3d Computer Aided Design

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3d Computer Aided Design

• 3D vector graphics

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A working definition

• The use of computers in the design process (from
  the 2d CAD slides)
• 3d CAD facilitates the manufacturing process
• Most modern objects are designed by CAD
• It facilitates modelling and simulation
• Pipe-works, bridges and landscapes for example

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Three Dimensions

• It is a quantum leap from working in 2d to
  working in 3d
• It is more than 2d 1
• Some folks can do this with no problem
• But for some it is a difficult transition
• So how do we explain/demonstrate this?
• A good question

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3d Microstation

• Much the same as 2d, but with 3d elements and
  operations
• A 3d design file is created by using the 3d seed
  file
• Generally a 3d file will open with 4 windows,
  giving different views of the 3d design cube

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The 3d Microstation Screen
Top view
Isometric view
Other 3d menus
Right view
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Basic Drawing Tools

• Points, lines, arcs, ellipses, polygons
• But now they are placed in 3d space!
• 3d Graphic primitives
• Cubes, cones, prisms
• Constructed 3d elements
• Extrusion, rotation, addition and subtraction
• Engineering features
• Chamfers, welds

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Snaps and Locks

• Snap locks determine where a tentative snap will
  jump to
• Other locks are useful for placing elements
• Very useful when working in 3d

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Accurate Input

• MicroStation allows precision input for all
  elements
• Length, orientation, location
• Its can also show dimensions
• Now we have to consider the ACTIVE Z
• The height at which new elements will be placed

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Rendering

• We will cover rendering in later lectures, but it
  will be introduced here as it helps the placement
  of 3d objects
• A simple render fills a wireframe figure with
  shaded solid fill
• See example

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3d Elements
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3d Primitives

• These are the basic building blocks for 3d
• Slab
• Sphere
• Cylinder
• Cone
• Torus
• Wedge

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3d Constructions

• Elements of extrusion
• Elements of rotation
• Extrude along path
• Shell

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Boolean Operations

• Mr George Boole is known for his three operators,
  AND, OR and NOT
• Union, intersection and difference
• Used to develop set theory and Venn Diagrams
• Used by Internet Search Engines too!
• These operators can be applied to solids to
  create new elements
• http//www.cs.huji.ac.il/arir/cda-abs.html

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Boolean Operations
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The Assignment

• The 3d assignment endeavours to cover all th
  necessary aspects of 3d graphics
• Whilst a block of cheese may seem to have little
  to do with Geomatics (apart from goinging very
  well with aged reds, ports and a good Cognac)
• It covers all the necessary aspects

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Irregular 3d elements

• The world is irregular, CAD prefers regularity
• 3d CAD packages do not deal with irregular
  objects very well, but they are capable of some
  operations
• Terrain visualisation (survey add-ons)
• Scan data, reverse engineering

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Summary

• Microstation is a complex package
• It takes a long time to become proficient
• You will learn the basics of using it in 2d and
  3d
• This will be reinforced in later years of the
  course

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The Next Steps

• Adding materials and lights to make realistic
  renders
• Using non-CAD and mesh based modelling systems
• Animation
• Virtual Reality