Acronym: Computer Aided Design
The 1970s started with simple 2D CAD software programs such as CADAM. Research and commercial interest in 3D CAD software was rapidly gaining momentum and one of the most influential pieces of research of the decade was in complex 3D surface modeling for CAD software. K. Vesprille's (at Syracuse University) 1975 PhD dissertation "Computer-Aided Design Applications of the B-Spline Approximation Form", built on the 1960s research of de Casteljau, Bezier, Coons and Forrest and earlier (1973) work by R.F.Risenfeld (also at Syracuse University) and continues to be one of the foundations of complex 3D curve and surface modeling in 3D CAD software to this day.
The first 3D solid modeling program, SynthaVision from MAGI (Mathematics Application Group, Inc.) was released in 1972, not as CAD software but as a program for performing 3D analysis of nuclear radiation exposure. SynthaVision's 3D models were solid models similar to the CSG (constructive solid geometry) models used by later 3D CAD software. In general though, and despite steadily increasing computer performance, solid modeling was still too compute intensive for most practical applications. Extensive solid modeling research was done by Charles Lang's group (at Cambridge University) and by Herb Voelcker and his team (at the University of Rochester's Production Automation Project) throughout the decade and the approaches taken throughout the 1970s by the two groups were fundamentally different, as were the CAD software products ultimately based on their research.