The Research Of Testing Daylight Factor On The Method Of Digitalizing Picture Processing

With the improvement of people's living standard, more and more people come to pay much attention to the requirement for natural light in buildings. Recently, research has been conducted all over the world on the use and application of the daylight factor method to determine natural light in building. A daylight factor is defined as the ratio of interior illuminance on a horizontal surface to the exterior illuminance on a horizontal surface simultaneously available outdoors from an overcast sky. Traditional illuminance apparatus cannot satisfy requirement to evaluate daylight environment synthetically. Usually there is time difference between interior illuminance and exterior illuminance which leads to unnecessary errors in testing. The illuminance apparatus can only be used in the overcast sky, but in others conditions, especially with a clear sky, the daylight factor will be affected by the changing daylight. Since the illuminance apparatus cannot effectively analyze components of the daylight factor, there is a great limitation on testing and studying the daylight factor.Therefore, this essay mainly emphasizes digitalization of picture processing method to test the daylight factor. Here is the research on the following aspects:1. The combination of digitalizing picture processing method with the daylight factor theory.2. The testing daylight factor system setting up by using digital camera combined with digitalizing picture processing method can get rid of the influence from the changing of sky conditions and get the daylight factor in the standard luminance of the overcast skies tested under different sky conditions.3. The daylight factor both before and after the blocking can be got when windows are blocked by some external obstruction.4. In the clear sky, the daylight factor is various because the buildings face differently and the position of the sun keeps changing all day long.5. Analyzing all the components (the sky component, the external reflectance component, the internal reflectance component) , which give influence on natural daylight factor, and their functions. That is also called quantification analysis of affecting components on the daylight factor.Developing"the testing program system of natural daylight factor"with Visual Basic according to the basic principle of daylight factor calculation and the digitalizing picture processing method.It is a new technique to use digital camera combined with digitalizing picture processing technique to set up testing system on architectural lighting environment. It has been proved to be able to solve some problems hard to settle in regular ways in recent research.