RealScape: Metropolitan Fixed Assets Change Judgment by Pixel-by-pixel Stereo Processing of Aerial Photographs

  • Hirokazu Koizumi NEC System Technologies, Ltd.
  • Hiroyuki Yagyu NEC System Technologies, Ltd.
  • Kazuaki Hashizume NEC System Technologies, Ltd.
  • Toshiyuki Kamiya NEC System Technologies, Ltd.
  • Kazuo Kunieda NEC Corporation
  • Hideo Shimazu NEC System Technologies, Ltd.


The Tokyo Metropolitan Government, the largest municipality in Japan, routinely conducts building-change identification work. Recently, Tokyo terminated its traditional visual identification work, which had been used for 20 years, and shifted to a new automated system. This paper introduces the Fixed Assets Change Judgment (FACJ) system and its core tool, RealScape. RealScape automatically detects changes in the height and color of buildings based on three-dimensional (3D) analysis of aerial photographs. It employs a unique pixel-by-pixel stereo processing method and enables a foot-level precision for each building. RealScape detects building changes more accurately than visual judgment operations by humans and reduces the labor costs to one third of the traditional approach and the required judgment duration to about two weeks per 100 km2.