CAD Data Structures

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CAD Data Structures
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Modern System Implementation

• Object oriented, defining both data and functions
  of the object.
• Advantage object class can be redeveloped
  without affecting the rest of the system.
• An object can represent concrete things, such as
  a building part, a window with parameters etc.
• Object class can be more abstract, such as a
  relation between a window object and a wall
  object.
• A modelling command is also implemented as an
  object a modelling object call the relevant
  functions in the objects that take part in the
  modelling system.

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Implementation in CAD systems

• CAD systems are developed by the CAD vendor.
• They allow the advanced user to adjust and expand
  the the system to a more specific use.
• In AutoCAD it is ObjectARX that gives access to
  add new classes on top of existing classes.

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Data Exchange in the Building Industry

• What we want? A quality system to achieve
  cost-effective electronic data exchange
  protocols to ensure uniform exchange of
  informationsection on quality assurance to
  provide QA techniques, especially for CAD
• The aim is to improve the information and
  communication by making agreements for exchange
  data about building projects between building
  partners.

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Industry Foundation Classes

• The International Alliance for Interoperability
  (IAI), which set up a Chapter in the UK in 1996, 
  is creating a system of sharing data, which saves
  time and is cost effective. Every object within a
  building, whether a wall, a door or a light
  switch, is given a specification as part of a
  global common language for developing a building
  project. These Industry Foundation Classes, which
  form the building blocks of IAI work on
  interoperability, are explained.

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VGBouw standard

• Layers.htm

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GB CAD- standard

• Realization of sructured data separation in
  CAD-drawings.
• Classification in main groups
• General
• Architecture and Design
• Construction and civil engineering
• Urban development
• Mechanics
• Electrical engineering

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AutoCAD data structureslayers, object
properties