Light Chimney Geometry_Generating the Subtracted Form

Light Chimney Geometry Diagram from subtect on Vimeo.


This video diagrams how the form of the central chamber as shown was derived. Using the sun path as the initial construction line, a secondary circle is positioned along the sun path, one per hour, with a diameter related to the initial sphere of the central chamber (shown in red). The light chimneys are then positioned around this secondary circle, the result being that the light chimneys are offset just far enough to graze the perimeter of the central chamber. Most of the interior of the chamber is never hit with direct light, it is only lit through diffuse light reflected in from surfaces around its perimeter. The intersections between the chimneys and the chamber quickly become quite complex, particularly as they increase in density to the point of intersecting primarily with each other. Every variable of this geometry -- from the amount of offset from the perimeter of the central sphere, to the number of chimneys per hour, to every dimension of the light chimneys themselves -- are controlled parametrically. However, each of these settings was manually set through a hybrid parametric/manual process of trial and error. Without parametrically defined geometry, the design process simply wouldn't have been possible.

The final form orbited here is the negative to be subtracted from the greyed out mass shown at the beginning of the video, resulting in the form shown in the Orthogonal Orbit video posted previously.

Screen capture of the Grasshopper3D definition used to produce the form shown above: