To automatically group and superimpose upon another three- dimensional coordinate data obtained by measuring an already existing pipeline.

An object 3 to be measured including the already existing pipeline 2 is three-dimensionally measured by means of a laser distance and image measuring apparatus 7 and photographed by means of an image pickup device 1. A piping area 6 is extracted from an image 5 through image processing, and the three-dimensional coordinate data corresponding to the piping area 6 are grouped. Then the grouped three-dimensional coordinate data 10 are modeled by applying a cylindrical surface 12 to the grouped data 10. In expanding the measuring range, the three-dimensional data are measured including the reference target from the view points of a plurality of sensors and superimposed upon another by using the reference target.