5. Spans & Parabolas
This final chapter about pleats shows how a sheet can be used to create spans and parabolas that touch the ground along an edge or at a corner, and then, through a progression of folded angles, rise upwards, across and down to create a form which resembles a canopy, roof or span.
Whereas most folded spans are ‘simple curves’ which curve in only one direction, like a cylinder, a folded parabola is a ‘complex curve’ which curves in two directions, like a sphere. Of course, the apparent curves of a folded span or parabola are purely illusory, since all the folded edges are straight and the planes between them are flat.