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Explore the innovative process of creating Viae Globi sculptures on a sphere using CAD tools and geometric principles. Learn how to model the Pax Mundi design and bring it to life through a detailed workflow.
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CS285 Designing Viae Globi (Roads on a Sphere) Carlo H. Séquin University of California, Berkeley Inspired by Brent Collins Gower, Missouri
Brent Collins’ Pax Mundi1997: wood, 30”diam. 2006: Commission from H&R Block, Kansas City to make a 70”diameter version in bronze. My task: to define the master geometry. CAD tools played important role.
How to Model Pax Mundi ... • Already addressed that question in 1998: • Pax Mundicould not be done withSculpture Generator I • Needed a more general program ! • Used the Berkeley SLIDE environment. • First: Needed to find the basic paradigm
Sculptures by Naum Gabo Pathway on a sphere: Edge of surface is like seam of tennis- or base-ball; 2-period Gabo curve.
2-period “Gabo Curve” • Approximation with quartic B-splinewith 8 control points per period,but only 3 DOF are used (symmetry!).
4-period “Gabo Curve” Same construction as for as for 2-period curve
Pax Mundi Revisited • Can be seen as:Amplitude modulated, 4-period Gabo curve
SLIDE-GUI for “Pax Mundi” Shapes Good combination of interactive 3D graphicsand parameterizable procedural constructs.
2-period Gabo sculpture Tennis ball – or baseball – seam used as sweep curve.
Viae Globi Family (Roads on a Sphere) 2 3 4 5 periods
Sweep Curve Generator: Gabo Curves as B-splines Cross Section Fine Tuner: Paramererized shapes Sweep / Twist Controller Modularity of Gabo Curve Generator
How do we orient, move, morph ...the cross section along the sweep path ? Sweep / Twist Control Natural orientationwith Frenet frame Torsion Minimization:Azimuth: tangential / normal 900° of twistadded.
Extension: Free-form Curve on a Sphere Spherical Spline Path Editor (Jane Yen) Nice smooth interpolating curves through sparse data points
Extending the Paradigm:Aurora-M • Simple path on sphere, • but more play with the swept cross section. • This is a Moebius band. • It is morphed from a concave shape at the bottom to a flat ribbon at the top of the flower.
Target Geometry • Constraints: • Bronze, 70” diameter • Less than 1500 pounds • Less than $50’000 • Maintain beauty, strength • Minimize master geometry
Use smoother quintic spline Make 4 identical parts(needs extra control point) Add a few “warp” parameters Emulation
Use 4 copies. Emulation; Define Master Pattern • Master to make a mold from. Alignment tab
4 pieces make the whole sculpture Model of Master Part Made with FDM
Joe Valasek’s CNC Milling Machine • Styrofoam milling machine
Alignment tabs for easy assembly Design of Two-Part Master
Front Door H&R Block Building