hdr

sim

ibl

analysis

eeb

 

 

RESEARCH

Google Scholar

Research Gate

Recent Publications:

Inanici M. "Focusing on Daylight Spectra", Illuminating Engineering Society (IES), Forum for Illumination Research, Engineering, and Science (FIRES), August 2019.

Inanici M. "Tri-stimulus Color Accuracy in Image-based Sky Models: Simulating the Impact of Color Distributions throughout the Sky Dome on Daylit Interiors with Different Orientations", IBPSA 2019 Conference, Rome, Italy, September 2-4, 2019.

Liu Y, Colburn A and Inanici M. "Predicting Annual Equirectangular Panoramic Luminance Maps Using Deep Neural Networks", IBPSA 2019 Conference, Rome, Italy, September 2-4, 2019.

Jung B and Inanici M. "Measuring Circadian Lighting through High Dynamic Range Photography", Lighting Research and Technology, 51(5),742-763. Article first published online: August 10, 2018; Issue published: August 1, 2019. https://doi.org/10.1177/1477153518792597.

Liu Y, Colburn A and Inanici M. "Computing Long-term Daylighting Simulations from High Dynamic Range Imagery using Deep Neural Networks", 2018 Building Performance Analysis Conference and SimBuild, co-organized by ASHRAE and IBPSA-USA. Chicago, IL, September 26-28, 2018.

News:

Mehlika is on sabbatical between June 2019 - December 2019 and April 2020 - September 2020.

Computing Long-term Daylighting Simulations from High Dynamic Range Imagery using Deep Neural Networks (Liu Y, Colburn A and Inanici M) received the Best paper Award in the 2018 Building Performance Analysis Conference and SimBuild, co-organized by ASHRAE and IBPSA-USA.

Evaluation of High Dynamic Range Photography as a Luminance Measurement Technique (Inanici M, 2006) has been selected as one of the 25 "classic" papers in the 50th volume of journal of Lighting Research and Technology (January 2018). In their paper, Boyce (editor in chief) and Carter (immediate past chairman of LRT) has selected 25 papers that "can be regarded as classics, in the sense that they have either initiated an area of research, completed an area of research, or, when the topic is active, have been frequently cited".

 

 

 


This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders.


 

SIM
HDR
IBL

SPECTRAL SKY MODELS

SKY SPECTRA

PUBLICATIONS:

 

Spectral properties of daylight surpasses any other light source. Its dynamic intensity and spectra across the full spectrum facilitates sustainable daylighting practices, produces best color rendition, and regulates circadian rhythms in all living beings. However, simulation models do not typically include spectral variability; daylight is modelled as a uniform, equal energy white source. In this paper, tristimulus calibration procedures are utilized to create spectrally accurate High Dynamic Range (HDR) photographs. HDR photographs of skies are collected and utilized as an input to image based lighting (IBL) simulations. The impact of color variations across the sky dome and between different sky conditions are studied. Per-pixel photopic luminances, tri-stimulus chromatic distributions, Correlated Color Temperatures (CCT) and circadian luminance and illuminance values are quantified for image-based daylighting simulations, and compared with standard colorless Perez skies.


 

HDR
 

MEASURING CIRCADIAN LIGHTING WITH HIGH DYNAMIC RANGE PHOTOGRAPHY

circadian-hdr

 

PUBLICATIONS:

Jung B and Inanici M. "Measuring Circadian Lighting through High Dynamic Range Photography", Lighting Research and Technology, 51(5),742-763. Article first published online: August 10, 2018; Issue published: August 1, 2019. https://doi.org/10.1177/1477153518792597

The human ocular system functions in a dual manner. While the most well-known function is to facilitate vision, a growing body of research demonstrates its role in resetting the internal body clock to synchronize with the 24-hour daily cycle. Most research on circadian rhythms is performed in controlled laboratory environments. Little is known about the variability of circadian light within the built and natural environments. Currently, very few specialized devices measure the circadian light, and they are not accessible to many researchers and practitioners. In this paper, tristimulus colour calibration procedures for high dynamic range photography are developed to measure circadian lighting. Camera colour accuracy is evaluated through CIE trichromatic (XYZ) measurements; and the results demonstrate a strong linear relationship between the camera recordings and a scientific-grade colorimeter. Therefore, it is possible to correct for the colour aberrations and use high dynamic range photographs to measure both photopic and circadian lighting values. Spectrophotometric measurements are collected to validate the methodology. Results demonstrate that measurements from high dynamic range photographs can correspond to the physical quantity of circadian luminance with reasonable precision and repeatability. Circadian data collected in built environments can be utilized to study the impact of design decisions on human circadian entrainment and to create guidelines and metrics for designing circadian friendly environments.

 

PRESENTATIONS:

Inanici M. "Measuring and Analyzing the Circadian Light: A Discussion on Units, Metrics, and Techniques," Presentation at DIVA Day 2017,Berkeley, CA.

Jung BY, Inanici M. "Capturing the Circadian Lighting Through HDR Photography," Radiance Workshop 2017, Portland, OR.

 


 

SIM
HDR
 

COMPUTING LONG TERM LUMINANCE MAPS FROM LIMITED NUMBER OF HDR IMAGERY

PUBLICATIONS:

liu-dnn

Annual luminance maps provide meaningful evaluations for occupants’ visual comfort, preferences, and perception. However, acquiring luminance maps require labor-intensive and time-consuming simulations or impracticable long-term field measurements. This paper presents a novel method to accelerate annual luminance-based evaluations utilizing a deep neural network (DNN). From a small subset (5%) of high dynamic range (HDR) imagery, our method can predict annual panoramic luminance maps (with 360-degrees horizontal and 180-degrees vertical field of view) within an hour. Unlike the fixed camera viewpoint of perspective or fisheye projections that are commonly used in daylighting evaluations, panoramas allow full degree-of-freedom in camera roll, pitch, and yaw, thus providing a robust source of information for an occupant’s visual experience in a given environment. The DNN predicted high-quality panoramas are validated against Radiance RPICT renderings using a series of quantitative and qualitative metrics. With the developed workflow, practitioners and researchers can incorporate long-term luminance-based metrics over multiple view directions into the design and research process without the lengthy computing processes.

This paper describes the development of a novel prediction model to generate annual luminance maps of indoor space from a subset of images by using deep neural networks (DNNs). This paper describes the development of a novel prediction model to generate annual luminance maps of indoor space from a subset of images by using deep neural networks (DNNs). The results show that by only rendering 5% of annual luminance maps, the proposed DNNs model can predict the rest with comparable accuracy that closely matches those high-quality point-in-time renderings generated by Radiance (RPICT) software. This model can be applied to accelerate annual luminance-based simulations and lays the groundwork for generating annual luminance maps utilizing High Dynamic Range captures of existing environments.

 

Hagia Sophia

This paper describes the development of a technique for extrapolation of dynamic daylighting simulations from a limited number of high dynamic range photographs.  This technique allows us to photographically capture and measure per-pixel lighting quantities from existing spaces in a limited time frame; and the measured information is used to establish a statistics based daylight coefficient model for the studied scene. It negates the need to explicitly model the geometry, material and lighting properties in existing environments, as they would be required in a typical simulation and daylight coefficient computation. Statistics based daylight coefficients can be used to perform daylighting simulations under any generic, arbitrary or any physically occurring sky conditions.

 

 

PRESENTATIONS:

LINKS:

Link to relevant other research and publications: Image Based Skies / hdrscope / Hagia Sophia

 


 

SIM
HDR
IBL

COMPARISON OF SKY MODELLING PRACTICES AND SIMULATION TECHNIQUES

3-5 PHASE

 

PUBLICATIONS:

Occupant centric performance approaches in daylighting studies promote design decisions that support human visual comfort, productivity, and visual preferences, along with more conventional energy efficiency criteria. Simulating per-pixel luminance values and luminance distribution patterns for the entire scene allows us to analyze the occupant centric metrics and performance criteria. However, there are a number of different sky models, complex fenestration models, and simulation techniques that produce either conventional point in time images or annual luminance maps. This paper discusses the similarities and differences between different techniques; and a comparison analyses provides insight about their impact on occupant centric lighting measures. The comparisons for sky modeling include the conventional CIE skies (Clear, Intermediate, and Overcast), measurement based CIE models, Perez all-weather skies, and high dynamic range image based skies. The comparison of simulation techniques include point in time simulations, image based lighting simulations, and annual luminance simulations (three-phase and five-phase methods). Results demonstrate that measurement based sky models match real world conditions with reasonable proximity, and generic CIE skies consistently underestimate the indoor lighting conditions. Annual simulation methods provide a large database of temporal luminance variations, where individual instances are comparable to point in time simulations. Long term luminance simulations provide opportunities to evaluate the percentage of the year that a given luminance based criteria is met or violated.

skies

Inanici M. and Liu Y. “Robust Sky Modelling Practices in Daylighting Simulations,” Passive and Low Energy Architecture (PLEA) 2016 Conference, Los Angeles, CA, July 11-13, 2016.

The demand for more sustainable building practices prompted the use of more analytical tools in the design processes. This research addresses a need to compare various sky models used in daylighting practices. The sky models can be mathematical or image based; they can be generic or measurement based. The selection of the right model depends on the scope of the simulation. It is recommended to use generic CIE models only for basic comparisons. When generated or calibrated with diffuse and direct irradiance values, CIE, Perez, and image based sky models yield to comparable results. Image based sky models are most useful to capture the local conditions that include the complexities of clouds and solar corona, surrounding urban fabric and forestry.

LINKS:

Link to relevant other research and publications: Image Based Skies / hdrscope / HDRI / Extrapolation

 


HDR
 

HIGH DYNAMIC RANGE PHOTOGRAPHY AS A LUMINANCE MAPPING TECHNIQUE

hdr overflow

The potential, limitations, and applicability of the High Dynamic Range (HDR) photography technique is evaluated as a luminance mapping tool. Multiple exposure photographs of static scenes are taken with a  digital camera to capture the wide luminance variation within the scenes. The camera response function is computationally derived using the Photosphere software, and is used to fuse the multiple photographs into HDR images. The vignetting effect and point spread function of the camera and lens system is determined. Laboratory and field studies have shown that the pixel values in the HDR photographs can correspond to the physical quantity of luminance with reasonable precision and repeatability.

hdr1 hdr-falsecolor legend

 

PUBLICATIONS:

 

PRESENTATIONS:

 

APPLICATIONS:

nt

Daylighting the New York Times Headquarters Building

Low Glare Outdoor Luminaire: California Energy Commission’s Public Interest Energy Research (PIER) Buildings Program

New Lighting Solutions for High-Bay Spaces: High-output T5 Lamps and Luminaires- Federal Energy Management Program (FEMP) Focus, Fall 2004.

 

ACKNOWLEDGEMENTS:

"Evaluation of High Dynamic Range Photography as a Luminance Measurement Technique" was funded by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Building Technology, Building Technologies Program of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

 

LINKS:

Link to relevant other research and publications: Image Based Skies / hdrscope / Extrapolation / Hagia Sophia


 

SIM

MULTISPECTRAL LIGHTING SIMULATIONS: CALCULATION OF CIRCADIAN LIGHT

A growing body of research has shown that human ocular system functions not only to facilitate vision but to reset the circadian clock to synchronize it with the 24 hour daily cycle and/or with the local time. Lighting professionals increasingly appreciate the influence of light on human health and wellbeing. A holistic approach to design necessitates consideration for both visual and non-visual aspects of lighting. There are established methods for analyzing the luminous environment for photopic responses, but there is a need for a workflow to study and analyze the circadian light in built environments. This research addresses this need. The objective of this research is to develop a multispectral lighting simulation tool that can be used to calculate both photopic and circadian lighting values. Instead of utilizing the traditional 3 channel simulation, multi channel simulation allows the user to divide the spectra in any number of channels.

A new tool, named Lark Spectral Lighting, is developed in Grasshoper/Rhino environment, the simulation engine is Radiance; and it is provided as an open source and freely available tool. The objective is to make circadian lighting analysis more accessible to architects, lighting designers, researchers, and other interested parties.

Lark Spectral Lighting allows for simulations both in 3 and 9 channels. Along with photopic luminance and illuminance values, Circadian values can be calculated in Circadian - illuminance (Circadian-lux) and -luminance (Circadian-cd/m2) units. The spectral power distribution of light is weighted by the spectral luminous efficiency functions of the human eye V(λ) to calculate the photopic metrics. For circadian metrics, spectral power distribution of light is weighted by a spectral circadian efficiency function. There is not a standard circadian curve, yet. The circadian models adopted in Lark calculate circadian values with both Rea et al. (2005) circadian spectral sensitivity curve and Lucas et al. (2014) melanopsin spectral sensitivity curve.

blue vs red wall

PUBLICATIONS:

PRESENTATIONS:

SOFTWARE: Lark Spectral Lighting This research is done in collaboration with Marty Brennan and Ed Clark from ZGF Architects.

LarkSpectralLighting

 


 

HDR
PER-PIXEL
 

DAYLIGHTING AND ELECTRIC LIGHTING ANALYSIS OF HAGIA SOPHIA USING HIGH DYNAMIC RANGE PHOTOGRAPHY TECHNIQUE

The lighting quality in Hagia Sophia has been a topic of interest for centuries among visitors, writers, poets, and researchers. In fact, almost all literature on Hagia Sophia includes a brief statement on its daylighting and sunlighting. In these documents lighting is defined as “poetic”, “magical” and “mystical”. Yet, there were not any comprehensive quantitative studies on Hagia Sophia’s lighting. The objectives of this research is:

1) To study the interior luminance values, luminance distribution patterns and luminance ratios in Hagia Sophia under naturally occurring sky conditions(the factors that are instrumental for creating the unique luminous environment in Hagia Sophia are discussed).

2) To study the electric lighting in conjunction with the daylighting in Hagia Sophia (the impact of electric lighting on the ambient light levels and luminance distribution patterns is evaluated during daylight hours).

3) To evaluate the analysis results and to provide recommendations on the lighting scheme of Hagia Sophia (the objective is to preserve the luminous environment as close as possible to the original design, and to improve the visitor experience).

HagiaSophia HagiaSophia-fclegend

PUBLICATIONS:

 


 


SIM
HDR
PER-PIXEL

hdrscope

This paper describes the development of a new tool called hdrscope that enables users to perform qualitative and quantitative lighting analysis via per-pixel methods. Using a simulated and photographically captured lab space as a case study, per-pixel analysis methods are described, challenges associated with per-pixel lighting analysis are discussed, and hdrscope analysis techniques are demonstrated. hdrscope is intended to lower the entry barrier for lighting professionals, and to facilitate the utilization of lighting analysis in early design and development stages as well as post occupancy. It also provides a user friendly tool for lighting experts while filling in the gaps among the current lighting analysis tools.

hdrscope

PUBLICATIONS:

SOFTWARE:

LINKS:

Link to relevant other research and publications: Image Based Skies / hdrscope / Extrapolation / Hagia Sophia


 

SIM
HDR
IBL

 

DEVELOPMENT AND EVALUATION OF IMAGE BASED SKY MODELS FOR DAYLIGHTING APPLICATIONS

 

This research demonstrates the use of High Dynamic Range (HDR) fisheye images of the sky dome in lighting simulations. The objective is to improve the accuracy of simulations with site specific sky conditions. The luminance information stored at a pixel level in an HDR photograph is used to light the simulated environment through an Image Based Rendering (IBR) technique. The results show that image based sky models can provide a more accurate and efficient method for defining the sky luminance distributions and the impact of surrounding urban fabric and vegetation as compared to generic CIE sky models and explicit modeling of surrounding urban fabric and forestry.

 

ibl

 

PUBLICATIONS:

PRESENTATION:

ACKNOWLEDGEMENT:

This work was funded by the University of Washington Royalty Research Fund (2009-2010).

DATA:

HDR sky images were captured for one day in every month between December to June (winter solstice to summer solstice) at 15 minute intervals during daylight hours. The database includes images from December 28, 2009 (32 image sets), Jan 31, 2010 (38 image sets), Feb. 20, 2010 (43 image sets), March 27, 2010 (49 image sets), April 25, 2010 (48 sets), May 23 (43 image sets), and June 22 (53 image sets). The dates were chosen around the 21st of each month. Dates vary to allow capturing varying weather conditions and to avoid inclement weather (to prevent equipment damage). The database covers a wide range of possible sun angles and sky conditions for Seattle. Sample HDR images from January under overcast sky and June under partly cloudy sky taken at noon are available here. Images © Inanici, 2011.

 

LINKS:

Link to relevant other research and publications: HDRI / hdrscope / Extrapolation


SIM
PER-PIXEL

 

GlareShade: A VISUAL COMFORT BASED APPROACH TO OCCUPANT CENTRIC SHADING SYSTEMS

glareshade1glareshade2

 

This paper presents a novel method for designing of an occupant-centric shading algorithm that utilizes visual comfort metric as the form-generating criteria. Based on the premise of previous studies that demonstrate glare as the most important factor for operating shading devices, GlareShade is introduced as a simulation-based shading methodology driven by occupant’s visual comfort. GlareShade not only responds to changing outdoor conditions such as the movement of the sun and the variation of cloud cover, but it also accounts for building specific local conditions. GlareShade draws its strength and flexibility from an occupant-centric approach that is based on the visual field of view of each occupant as the occupant is performing common visual tasks in a given environment, and the developed shading system is linked to a distributed sensing network of multiple occupants. ShadeFan is demonstrated as a proof-of-concept dynamic shading system utilizing the GlareShade method.

 


HDR
PER-PIXEL
 

LUMINANCE DISTRIBUTION PATTERNS AND GLARE: HUMAN VISUAL COMFORT METRICS

human factors

LINKS:

Link to relevant other research and publications: HDRI / hdrscope / Per-Pixel


SIM
   

LUMINANCE CONTRAST AS A DEPTH CUE

cue

 

PUBLICATIONS:


PER-PIXEL

PER-PIXEL LIGHTING DATA ANALYSIS

 

PUBLICATIONS:

LINKS:

Link to relevant other research and publications: Image Based Skies / hdrscope / HDRI / VLL

 

 


SIM
   

NEW METRIC FOR QUANTIFYING THE DIRECTIONALITY OF LIGHT:

DIRECTIONAL - TO - DIFFUSE RATIO

venus

Directionality of light is the balance between the diffuse and directional components within an environment. It has a significant impact on the appearance of 3D objects; and the visual performance and comfort of occupants within that environment. Poor directionality may produce harsh shadows on the task, cause veiling reflections towards the viewing angle, or create a dull environment. Adequate directionality may model 3D surfaces, reveal the surface textures or details of a task, and create an aesthetically pleasing environment.

A new metric is derived from the basic definition of directionality: The diffuse and directional components of the luminous environment are isolated as a unique feature of simulation-based approach and the ratio of the directional-to-diffuse light is calculated. The rationale and methodology of the directional-to-diffuse ratio is discussed through visual demonstrations and quantified metrics.

directionality

.

PUBLICATION:


SIM
   

VIRTUAL LIGHTING LABORATORY

VLL

Virtual Lighting Laboratory (VLL) is an advanced lighting analysis tool and methodology that is based on post-processing of the physically-based renderings. It enhances the integration of the lighting analysis into the architectural design process through computational tools that make the analysis more convenient, accessible, accurate, and rigorous. The research includes the theory, implementation, and application of the virtual meters (luminance meter, illuminance meter, contrast meter, integrating sphere, and colorimeter) as well as the development of unique analysis options and metrics that are pertinent to the computational per-pixel data.

 

PUBLICATIONS:

PRESENTATION:

 

VLL2

LINKS:

Link to relevant other research and publications: Per-Pixel / hdrscope / HDRI

 


EEB
   

ENERGY EFFICIENT BUILDING DESIGN

PUBLICATIONS:

 

 

Back to main page

 

© Mehlika Inanici
Last update: August 2019