This paper proposes a new method for automatic fire detection in cities using image processing techniques. Images are obtained successively at regular intervals from monochrome TV cameras which are suitably fixed on roofs of tall buildings. Fire detection is camed out by identifying smoke in the daytime and fire flames at night. The major feature of the proposed method is to employ a fire identification strategy which is applicable to both smoke and fire flames and efficiently uses geographic information for identifying fire location. The strategy is as follows; changing regions are extracted as fire region candidates by image subtraction operation. Motion analysis based on changing region tracking is camed out. As a result, actual fires are discriminated from disturbing events such as swaying trees, moving cars, etc. It is thought that smoke or fire flames might be detected in fragments due to noise. Fire spreading inference based on geographic information is adopted for top down gro...