CALPAS4: four years later

In a paper presented at the 1985 predecessor of this conference, I maintained that current PC microcomputer technologies provided the opportunity to develop a new generation of graphically oriented, interactive building modeling programs. Our efforts to implement one such program, called TAKEOFF, have not been an unqualified success but do provide lessons about this type of program. Generally, the technical proficiency required by interactive graphic programming is in another realm when compared to that required for "simple" building modeling. The paper reviews some of the problems encountered during the development of TAKEOFF.