17. A computer readable storage medium storing a program controlling a computer by: extracting information related to surfaces from a plurality of plan views; generating candidate surfaces based on the information extracted by said extracting; obtaining intersecting lines among the candidate surfaces, and generating modified candidate surfaces, the modified candidate surfaces having candidate edge lines defined by the intersecting lines; generating candidate solids by determining combinations of the modified candidate surfaces; and collating the candidate solids with the plan views and automatically selecting a matching candidate solid from the plan views as a solid model.
17. A computer readable storage medium storing a program controlling a computer by: extracting information related to surfaces from a plurality of plan views; generating candidate surfaces based on the information extracted by said extracting; obtaining intersecting lines among the candidate surfaces, and generating modified candidate surfaces, the modified candidate surfaces having candidate edge lines defined by the intersecting lines; generating candidate solids by determining combinations of the modified candidate surfaces; and collating the candidate solids with the plan views and automatically selecting a matching candidate solid from the plan views as a solid model. 18. The storage medium as claimed in claim 17, further deleting, out of the modified candidate surfaces, at least one of the modified candidate surfaces having a candidate edge line which cannot possibly exist as a solid.