A Solid Modeling Fable

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A Solid Modeling Fable

• Ahmedabad-Visual Design Office
• Kolhapur-Mechanical Design Office
• Saki Naka Die Manufacturer
• Lucknow- Soap manufacturer

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Ahmedabad-Visual Design

• Input A dream soap tablet
• Output
• Sketches/Drawings
• Weights
• Packaging needs

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Soaps
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More Soaps
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Ahmedabad (Contd.)
Top View
Side View
Front View
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Kolhapur-ME Design Office

• Called an expert CARPENTER
• Produce a model (check volume etc.)
• Sample the model
• and produce a data-
• set

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Kolhapur(contd.)
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Kolhapur (contd.)

• Connect these sample-points into a faceting
• Do mechanical analysis
• Send to Saki Naka

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Saki Naka-Die Manufacturer

• Take the input faceted solid.
• Produce Tool Paths
• Produce Die

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Lucknow-Soaps

• Use the die to manufacture soaps
• Package and transport to points of sale

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Problems began

• The die degraded in Lucknow
• The Carpenter died in Kolhapur
• Saki Naka upgraded its CNC machine
• The wooden model eroded

But The Drawings were there!
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So Then.

• The same process was repeated but
• The shape was different!
• The customer was suspicious and sales dropped!!!

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The Soap Alive !
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What was lacking was

• A Reproducible Solid-Model.
• Surfaces defn
• Tactile/point sampling
• Volume
• computation
• Analysis

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The Solid-Modeller
Representations
Operations
Modeller
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The mechanical solid-modeller

• Operations
• Volume Unions/Intersections
• Extrude holes/bosses
• Ribs, fillets, blends etc.

• Representation
• Faceted Solid
• Cloud of Points
• STEPP
• Boundary-Rep (b-rep)
• .sldprt

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Examples of Solid Models
Torus
Lock
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Even more examples
Bearing
Slanted Torus
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Examples (Contd.)
Solid Model of an Ice-Cream Machine
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Sample Representations
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Other Modellers-Surface Modelling
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Chemical Plants

• Design Rules
• -process rules
• -tolerances
• Civil-Mechanical
• Co-Design
• -facility design
• -accessibility
• -safety

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Chemical plants (contd.)
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Chemical Plants (contd.)
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Advanced Surface Modelling
Human Cortex
Manual Surface Sampling,/ model consists of
24,000 planer facets
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Advanced Surface Modelling (Contd.)
The above surface model was created by using the
software tool (Nuages) by Bernard Geiger
Voxel based re-construction shows the surface
decimated to about 22500 vertices and 45000
triangles
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Our Course-Theory

• Topology-combinatorial entities and their
  relationships
• Geometry- parametrizable entities and their
  representations
• Operations- some of them and their
  implementations
• sourcewww.cse.iitb.ac.in/sohoni CAGD
  course notes

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Our Course-Applications

• Basic solid-modelling
• Design Trees and re-parametrization
• MIL (B-rep) and geometry

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Course Schedule
Time AM AM PM PM
Day 1 SM-Fable.ppt SM-Primer.ppt SM-Practical Tutorial 3d
Day 2 SMInternals.ppt Geometric-Topology Polynomials.pdf Tutorial polynomials
Day 3 Curves.pdf Surface.pdf Application I Tutorial Curves and Surfaces
Day 4 Spline.pdf Operation.pdf Application II Tutorial Opns/Cons.
Day 5 Construction.pdf Wrap-Up ApplicationIII TEST
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Contents I
SM-Fable Motivate SM, examples SM and structure of SM
SM-Primer Practical introduction to an SM
SM-Internals Kernel/Husk dichotomy. Entities-face/edge/co-edge. Topology and applications
Geometry-Topology The two-tier representation. Parametric vs. Implicit. Sample parametrizations, trim curves
Polynomials Polynomials and the approximation problem, lagrange interpolation, and the bernstein base
Curves The construction of Bezier-Bernstein curves, control polygons, end calculations, elevation
Surfaces The 2d analogue of bernstein. Tensor-product surfaces, end conditions
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Contents II
Splines The piece-wise polynomial paradigm, knot insertion and evaluation
Operations TheNewton/Raphson Solver, the projection problem, intersections
Constructions The constructor, intersection curves, extrudes, blends