Provided are a first DSM generating unit, a ground DEM storing unit, a first DEM generating unit, a 2 m ground DEM storing unit, a first DHM generating unit, a first inclination image generating unit, a first inclination image storing unit, a first red relief image generating unit, a first gradient-tinted image generating unit, a first feature height-based colored image generating unit, a first building height comparison image generating unit, and the like. Accordingly, an image does not look dirty, and an image in which a shape of a feature is outlined clearly is obtained.