RESEARCH

RESEARCH INTERESTS

RECENT RESEARCH PROJECTS:


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.

sky

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ACKNOWLEDGEMENTS:

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

NEW METRIC FOR QUANTIFYING THE DIRECTIONALITY OF LIGHT:

DIRECTIONAL - TO - DIFFUSE RATIO


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.


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EVALUATION OF HIGH DYNAMIC RANGE PHOTOGRAPHY
AS A LUMINANCE MAPPING TECHNIQUE

photosphere    false color


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.

ACKNOWLEDGEMENTS:

This work was sponsored 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.

PUBLICATIONS:

  • Inanici MN. “Evaluation of High Dynamic Range Photography as a Luminance Measurement Technique”, Journal of Lighting Research and Technology, Vol. 38, no. 2, June 2006, pp. 123-136.
  • Inanici MN . “Per-pixel Data Acquisition with High Dynamic Range Photography” International Commission on Illumination (CIE) 2005 Conference, Leon, Spain, 18-20 May, 2005.
  • Inanici MN and Galvin J. Evaluation of High Dynamic Range Photography as a Luminance Mapping Technique. Lawrence Berkeley National Laboratory, LBNL Report # 57545, 2004. Available from: University of California eScholarship Repository and LBNL Library.

APPLICATIONS:

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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 – Federal Energy Management Program (FEMP)

 

 

VIRTUAL LIGHTING LABORATORY

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.

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OTHER RECENT PUBLICATIONS: