Spline technology
The elastic wooden ruler used when designing ships before the computer was introduced as a tool is named a spline. To impose interpolation of given points, weights were put on the spline to control the shape of the spline. Between the weights the spline curve is very smooth. However, close to the weights there is a rapid change in the variation of curvature. Mathematical curves constructed of polynomial pieces joined with controlled continuity are denoted splines due to their similarity to the original physical spline. Spline technology include such curves as well as generalizations to rational descriptions, surfaces and higher dimensional descriptions.
SINTEF is one of the milieus worldwide with the longest traditions within spline technology. When the first Norwegian computer, NUSSE, was ready for use in 1954 applications within ship design and manufacturing were among the first problems addressed. The work focused on the geometric description of ships and ship hulls. In the 60-ies Even Mehlum at SI (SI was merged with SINTEF in 1992) developed nonlinear spline that is a mathematical dual of the physical spline. Parallel to this development spline technology based on piecewise polynomials emerged at different industries and universities worldwide. At the start of the 70-ies Tom Lyche (currently professor at the University of Oslo) travelled to US for his doctorate studies. During this stay he met the cutting edge of spline research within polynomial splines. When returning to Oslo the basis for the current spline activity in Norway was established. In 1976 the first master level courses within splines was given at the University of Oslo. Tor Dokken (now Research Director for the Geometry department of SINTEF Applied Mathematics) was one of the five students following the lectures. Tor was employed at SI in 1978, and this is the start of the Geometry department at SINTEF. In 1979 Richard Riesenfeld and Elain Cohen from the University of Utah visited SI. During their stay they met Tom Lyche and a very good and still strong research cooperation was established. The first result was the Oslo Algorithm that is central in all spline-based computer systems. Parallel to the basic research within splines at the University of Oslo, projects addressing industrial problems using spline technology were initiated at SI. Around Tor a group of research scientists addressing industrial geometry challenges within Computer Aided Design (CAD) gradually evolved. From 1988 this activity has been organized in a separate department, now named department of Geometry. The department started out with CAD-related problems. Today a wide range of use of geometry on computers is addressed, including modelling of human shapes for medicine and games, visualization of large quantities of data, as well as geology.
