This paper presents an overview of our efforts in modeling the Great Buddha of Kamakura through observation. The Kamakura Great Buddha, built in the 13th Century, is one of the national treasures of Japan; of its height is about 20m, including its pedestal. Currently, the Buddha is standing in the open air. We have started this modeling as the kick-off step of our project to model Japanese cultural heritages by using the modeling-from-reality techniques that make virtual models of real objects through observing the real objects. Due to the size and the circumstance concerning the great Buddha, we have encountered several research issues. For geometric modeling, we have developed a simultaneous registration and parallel volumetric merging algorithms. For photometric modeling, we have developed a new camera-sensor alignment algorithm. We have constructed a CG model of the Main Hall of the Great Buddha, widely briefed its existence from the literature survey, and created a video of the Buddha, measured and constructed with our techniques, in the virtual Main Hall created through the literature survey. We have demonstrated the effectiveness of the algorithms as well as the importance of restoring cultural heritage through these techniques.