This document discusses geometric modeling techniques, specifically focusing on solid modeling and drafting packages. It outlines the salient features of solid modeling, including feature-based design, modeling tools, and characteristics of solid modeling packages. It also describes the features of drafting packages, such as drawing utilities, dimensioning, entities, and drawing interchange files. Finally, it briefly discusses surface modeling and curve and surface representations.

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Geometric Modeling Techniques
chapter 6
SALIENT (PRINCIPAL) FEATURES OF
SOLID MODELING

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Salient Features of Solid Modeling
• Feature based design
• Modeling tools
• Characteristics of solid modeling packages
Feature based design
Sk t h b dSketch based

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Feature based design
Pick and place

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Modeling tools
• Sketching (2D)
• Creating part
• Assembly
• Documenting design
Characteristics of SM package
• Parametric design
• Relations and relationships
• Behaviour modeling
– Smart models
– Engineering objective based design
O t ibl i t– Open extensible environment

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Relationship
Relationship

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FEATURES OF DRAFTING PACKAGES
Features of Drafting Packages
• Drawing utilities • Dimensioninga g u es
• Entity drawing
• Edit commands
• Standard parts
• Display
e s o g
• Plotting
• Configuration
• Customization
• Drawing Interchange
• Cross hatching

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DRAWING UTILITIES
Drawing Utilities
• Screen size
S li
• Specifying points
Li t t t f t• Scaling
• Grid
• Snap
• Units
• Line type, text fonts,
and shapes
• Layers
• Saving a drawing
• File utilities

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Layer
ENTITIES

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Entities
Tugas: baca sub‐bab di bawah ini
• Edit commands
• Block and symbols
• Display
• Cross hatching and pattern filling

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DIMENSIONING

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3D DRAWINGS
3D Drawings
• Extrusion (linear sweep)
• Revolution
• Using UCS (user coordinate system)

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Tugas: belajar sub‐bab di bawah ini
• Plotting a drawing
• Configuring the drafting software
• Customization

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DRAWING INTERCHANGE FILE

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DRAWING OFFICE MANAGEMENT
Drawing office management
• Creation of parts list
Bill f t i l (BOM)
• Project costing
P d t i ti• Bill of material (BOM)
• Searching for similar
design
• Design changes
• Replacing faulty
• Product variations
• Web enabled softwares
• Integrated drafting,
design, and
documentations
components

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SURFACE MODELING

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CURVE AND SURFACE
REPRESENTATIONS
Generic Form
  0f   0,, zyxf

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Parametric form
Properties of parametric reps

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CURVE & SURFACE DESIGN
Design of curve shapes
• Mathematical representation of shape
• Minimum computation
• Ability to generate a CNC program

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PROBLEMS WITH SPLINE
INTERPOLATION
Criteria of curve modeling
• Axis independence
• Global and local control
• Smoothness of curves
• Versatility
• Continuity between adjoining segments of
curves

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CUBIC SPLINES – POLYNOMIAL
BASIS
Hitung persamaan curva 3D:
1 X(0) i t l i l1.X(0) – interpolasi awal
2.X(1) – interpolasi akhir
3.X’(0) – singgung awal
4.X’(1) – singgung akhir

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LIHAT HALAMAN 156
page 159
BEZIER CURVES – BERNSTEIN BASIS