Determination of daylight conditions in office room using digital images as a light source.

Abstract

The paper presents comparative analysis of daylight conditions in office room simulated with two techniques of sky and surrounding modelling. The luminance distribution in the surrounding environment was determined using CIE standard sky model and image based lighting (IBL) technique. In IBL method the sky and surrounding environment was defined by high dynamic range (HDR) image. Used HDR images were captured by camera with fisheye lens with 180° viewing angle which enables the projection of the entire hemisphere of the sky and surrounding environment. Determination of daylight conditions were performed for two days characterised by overcast sky conditions. Simulations were conducted using Radiance Lighting Simulation and Visualization software. Obtained results show differences in luminance and illuminance distribution in analysed room for both techniques of sky and surrounding modelling. Reason of the observed divergences is uneven cloud layer distribution at HDR images and influence of surrounding environment visible at HDR images. IBL technique allow more precise modelling of daylight distribution, especially in urban environment where surrounding buildings and vegetation significantly effect on the light availability.