On a topographical map of civil engineering, there are various enclosed areas, for instance, rice fields, meadows, buildings, roads, walls, regional boundaries and so on. Before a software system such as road planer is run, it is necessary to extract these various regions and features, and to transform them to 3D data. The automatic extraction and classification of all of them on a screen are difficult and very time-consuming. It is better to combine the automatic recognition with interactive operation. It is obvious that interaction is easily done when vector date of maps is applied. On the other hand, the vector data is much less than the raster data of the same map. This paper proposes a practical solution for understanding of vector maps, including two major methoeds; ditching (DIrected Track stretCHING) method for open regions (e.g., roads, slopes and walls etc.) and inward tracing method for bounded regions (e.g., various fields).