Abstract: On the utilization of the underground space with major projects, digital mapping based on the secondary development of MAPGIS by C++ Build connected with automatic drawing of histograms and profiles has important significance. By combined with the development of underground environmental information system of Water Supply Reconstruction Project from Dongjiang to Shenzhen in China’s Guangdong Province, China, the function design of automatic digital mapping module and data searching methods as well as automatic drawing methods of histograms and profiles are emphatically introduced. Data searching is emphasized on data organization form and synergistically searching way on multi-database; histogram drawing is developed two ways i.e. fixed table drawing and dynamic data filling; profile drawing is focused on another two ways i.e. elastic-liked realization method of profile lines and data calculation methods of profile data etc. In the application of digital mapping methods to a major project, Water Supply Reconstruction Project from Dongjiang to Shenzhen, the results show that the methods have some advantages such as high automatic extent, large efficiency and high accuracy and also has a better correcting capability. The research has a great value for the development of design and realization of digital mapping in engineering fields.

Key words: secondary development of GIS, digital mapping methods, engineering geological profiles, borehole histograms, application to engineering