Generation of Surface Temperature Image in Built Environment Space using the 3D Thermograph and Ray Tracing Method

Abstract

Thermograph shows the radiant temperature distribution of the observed surface, including the influence of the reflection from the surroundings. In this study, the method to generate the surface temperature images from 3D thermograph is developed. First, three-dimensional geometric model of the built environment space is generated by the stereo photography method using spherical thermograph system. The observed thermal images, which have the accurate coordinate information, are matched with 3D geometric model, three-dimensional thermal image is then generated. The directional emissivity and reflectivity data, which are the essential factors for the surface temperature calculation from radiant temperature, are obtained for several architectural materials through the measurement. The influences of reflection from the surroundings on the radiant temperature in the thermal image are removed by the ray tracing in the three-dimensional thermal image using the directional emissivity and reflectivity data, the three-dimensional surface temperature image is then completed. The calculation accuracy of the surface temperatures and the effectiveness of this conversion method are confirmed.