UAVを用いたBRFを考慮したオルソ画像生成手法

抄録

Observation data using optical cameras are affected by shadows and reflectance characteristics. Several methods have been proposed to correct shadows caused by topography and canopy shape. Bi-directional reflectance distribution factor (BRF) as correction factors due to reflectance characteristics have not yet been established in areal Unmanned Aerial Vehicle (UAV) observation. To compute the BRFs, the Digital Number was obtained from the original image. The angle information was lead from the camera information and position and orientation information by SfM application. BRF analysis was performed on a pixel-by-pixel basis by superimposing the Digital Number and angular information of each original image on the projection plane. Developed method takes advantage of the multidirectional observation feature of UAV to obtain BRFs in an areal manner. The image is then generated considering the BRFs. The ortho image generated from the BRF has a uniform relationship between light source position and viewing angle, minimizing shadow effects at forward-light viewing angles. The uniqueness of this research is that it proposes an inexpensive areal BRF observation method. And it contributes to understand geophysical properties of geological features and to improve the accuracy of optical camera imaging.