Abstract
What we now know as Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) can be traced back to the 1950s and the first uses of computers in design and manufacturing. The first interactive CAD-type system Sketchpad was demonstrated as early as 1963. However, the price of 3D graphics systems was prohibitive for use in all but the most advanced industries until the end of the 1970s. The CAD of the 1960s and early 1970s was dominated by batch systems using punched cards as input, and pen plotters as output to produce engineering drawings. CAD was used to automate the design of engineering drawing, and to generate NC-programs for controlling machines with numerical controls. The introduction of the Tektronix 4010 storage tube in 1972 drastically reduced the cost of graphics screens, however, they still priced very high compared to current graphics systems. This, however, allowed the input to be interactive, and the results to be displayed on a high resolution screen, the interactive 2D CAD systems for drawing systems emerged.As the design drawings represented 3D shapes, the next step was 3D design systems. The first 3D systems were wire frame oriented, with the shape represented by a network of curves. However, the wire frame did not give a complete description of the geometry, so a further step was to describe the objects by the surfaces constituting the inner and outer hulls. As early as 1962 Pierre Bézier described what are now known as Bézier surfaces for the use in the automotive industry. However, commercial surface based CAD-systems were not widespread until the 1970s. The mathematical approaches were fragmented, and not until the deployment of B-splines in CAD-systems, did a unified approach to surface descriptions in CAD emerge. The theory of B-splines was established in the 1970s with the Cox de Boor algorithm in 1972, and the Oslo Algorithm in 1980.In 1973 Ian Braid in his PhD thesis described the boundary structures for solid models with elementa
