Building Translation Surfaces in Rhino

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Tutorial 2.0

• Building Translation Surfaces in Rhino

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Getting Started This assignment asks you to
explore the following concepts Isoparametric
curve An isoparametric curve is a curve of
constant U or V value (X or Y value) on a
surface. Rhino uses isoparametric curves and
surface edge curves to describe the shape of a
NURBS surface. Subsequently, surfaces of
different curvatures have different isoparms.
This project allows you to exploit this
difference to create a coherent and elegant
geometry that describes both surfaces. Wireframe
Wireframe view is how Rhino displays objects
while you create them. Surfaces and solids are
represented as 3-D curves that look like wires
wrapped around the surface. The wireframe
consists of border curves and isoparametric
curves.
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• Getting Started
• The following operations are useful in creating
  Translation Surfaces.
• Extract Isocurve (Isoparm)
• Extract WIreframe
• Boolean Interesection
• Intersect
• Divide
• Duplicate Edge

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• Extract Isocurve
• Command Line ExtractIsocurve
• Select a surface
• Rhino will display Isoparm Curves at the point
  where your selection tool touches the surface.
• At the Select Isocurve to extract prompt, you
  will notice that it specifies
• (Direction U). If you type D, you can
  either change the direction of the extraction to
  V or you can extract in both the U and
  V simultaneously.

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• Boolean Intersection
• Command line ExtractWireframe
• To intersect objects
• At the Select first set of surfaces or
  polysurfaces prompt, select the first object, and
  press enter.
• The prompt asks that you select the second set
  of surfaces or polysurfaces prompt, select an
  object to intersect. Then press enter.

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• Problems With Boolean Intersection
• Coincident Control Points
• For Boolean to work, the control points at the
  edge of a surface cannot be in the same location.
  I.e. your objects cannot be tip to tip.
• Overlapping Surface Area
• When two surfaces share the same area, the
  Boolean Command will not work.
• If you still cant figure it out..
• Hack it! Explode the surfaces and try Trimming,
  Splitting and Joining Back together (re tutorial
  1)

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• Intersect
• Command Line Intersect
• At the Select objects to intersect prompt,
  select the objects. A curve or point object at
  the intersection of the two objects is created.
• Divide
• Command Line Divide
• Select objects to divide and press enter.
• The prompt asks you to enter the number of
  segments. Type a number and press enter.
• Duplicate Edge
• Command Line Dup Edge
• At the select edges to duplicate prompt, select
  the edges of the surface. Each edge is duplicated
  as a separate curve.
• Note these can be joined into a single curve
  using the Join command.

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Examples Intersecting two Tori
Create two tori with the Torus command.
Rebuild the two Tori with the Rebuild command to
add more isocurves to the wireframe. The dialogue
box asks you to specify a number of parameters. I
only altered the point count, changing it to 20
in both U and V.
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Boolean Intersect the two Tori to create a new
object.
Duplicate the edge of the newly-created
polysurface (DupEdge command). Join the edges
into a single curve (Join command).
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Now that the line of intersection is duplicated,
I exploded the polysurface (the object) into
individual surfaces. We see the line of
intersection, represented by the red curve. With
this in mind, I join the edges (JoinEdge command)
of the two sides of the object. What was once a
single polysurface is now two independent
surfaces that share a line of coherence at their
intersection. I then extract the isocurves of one
side (ExtractIsocurve command), and turn off the
isocurves of the other side. To do this, I open
the properties menu (properties command), select
the surface, and un-check the show isocurves box.
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To recap, I have two surfaces on the surface on
the right, I extracted the wireframe (i.e. the
green lines), and on the left, the surface
without isocurves. On the side with its isocurves
off, I begin to extract isocurves
(ExtractIsocurve command) in the U direction that
coincide with the endpoints of those of the
extracted wireframe on the other side. If this
isnt clear, I use the right surface as the
parent surface, and use it to determine where I
extract isocurves from the child surface on the
left. If this still isnt clear, come talk to me.
Nevertheless, I repeat the process for to create
isocurves in the V direction for the left surface.
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• Notes on Building your Models
• To orient your panels in plan, you might try
  using the Orient3pt command. To do this, first
  create a horizontal reference plane. Then type
  Orient3pt, and follow the command prompts (chose
  3 points on your panel, these would probably be
  endpoints, then chose three points on your
  reference plane).
• Figure out a way to annotate your pieces. You
  can do this by placing texts on your planes in
  the model before you orient them in plan.
• Keep in mind that surfaces in rhino have no
  dimension, and real models do. Youll have to
  deal with this in some capacity when building
  your models.

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• More Notes, and Suggestions, and Other Things To
  Consider
• My example and the list of commands Ive provided
  for you are merely suggestions for were to begin
  in tackling this project. They are by no means
  meant to be prescriptive, rather, I want to show
  you how I might start this small project. Try new
  commands, and invent new processes.
• That said, also experiment with other primitives
  (spheres, cones, etc.) and see what you can do.
  Also, its helpful to be quasi scientific about
  your own process. By that, I mean take note of
  what youre doing- to what degree am I
  intersecting primitives? How do size, shape and
  the relative orientation of my original objects
  influence the one I create?
• Part of the role of these explorations is to see
  how your own conceptualization of these objects
  differs from the way that Rhino understands them.
  Between the two is a resonance, and part of this
  exercise surely involves exploring this
  difference.
• As Val Kilmer explains in one of my favorite
  movies,
• Real Genius, sometimes small setbacks give us
  the
• opportunity to make large leaps forward. Find
  comfort
• in this- youll be very pleased with what you
  create.
• And with that, Best of Luck!