A practical analytic model for daylight

Preetham, Arcot J.; Shirley, Peter; Smits, Brian

doi:10.1145/311535.311545

Cited by 250 publications

(207 citation statements)

References 25 publications

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“…Later developments were focused to account for physically based coloured skylight models, that are directly useful for rendering purposes -single scattering model [116], multiple scattering model [117]. Preetham et al [118] developed a model based on the Perez All Weather model and Nishita model, that analytically solve sky luminance distribution. This model currently represents the de facto standard analytical model of coloured skydome radiance.…”

Section: Naturalmentioning

confidence: 99%

State-of-the-art review of solar design tools and methods for assessing daylighting and solar potential for building-integrated photovoltaics

Jakica

2018

Renewable and Sustainable Energy Reviews

129

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Solar design can take many different forms across disciplines with different methodologies and goals, ranging from acquiring architectural visual effects to assessing illumination for daylighting and solar radiation potential on building surfaces for PV implementation. Furthermore, a capability of solar design methodologies and tools to accurately and time efficiently simulate light phenomena can greatly influence performance results and design decisions. This is especially important in complex cases such as dense urban settings with the significant surface shadowing, and vertical facades including daylighting devices and photovoltaics. Consequently, choosing a suitable approach and tool for each design phase is essential for achieving unique design and performance goals. This paper was carried out within the framework of IEA-PVPS Task 15 -BIPV and it aims to facilitate this decision for all parties involved in solar design process. Here presented, is an overview of almost 200 solar design tools, analyzing their numerous features regarding accuracy, complexity, scale, computation speed, representation as well as building design process integration in about 50 2D/3D, CAD/CAM and BIM software environments. Furthermore, tools from various fields have been analysed in a broad interdisciplinary context of solar design with a particular attention for being used for Daylighting and Building-Integrated Photovoltaics (BIPV) purposes. This approach should open many new perspectives on a potentially wider multidisciplinary usage and interpretation of solar design tools, sometimes well beyond their initial scope of work.

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Section: Naturalmentioning

confidence: 99%

State-of-the-art review of solar design tools and methods for assessing daylighting and solar potential for building-integrated photovoltaics

Jakica

2018

Renewable and Sustainable Energy Reviews

129

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“…As suggested in [9], those constants can also be expressed as a linear function of a single parameter, the turbidity t. Intuitively, the turbidity encodes the amount of scattering in the atmosphere, so the lower t, the clearer the sky. For clear skies, the constants take on the following values: a = −1, b = −0.32, c = 10, d = −3, e = 0.45, which corresponds approximately to t = 2.17.…”

Section: All-weather Perez Sky Modelmentioning

confidence: 99%

“…Using this intuition, we now consider two ways of fitting our model to skies that may contain clouds. Note that we perform all processing in the xyY color space as recommended in [9].…”

Section: Application: Separation Of Sky and Cloud Layersmentioning

confidence: 99%

“…To reduce the number of variables, we follow [9] and express the five weather coefficients as a linear function of a single value, the turbidity t. Strictly speaking, this means minimizing over…”

Section: Least-squares Fittingmentioning

confidence: 99%

“…One of the most popular physically-based sky model was introduced by Perez et al [7]. This model has been used in graphics for relighting [8] and rendering [9]. Surprisingly however, very little work has been done on extracting information from the visible sky.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

What Does the Sky Tell Us about the Camera?

Lalonde¹,

Narasimhan²,

Efros³

2008

Lecture Notes in Computer Science

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Abstract. As the main observed illuminant outdoors, the sky is a rich source of information about the scene. However, it is yet to be fully explored in computer vision because its appearance depends on the sun position, weather conditions, photometric and geometric parameters of the camera, and the location of capture. In this paper, we propose the use of a physically-based sky model to analyze the information available within the visible portion of the sky, observed over time. By fitting this model to an image sequence, we show how to extract camera parameters such as the focal length, and the zenith and azimuth angles. In short, the sky serves as a geometric calibration target. Once the camera parameters are recovered, we show how to use the same model in two applications: 1) segmentation of the sky and cloud layers, and 2) data-driven sky matching across different image sequences based on a novel similarity measure defined on sky parameters. This measure, combined with a rich appearance database, allows us to model a wide range of sky conditions.

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Remote sensing of normalized diffuse attenuation coefficient of downwelling irradiance

et al. 2016

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The diffuse attenuation of downwelling irradiance, Kd (m−1), is an important property related to light penetration and availability in aquatic ecosystems. The standard Kd(490) product (the diffuse attenuation coefficient at 490 nm) of the global oceans from satellite remote sensing has been produced with an empirical algorithm, which limits its reliability and applicability in coastal regions. More importantly, as an apparent optical property (AOP), Kd is a function of the angular distribution of the light field (e.g., solar zenith angle). The empirically derived product thus contains ambiguities when compared with in situ measurements as there is no specification regarding the corresponding solar zenith angle associated with this Kd(490) product. To overcome these shortcomings, we refined the Kd product with a product termed as the normalized diffuse attenuation coefficient (nKd, m−1), that is equivalent to the Kd in the absence of the atmosphere and with the sun at zenith. Models were developed to get nKd from both in situ measurements and ocean color remote sensing. Evaluations using field measurements indicated that the semianalytically derived nKd product will not only remove the ambiguities when comparing Kd values of different light fields but will also improve the quality of such a product, therefore maximizing the value offered by satellite ocean color remote sensing.

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A practical analytic model for daylight

Cited by 250 publications

References 25 publications

State-of-the-art review of solar design tools and methods for assessing daylighting and solar potential for building-integrated photovoltaics

State-of-the-art review of solar design tools and methods for assessing daylighting and solar potential for building-integrated photovoltaics

What Does the Sky Tell Us about the Camera?

Remote sensing of normalized diffuse attenuation coefficient of downwelling irradiance

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