The Twist Representation of Shape
 @TechReport{rosenhahnTR0407,
   author = {G. Sommer  and B. Rosenhahn and C. Perwass,
   title = {The Twist Representation of Shape},
   institution = {Christian-Albrechts-Universit{\"a}t zu Kiel, 
       Institut f{\"u}r Informatik und Praktische Mathematik},
   type = {Technical Report},
   number = {Number 0407},
   month =      {July},
   year = 2004,
}