In this paper, we introduce a new framework to capture aggregated appearance by tracing many light paths through the underlying fiber geometry. We then employ lightweight neural networks to accurately model the aggregated BSDF, which allows for the precise modeling of a diverse array of materials while offering substantial improvements in speed and reductions in memory. Furthermore, we introduce a novel importance sampling scheme to further speed up the rate of convergence. We validate the efficacy and versatility of our framework through comparisons with preceding fiber‐based shading models as well as the most recent yarn‐based model.

From Dawn to Dusk: High-Resolution Tree Shading Model Based on Terrestrial LiDAR Data

Light availability and distribution play an important role in every ecosystem as these affect a variety of ecosystem processes and functions. To estimate light availability and distribution, light simulations can be used. Many previous models were based on highly simplified tree models and geometrical assumptions about tree form, or were sophisticated and computationally demanding models based on 3D data which had to be acquired in every season to be simulated. The aim of this study was to model the shadow cast by individual trees at high spatial and temporal resolution without the need for repeated data collection during multiple seasons. For our approach, we captured trees under leaf-off conditions using terrestrial laser scanning and simulated leaf-on conditions for individual trees over the remainder of the year. The model was validated against light measurements (n=20,436) collected using 60 quantum sensors underneath an apple tree (Malus domestica Borkh.) on a sunny and cloudless summer day. On this day, the leaves and the shadow were simulated with a high spatial (1 cm) and temporal resolution (1 min). The simulated values were highly correlated with the measured radiation at r=0.84. Additionally, we simulated the radiation for a whole year for the sample apple tree (tree height: 6.6 m, crown width: 7.6 m) with a resolution of 10 cm and a temporal resolution of 10 min. Below the tree, an area of 49.55 m² is exposed to a radiation reduction of at least 10%, 17.74 m² to at least 20% and only 0.12 m² to at least 30%. The model could be further improved by incorporating branch growth, curved leaf surfaces, and gravity to take the weight of the foliage into account. The presented approach offers a high potential for modelling the light availability in the surroundings of trees with an unprecedented spatial and temporal resolution.

A comprehensive review of urban growth studies and predictions using the Sleuth model

Urban growth is a complex phenomenon It has been the subject of in-depth research for the last few years. There are various models used to measure and simulate urban growth. Most of these methods are founded on GIS & RS techniques coupled with the CA algorithm, as only these tools and techniques have the capabilities to conduct spatiotemporal studies, manage spatiotemporal dynamics, and provide a detailed depiction and modeling from the bottom-up tactic. Recently, the slope, land use, exclusion, urbanization, transportation, and hill shade (SLEUTH) model has been the most commonly used model. It is easily accessible because it is open source; moreover, its source code is also easily accessible. The SLEUTH model’s name alludes to the necessary inputs —slope, land use, excluded area, urban extension, transportation, network and hillshade. The model has been used in many cities and has proven to be efficient. The present review paper reviews the past literature pertaining to urban development and prediction to further support the research on urban planning, urban growth and prediction.

Development of a heat load index and risk map for grazing sheep

ABSTRACT A total of 5500 measurements of the respiration rate of 123 sheep with and without access to shade were obtained on 40 days in the summers (January–April) of 2022(Year 1) and 2023(Year 2). Models to predict respiration rate (breaths per minute (BPM)) based on temperature, humidity, wind speed, and solar radiation were calibrated to the Year 1 unshaded dataset (R2 =0.35, RMSE=39 BPM) and validated with the Year 2 unshaded dataset (R2=0.58, RMSE=40 BPM). Respiration rate increased 6 BPM for each 1°C increase in temperature. The shade treatment decreased respiration rate by 24 BPM and the shaded model for respiration rate had a validation RMSE of 47 BPM. The between sheep variability in respiration rate was described by a standard deviation of 18.9 BPM. The probability of open mouth and tongue out behaviours both increased linearly from 200 BPM. We constructed a daily Heat Load Index based on the cumulative respiration rate greater than 200 BPM. Climate data and sheep density information were used to construct a heat stress risk map for New Zealand from October 2018 to March 2022. Heat stress risk was concentrated in January–February and was primarily located on the east coast of the North Island.

Optimization Control Strategy for Transition Season Blinds Balancing Daylighting, Thermal Discomfort, and Energy Efficiency

Natural lighting in office buildings is often affected by excessive solar heat gain and discomfort glare, and the transitional seasons are no exception. Therefore, addressing the issue of natural lighting in buildings has always been a challenge in developing shading control strategies. This study designed a model-based calculation method for shading blind control indicators. The method combines existing physical models for sky conditions, solar radiation, heat transfer, thermal comfort, glare, and illuminance calculations and incorporates modifications and additions. Additionally, an equivalent energy-saving model for shading was established. A shading blind control strategy balancing indoor light and the thermal environment with energy savings during transitional seasons was proposed. In transitional seasons, this method can eliminate 100% of glare, reduce discomfort illuminance duration by 81.3% and heat discomfort duration by 87.5% and save 81.3% of lighting energy consumption when air conditioning is used. By comparing the simulation results of an office building in Xi’an with the results obtained from this calculation method, the absolute error percentage was found to be 6.83%, verifying the reliability of the calculation method. Finally, the proposed control strategy was compared with common methods such as no blinds, end-angle control, and fixed-angle control to evaluate its performance in terms of daylighting, thermal comfort, and energy savings. The results showed that the control strategy proposed in this study has significant advantages with respect to various performance indicators.

Real-time Realistic Volume Rendering of Consistently High Quality with Dynamic Illumination.

Direct Volume Rendering (DVR) plays an important role in scientific data visualization. To generate photo-realistic DVR results, the physical light transport throughout the volume is simulated by applying the Monte Carlo-based volumetric path tracing (VPT) approach. For real-time applications, due to the time constraint for rendering each frame, only a limited number of samples shall be taken for the computation per pixel. This can result in a significant amount of noise in the rendering results. This paper describes our optimized VPT sampling algorithm and a novel denoising technique to generate consistently high-quality realistic DVR results in real time. We develop a new shading model that can reduce estimation variance to enhance the quality of DVR results. Additionally, a hybrid acceleration structure is created by integrating both octree and macrocell to improve sampling efficiency. This allows the acquisition of sufficiently more shading samples while maintaining the desired interactive frame rate. To further eliminate remaining noise and improve temporal stability of DVR results, we develop a novel spatiotemporal denoising framework. Our denoiser decouples the estimated radiance into high-detail low-noise and low-detail high-noise components. Different denoising algorithms are separately applied to these components to reduce noise without introducing blurring artifacts. Our DVR system can consistently offer high rendering quality and good temporal stability across DVR result frames in real time. During fast user interactions and with rapid alterations of the illumination condition, our rendering method can still provide good visual comfort and representation accuracy without visible latency.

Shading in Utility‐Scale Photovoltaic Plants: A Hemicube Approach for Efficient Shading Calculations

Accurate estimations of energy production in the planning and design stage of photovoltaic (PV) plants require advanced and efficient models to simulate shading effects. This is particularly important for plants located in complex terrain or plants that are affected by nearby shading obstacles. Herein, a hemicube approach is presented for calculating shading effects and assessing the model accuracy and performance for utility‐scale PV plants. The proposed model is thoroughly illustrated for common direct beam and diffuse irradiance shading effects occurring in solar plants. The article illustrates how the accuracy and computing needs of the model can be affected by the tuning of key parameters using as case studies several PV plants from 1 to 100 MW and different ground coverage ratios. The model is validated in a 16 MW PV plant located in a complex terrain. Finally, the results demonstrate how the proposed hemicube model can be set to leverage accurate and efficient computing performance. The proposed hemicube‐based shading model has been implemented in SolarFarmer, a commercial PV design software, to facilitate the PV industry, produce accurate energy yield assessments, and support the ongoing clean energy transition.

Effects of Luminance Contrast on Depth Perception in Optical See-Through Augmented Reality

ABSTRACT Augmented reality (AR) technology presents the rendered virtual object in the real world whose depth cues can assist the depth estimation of the virtual object. For many AR applications, the successful interaction between the real world and the virtual object relies on the accuracy of depth perception. In the past, the research of depth perception in AR mainly focused on the impact of virtual object properties, including the size, color, and shading model. In this study, an experiment has been conducted to investigate the influence of ambient luminance, virtual object luminance, and shading model which is a luminance-related parameter on depth perception using an optical see-through head-mounted display. Results show that a higher luminance contrast between the real scene and the virtual object leads to a lower accuracy of depth perception in AR.

A Practical and Hierarchical Yarn‐based Shading Model for Cloth

AbstractRealistic cloth rendering is a longstanding challenge in computer graphics due to the intricate geometry and hierarchical structure of cloth: Fibers form plies which in turn are combined into yarns which then are woven or knitted into fabrics. Previous fiber‐based models have achieved high‐quality close‐up rendering, but they suffer from high computational cost, which limits their practicality. In this paper, we propose a novel hierarchical model that analytically aggregates light simulation on the fiber level by building on dual‐scattering theory. Based on this, we can perform an efficient simulation of ply and yarn shading. Compared to previous methods, our approach is faster and uses less memory while preserving a similar accuracy. We demonstrate both through comparison with existing fiber‐based shading models. Our yarn shading model can be applied to curves or surfaces, making it highly versatile for cloth shading. This duality paired with its simplicity and flexibility makes the model particularly useful for film and games production.

Optimized topology for a photovoltaic array using switches control

The photovoltaic (PV) industry is experiencing rapid growth driven primarily by rising global energy demand and the inevitable transition to sustainable energy sources. Nevertheless, various factors impede the performance of PV panels, prompting researchers to consider novel PV systems. Mismatch loss is a significant concern induced by dust accumulation, nearby objects, or bird droppings, which restrict the power output of the PV array, particularly when interconnected in the standard mode. In this context, the present investigation aimed to identify the optimal topology for different partial-shading models. The proposed approach automatically manipulates switches to ensure an appropriate interconnection scheme by utilizing a novel process based on the perturb and observe (P&O) concept. Furthermore, this study applies advanced global maximum power point tracking (GMPPT) techniques based on PV curve scanning and the enhanced P&O method to effectively manage the PV system’s maximum power output during dynamic partial shading conditions (PSC). The power–voltage (P–V) curves and power production associated with each shading model are analyzed using MATLAB Simulink to assess the validity and effectiveness of the approach. Ultimately, the methodology achieves a special power rate exceeding 20 W for a small-scale PV plant with a capacity of 240 W under certain shading patterns, notably random shading distribution.

Combined volume and surface rendering with global illumination caching

We present a combined volume and surface rendering technique with global illumination caching. Our approach uses volumetric path tracing to compute the global illumination volume and local shading models for rendering the isosurface. By joining both visualization approaches, we have enhanced the display and illumination of the surfaces while preserving physically realistic illumination of the participating media. To achieve real-time performance and avoid recomputing the image when the camera view changes, we compute the global illumination volume incrementally and defer the projection to a later step. We evaluated our technique by comparing different local shading models for isosurface rendering with the result of full volumetric path tracing and with the non-caching variant of our technique. Results show that the caching and non-caching variants perform comparably well, while the caching variant has the added benefit of being camera-view-independent. Additionally, we show that our approach emphasizes the surfaces within volumes better than volumetric path tracing.

Impact of shading on evapotranspiration and water stress of urban trees

AbstractEvapotranspiration of urban street trees is essential in mitigating urban heat islands due to its cooling effect. However, current shifts in rainfall and temperature regimes towards drier and hotter periods in Central Europe have caused substantial water stress for street trees. Quantifying and subsequently managing these changing dynamics as well as estimating evapotranspiration and water availability is necessary but at the same time extremely challenging in urban environments. Both dynamics are influenced by soil sealing and complex shading patterns of the surrounding street canyon, which vary on a small spatial scale as a function of the canyon layout and orientation. In the present study, the diurnal patterns of six typical urban shading types for street trees were derived by considering a large set of street orientations, widths and tree positions within the street canyon. A shading model was integrated into a hydrological urban tree model to assess the impact of those shading types on diurnal patterns of radiation and evapotranspiration rates calculated using the Penman–Monteith approach and the resulting soil moisture conditions for several vegetation seasons and water‐supply scenarios. The modelling results showed that the six shading patterns significantly influenced the simulated hourly, daily and seasonal potential and actual evapotranspiration rates and water availability. Shaded trees have a substantially reduced, simulated water stress period, regardless of initial water supply, and are able to provide a longer‐lasting cooling function during dry periods due to higher evapotranspiration rates later in the summer season.

A new trigonometric model for solar radiation and shading factor: Varying profiles of building façades and urban eccentricities

Solar energy utilizations in buildings are contingent on efficient shading models. This paper presents a new trigonometric model that was simple in application and robust in handling diverse site environments. The developed model was experimentally validated and compared to existing shading techniques such as pixel counting and polygon clipping. Additional analyses were performed to examine building façades ranging from flat to free-form surfaces in both linear and non-linear urban forms. This study integrated two submodels into the shading model to estimate the reduction in cooling demand and the energy production from solar applications. On annual basis, elliptical urban grids provided less normal beam radiation by a mean of 4.7 % or 22.8 W/m2 than the linear grids tangent to the curvilinear ones. South-facing façades gained more radiation by a factor ranging from 1.26 to 1.55 due to wider street grid conditions. Shade-less protrusions of the free-form façades allowed the incidence factor to reach up to 0.91 compared to 0.35 in flat façades. Although the developed model had an average error of 5.2 %, the computational time was reduced by more than 40 %.

Wavefront recording plane-like method for polygon-based holograms.

The wavefront recording plane (WRP) method is an algorithm for computer-generated holograms, which has significantly promoted the accelerated computation of point-based holograms. Similarly, in this paper, we propose a WRP-like method for polygon-based holograms. A WRP is placed near the object, and the diffracted fields of all polygons are aggregated in the WRP so that the fields propagating from the polygonal mesh affect only a small region of the plane rather than the full region. Unlike the conventional WRP method used in point-based holograms, the proposed WRP-like method utilizes sparse sampling in the frequency domain to significantly reduce the practical computational kernel size. The proposed WRP-like method and the analytical shading model are used to generate polygon-based holograms of multiple three-dimensional (3D) objects, which are then reproduced to confirm 3D perception. The results indicate that the proposed WRP-like method based on an analytical algorithm is hundreds of times faster than the reference full region sampling case; a hologram with tens of thousands of triangles can be computed in seconds even on a CPU, whereas previous methods required a graphics processing unit to achieve these speeds.

Exploring the cooling effect of shading for climate change adaptation in coffee areas

Rising air temperatures are the main reason for the expected reduction in land suitability for coffee cultivation under climate change in Central America. One of the reasons farmers use shade trees is to create a cooler microclimate in coffee plantations located in warming areas; therefore, adjusting the shade levels could alleviate future high temperatures. Even though data on expected climatic changes are available, no studies have addressed the cooling potential of shading in coffee production systems. In this study, we use regional climate information (RCP 4.5) and a simple shade model to explore the potential of shading as an adaptation practice in the coffee areas in Central America. A model was developed to estimate the required shade levels for Coffea arabica L. based on mean air temperature. Modeled and observed shade data were compared. Results indicate that compared to 2000, an overall increment of 23 ± 18% of shading would be required to alleviate the warming conditions by 2050. The shading will be more beneficial to coffee areas at medium and high altitudes than to areas at low ones. Also, the number of coffee areas that require dense shade levels (shading > 60%) may double by 2050. This would lead to a boost in tree biomass (carbon content) but also increase the competition for the coffee plants and consequently affect coffee yields. Trade-offs between adaptation, mitigation, and productivity objectives are expected in the coffee areas in the future.

A novel approach to account for shape-morphing and kinetic shading systems in building energy performance simulations

This paper proposes an innovative approach to analyse the energy behaviour of complex kinetic shading systems. Although several studies have analysed this topic, many are focused only on certain aspects or on simple shading systems due to a lack of tools for running reliable energy simulations on complex systems. This study aims to develop and validate a tool based on Python and EnergyPlus that can consider the continuous nature of the energy simulation and analyse complex kinetic systems. Simply providing an EnergyPlus model and a model of the shading configurations, the algorithm provides as output a comparison sheet to evaluate the performance of the system. The paper provides a description of the tools and studies focused on this topic; subsequently, a methodological insight is presented to explain the workflow, its validation, and the algorithm developed. Finally, the algorithm is tested on a case study to analyse a kinetic shading system. Abbreviations: DSF: Dynamic Shading File; EDSM: Equivalent Dynamic Shading Model; EMS: Energy Management System; ESSM: Equivalent Static Shading Model; Gf: Incident irradiance; Gf max: Incident irradiance threshold; PV: Photovoltaic; ST1/2/3: State 1/2/3; SSM: Static Shading Model; SF: Sunlit Fraction; SSF: Static Shading File; To: Outdoor temperature; To max 1/2: Outdoor temperature threshold 1/2; Tsol: Solar transmittance

Fully analytic shading model with specular reflections for polygon-based hologram

For polygon-based holograms, the efficiency of the fully analytical algorithm is outstanding compared with that of the spectral interpolation-based method. However, the full analytical algorithm is not beneficial for the rendering of objects, owing to the uniform amplitude of each triangle. In this paper, we propose a shading rendering method based on a fully analytical spectrum. We used the Blinn-Phong reflection model to simulate a scene with realistic lighting and render a glossy, smooth object surface without changing the number of polygons sampled. The proposed method develops approximate exponential functions to replace cumbersome diffuse and specular reflections, allowing us to derive fully analytical spectra. The computational results for several 3D objects show that the proposed method is highly efficient and presents realistic illumination effects owing to the analytical equations.

Drawing Illustration Using Android Studio

This building is implemented with Android and machine learning in mind. We can doodle or sketch on our phones. Change a pixel at a nice spot. In this project, the programme has a variety of specialised brushes and brush sets to help you with your illustration, and it is fully customisable, allowing users to design their own brushes. Choose a shading utilizing various shading models, e.g., RGB, HSV, or by utilizing a shading eye dropper. Also, color pallet generator victimization machine learning makes it simple to form a color palette from any image, therefore it will come back the color palette as the second array of colors. Which follows the k- mean bunch algorithmic program? Keywords: Drawing App, canvas, Android App, colors