Data Acquisition Techniques for 3d Computer Graphics

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Data Acquisition Techniques for 3d Computer
Graphics
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Overview

• We have looked at a lot of computer graphics
  software and techniques
• There are a variety of options for creating 3d
  models
• A CAD approach like Microstation
• A mesh based approach like 3d Studio Max
• There are also techniques for capturing data from
  the real world for processing in modelling
  packages

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Techniques

• Modelling over sketches or photographs
• Field survey
• Coordinate measurement machines
• Photogrammetry
• Laser Scanning
• We will review these as they are relevant for
  Geomatics

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Modelling over Sketches

• Photographs and sketches can be loaded into
  modelling packages to display as a background in
  a view
• The modelling tools are then applied over the top
  of the image to create the model
• Many imaginative characters are created using
  this approach

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Coordinate Measurement

• Instruments designed to measure discrete points
  on an object
• Uses a series of angular encoders to calculate
  the position of the tool
• Small versions available
• Used in the car industry

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Coordinate Measurement
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Field Survey

• Yes, even using a total station to gather
  coordinates of features is a method of capturing
  digital data!
• Data is stored and modified digitally
• Exisiting maps and plans can also be digitised to
  create terrain models
• LOTR used real terrain in the CG scenes

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Olympia
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Gallipoli

• Geomatics and Archaeology have a large project at
  Gallipoli
• It involved looking at 5000 years of human
  occupation
• We need a detailed terrain model of the entire
  peninsula
• How can we do this?

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Photogrammetry

• The art and science of measuring with photographs
• See Photomodeler demo
• See Rectification demo

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Laser Scanning

• Great stuff
• See here for an explanation
• Many different types of instrument exist,
  covering subject sizes ranging from open cut
  mines to artefacts

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Full Body Scanning

• Used to create a digital copy of a real person

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Airborne Laser Scanning

• Uses a similar principle to ground based systems
• Also uses GPS and Inertial Systems to determine
  aircraft position and attitude
• Excellent for creating terrain models