Abstract
The GIS data of sewerage system are made by map digitization. The map digitization could utilize the drawings registers on pages effectively and make the GIS data at low cost. But the map digitization could not get higher precision than the original drawings registers, and the survey method of original drawings registers might be the low precision method that is out of the general standard of operation specifications for public surveys. Authors considered the high precision 3D data consistent with feature to be needed. Therefore, authors made the 3D coordinate values of feature, that were surveyed from the detail survey (map information level 250) utilized the control points produced from the 4th class control point survey, into the high precision 3D vector data using GIS. It was investigated the validity of positional precision surveyed from the detail survey and the control point survey through the discrepancy between the centers of manhole, one is the detail survey result, other one is the geometrically corrected drawings register. Further, it became possible the underground space such as the earth covering and slope of pipe to be grasped visually by using the 3D expression in GIS.
