138 research outputs found
Computational Combination of the Optical Properties of Fenestration Layers at High Directional Resolution
Get PDFComplex fenestration systems typically comprise co-planar, clear and scattering layers. As there are many ways to combine layers in fenestration systems, a common approach in building simulation is to store optical properties separate for each layer. System properties are then computed employing a fast matrix formalism, often based on a directional basis devised by JHKlems comprising 145 incident and 145 outgoing directions. While this low directional resolution is found sufficient to predict illuminance and solar gains, it is too coarse to replicate the effects of directionality in the generation of imagery. For increased accuracy, a modification of the matrix formalism is proposed. The tensor-tree format of RADIANCE, employing an algorithm subdividing the hemisphere at variable resolutions, replaces the directional basis. The utilization of the tensor-tree with interfaces to simulation software allows sharing and re-use of data. The light scattering properties of two exemplary fenestration systems as computed employing the matrix formalism at variable resolution show good accordance with the results of ray-tracing. Computation times are reduced to 0.4% to 2.5% compared to ray-tracing through co-planar layers. Imagery computed employing the method illustrates the effect of directional resolution. The method is supposed to foster research in the field of daylighting, as well as applications in planning and design
Characterization and data-driven modeling of a retro-reflective coating in Radiance
No full textRetro-reflective coatings applied to blinds of reduced geometric complexity promise to provide view to the outside while effectively controlling solar gains and glare. To characterize the reflection characteristics of such coatings over the entire solar spectrum, a novel extension to a scanning gonio-photometer is developed. The extended instrument is tested and applied to measure a coating's Bidirectional Reflection Distribution Function including the region of the retro-reflected peak. The measured data-sets are compiled into a data-driven reflection model for the daylight simulation software Radiance. This model is applied to illustrate the coating's effect in a comparison to purely diffuse and specular surface finishes on geometrically identical, flat blinds. Daylight supply, the probability of glare, and solar gains are assessed for an exemplary, South-oriented office under sunny sky conditions. The results indicate the potential of the coating to effectively shade direct sun-light even if applied on blinds with minimalistic geometries. The modeling technique is shown to be a general means to replicate the irregular optical properties of the coating, which cannot be represented by the standard models in daylight simulation software.+ ID der Publikation: hslu_49059 + Art des Beitrages: Wissenschaftliche Medien + Sprache: Englisch + Letzte Aktualisierung: 2018-02-09 16:47:2
Photon mapping to accelerate daylight simulation with high-resolution, data-driven fenestration models
Get PDFCISBAT 2019: Climate Resilient Cities – Energy Efficiency & Renewables in the Digital Era
4–6 September 2019, EPFL Lausanne, SwitzerlandData-driven modelling provides a general means to represent optically complex fenestration in daylight simulation by its Bidirectional Scattering Distribution Function (BSDF). Radiance employs the tensor tree as a compact data structure to store the BSDF at high directional resolution. The application of such models under sunny sky conditions is, however, computationally demanding, since the density of stochastic backward samples must match the BSDF resolution. The bidirectional Photon Map is proposed to rapidly forward-sample the BSDF, starting from the known sun direction. Its exemplary application shows a potential speed-up of ≥ 98% when compared to backward ray-tracing
Measured BSDF and data-driven model of a laser cut panel (LCP001)
No full text<p>Model generated from the measured Bidirectional Scattering Distribution Function (BSDF) of a LCP. The RADIANCE tool-chain pabopto2bsdf, bsdf2ttree was employed. Initial tensor resolution set to 128x128 incident, and equal number of outgoing, scattered directions (corresponding to approx. 1.4 degree). Subsequent adaptive data reduction by approx. 98%. Photometric BSDF.</p>
<p>The measured data is included as Differential Scattering Function (DSF): DSF = BSDF x cos(theta_s), where theta_s is the off-normal angle of the outgoing, scattered direction of light (the first column in the measured data). The data was measured on a scanning gonio-photometer (pab advanced technologies pgII) at the optical laboratory of CC Building Envelopes. A halogen lamp was employed, focud on the detector plane for maximum resolution, with a hot-mirror installed in the illuminator to block near infrared emission. The Si photocell of the detector was equipped with a weighing filter to match photometric response v(lambda). The profiles through the unobstructed beam are given for the phi=0°,180°, and phi=90°,270° planes.</p>
<p>The angular coordinates theta=90, phi=0 correspond to the intended up direction when installed vertically, e.g. in a window.</p>
<p>When publishing any work making use of this data-set, please reference either this data-set, including its Digital Object Identifier (DOI:<a href="https://doi.org/10.5281/zenodo.3375294">10.5281/zenodo.3375294</a>), or (preferred) by this article which describes sample, model and its exemplary application:</p>
<p>Lars Oliver Grobe. Photon mapping in image-based visual comfort assessments with BSDF models of high resolution. Journal of Building Performance Simulation. DOI:10.1080/19401493.2019.1653994</p>This research was financially supported by the Swiss Innovation Agency
Innosuisse and is part of the Swiss Competence Center for Energy Research
SCCER FEEB&D
High-resolution data-driven models of daylight redirection components
Get PDFDaylight Redirecting Components (DRCs) guide daylight to zones with insufficientdaylight exposure. They reduce energy demand for lighting, heating and cooling, and improve visual and thermal comfort. The data-driven model in Radiance is a general means to model DRCs in daylight simulation. Rather than internal opticalmechanisms, their resulting Bidirectional Scattering Distribution Function (BSDF) isreplicated. We present models of two DRCs that are generated from measurements. The impact of three necessary steps in the generation of data-driven models from measured BSDF shall be evaluated:1. interpolation between measurements at sparse sets of incident directions,2. extrapolation for directions that cannot be measured, and3. application of a directional basis of given directional resolution.
It is shown that data-driven models can provide a realistic representation of both DRCs. The sensitivity to effects from interpolation differ for the two DRCs due to the different complexity of their BSDFs. Due to the irregularity of the measured BSDFs, extrapolation is not reliable and fails for both tested DRCs. Different measurement and modeling protocols should be applied to different classes systems, rather than aiming at a common low-resolution discretization.+ ID der Publikation: hslu_47609 + Art des Beitrages: Wissenschaftliche Medien + Jahrgang: 5 + Sprache: Englisch + Letzte Aktualisierung: 2017-10-04 13:37:5
Light Scattering by Roman window glass
No full textThis archive contains data-sets representing the light scattering properties of four samples of Roman window glass, as described in detail in Grobe, Noback, and Lang. Data-Driven Modelling of Daylight Scattering by Roman Window Glass. ACM Journal on Computing and Cultural Heritage (manuscript accepted with minor revisions). For each sample, a sub-directory contains the measured DSF (BSDF x cos theta) and a transmission and reflection model for use with the light simulation software Radiance.
Each directory contains metadata in Dublin Core and Marc21 format, giving detailed information about the individual dataset.</p
Scale-Model And Simulation-Based Assessments For Design Alternatives Of Daylight Redirecting Systems In A Side-Lighting Educational Room
Get PDFDaylight has been proven to have positive effects on well-being, comfort
and performance of occupants in buildings; it specifically increases learning
performance in educational buildings. Side-lighting from one direction
leads to unbalanced and insufficient illuminance, especially in large and
deep spaces. A design studio at the Izmir Institute of Technology (IZTECH)
in Urla, Turkey, has been chosen as an example of a space in such a context.
Its geometrical attributes has taken to be the baseline. First, four daylight
redirecting systems are applied on its 1/15 scale model to understand and
compare their redirection behavior visually. Second, measurements on the
scale model are taken to compare the daylight illuminance distributions.
Third, to assess the overall performance in the sunny climate, illuminance
and luminance maps for photorealistic visualization are calculated in
monthly steps over one year. For efficient calculation of the time-steps to
be considered, the daylight coefficient method has been applied. Though
light ducts are found to be effective for high sun angles, in summer and
equinoxes; very low illuminance in entire space make them fail in winter.
Light shelves are determined to be the most convenient ones for this space,
since they provided sufficient, uniform and high illuminance in equinoxes
and winter.Gün ışığının, bina kullanıcılarının refahı, konforu ve performansı
üzerinde pozitif etkisi olduğu kanıtlanmıştır. Günışığı, özellikle, eğitim
yapılarında öğrenme performansını da artıran bir etmendir. Tek yönlü
yan aydınlatma, özellikle geniş ve derin hacimlerde, aydınlık düzeyinin
dengesiz ve yetersiz olmasına yol açar. Bu bağlamda, İzmir Yüksek
Teknoloji Enstitüsü (İYTE)’nde (Urla-Türkiye) bir tasarım stüdyosu, örnek
olarak seçilmiştir. Geometrik özellikleri temel alınmıştır. İlk olarak, dört
farklı ışık yönlendirme sistemi, ışık yönlendirme davranışlarının görsel
olarak anlaşılması ve birbirleriyle karşılaştırılması için, 1/15 ölçekli makette
uygulanmıştır. İkinci olarak, günışığı aydınlık düzeyi dağılımlarını
karşılaştırabilmek için makette ölçümler yapılmıştır. Üçüncü olarak,
performansın güneşli bir iklimde değerlendirilmesi amacıyla, aydınlık
düzeyi ve fotogerçekçi görselleştirme adına parıltı dağılımları, tüm yıl
boyunca aylık olarak hesaplanmıştır. Verimliliklerin istenilen zamanlarda
hesaplanabilmesi için günışığı katsayısı yöntemi uygulanmıştır. Güneş açılarının yüksek olduğu durumlar için ışık bacalarının daha etkin olduğu
bulunmuş; buna karşın, kışın tüm hacimdeki aydınlık düzeyi çok düşük
olduğundan bu sistemler başarısız olmuştur. Işık rafları ise bu hacim için
en uygun sistem olarak belirlenmiştir; çünkü bu sistemler, ekinoks ve yaz
dönemlerinde aydınlık düzeyini yeterli bir şekilde, düzgün dağılımlı ve
yüksek olarak sağlamıştır
Photon Mapping in Image-Based Visual Comfort Assessments With Bsdf Models of High Resolution
No full textData-driven models replicate the irregular Bidirectional Scattering Distribution Functions (BSDFs) of optically Complex Fenestration Systems in daylight simulation. RADIANCE employs the tensor tree to store the BSDF at high directional resolution. Its application in backward ray-tracing is however challenging, since the density of stochastic samples must match the model resolution. BSDF proxy and peak extraction address this problem, but are limited to cases when either the fenestration geometry, or the shape and direction of the transmission peak are known. Photon Mapping is proposed to efficiently sample arbitrary BSDFs from the known sun direction. The existing implementation in RADIANCE is extended to account for light sources and their reflections in the field of view, that are of particular importance for visual comfort assessments. The method achieves a high degree of accordance with ray-tracing, and reduces simulation times by approximate to 95% with data-driven models of high resolution
Günışığı yönlendirmeli pencerenin değişken yönlü çözünürlükte veri dayalı modellenmesi
No full textThesis (Doctoral)--Izmir Institute of Technology, Architecture, Izmir, 2019Includes bibliographical references (leaves: 150-161)Text in English; Abstract: Turkish and EnglishDaylight Redirecting Fenestration (DRF) aims at the optimal utilisation of daylight in buildings striving for high visual comfort standards. Daylight simulation allows to assess whether this objective is met in architectural context, and guides decisions in building design as well as the development of DRF. The
daylight simulation suite Radiance allows to employ data-driven models of variable resolution to accurately replicate the irregular light scattering by DRF. In this context, this research provides methods to improve DRFs’ integration in daylight assessments. The thesis consolidates a series of publications that
address particular problems in the generation and application of data-driven models, with a focus on accurate image synthesis for visual comfort assessments. First, the parametrisation of model generation from gonio-photometric measurements is tested. Second, a novel extension of the instrumentation allows to characterise and subsequently model retro-reflection by an innovative coating. Applied in DRF, the coating controls solar gains and glare, while maintaining a view to the outside. Third, to assemble accurate data-driven models of fenestration layers into descriptions of the entire DRF, an approach employing matrix calculations is adapted and tested. Finally, the Photon Map implementation in Radiance is modified for efficient image synthesis with data-driven models, and employed in a simplified but accurate approach to Climate-Based Daylight Modelling that demonstrates the potential of retro-reflection to efficiently control glare and maintain view with static DRF. The research contributes to the applicability of data-driven models, and confirms the potential of DRF to reconcile diverging daylight performance
targets such as glare control and view.Günışığı Yönlendirmeli Pencere (GYP), yüksek görsel konfor standartlarını
sağlamak için çaba sarfeden binalarda günışığının en iyi şekilde kullanılmasını
amaçlar. Günışığı benzetimi mimari bağlamda bu hedefin sağlanıp sağlanmadığının
değerlendirilmesine imkan tanır. Bina tasarımında ve aynı zamanda
GYP’lerin geliştirilmesinde alınacak kararları yönlendirir. Böyle bir benzetim
aracı olan Radiance, GYP’nin düzensiz optik özelliklerini tekrarlayarak
değişken yönlü çözünürlükte veri dayalı modeler kullanabilir.
Bu tez, bu bağlamda, GYP’lerin doğal aydınlatma analizine katılmasını
geliştirmek için yeni bir yöntem önermektedir. Metin, görsel konfor değerlendirmelerinde,
özellikle görüntülerin doğru sentezlenmesine odaklanarak, veri
dayalı modellerin oluşturulması ve uygulanması hakkındaki problemleri işaret
eden makaleleri birleştirmektedir. İlk olarak, gonio-fotometrik ölçümlerden oluşturulan
parametrik model test edilmektedir. İkinci olarak, bu ölçüm cihazına yeni
bir eklenti ile yeni bir kaplamanın geri yansıtma özelliklerinin modellenmesi ve
karakterizasiyonu sağlanır. GYP’lere uygulanan bu kaplama, dışarıya olan görüşü
koruyarak ısı kazançlarını ve kamaşmayı kontrol eder. Üçüncü olarak, pencere
katmanlarının değişken yönlü çözünürlükte modellerinin kombine edilmesi için
matris hesaplamaları uyarlayan bir yaklaşım oluşturulup test edilmiştir. Sonra,
Radiance programına katılan Photon Map uygulaması, veri dayalı modeller
ile etkin bir görsel sentez için modifiye edilip geliştirilmiştir. Photon Map
İklime Dayalı Günışığı Modellemesi yöntemini basitleştirmekte; görüşü kapatmayan
ve görsel konforu artıran statik/hareket etmeyen GYP’lerin geri yansıtma
potansiyelini göstermektedir
Bu araştırma, değişken yönlü çözünürlükte, veri dayalı modellerin uygulanmasına
katkıda bulunur ve GYP’nin kamaşma kontrolü ve manzara gibi günışığı
performansı hedeflerini yakalama potansiyelini kesinleştirir
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