Introduction to Visualization

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ACRL Seminar Series
Introduction to Visualization
Chris MacPhee Scientific Computing
Support Advanced Computational Research
Laboratory University of New Brunswick
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Outline
Introduction Visualization pipeline Visual
representation of data Introduction to
OpenDX Visualization techniques Advanced
visualization techniques Summary
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Introduction
What is Visualization?
Visualization is a method of computing. It
transforms the symbolic into the geometric,
enabling researchers to observe their simulations
and computations. Visualization offers a method
for seeing the unseen. It enriches the process of
scientific discovery and fosters profound and
unexpected insights. In many fields it is
revolutionizing the way scientists do
science. - Visualization in Scientific
Computing, ACM SIGGRAPH, 1987
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Introduction
Why use Visualization?
A picture says more than a thousand words. A
picture says more than a thousand numbers. The
purpose of scientific computing is insight, not
numbers. - Dr. Richard Hamming, Naval
Postgraduate School, California ... half of the
human brain is devoted directly or indirectly to
vision ... - Prof. Mriganka Sur, Brain and
Cognative Sciences, MIT
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Visualization pipeline
Visualization pipeline

• read / generate data
• apply visualization algorithms (filters)
• - modify the data
• map results to graphic primitives
• - points, lines, polygons (triangles,
  quadrilaterals) ...
• render the results

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Visualization pipeline
Visualization pipeline
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Visual representation of data
Data v.s. information
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Visual representation of data
Remember context!
Context is needed to transform data into
information. Components of context - Title -
Axis labels - Curve differienciation using line
quality and/or colour - Legend - Text
annotations
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Visual representation of data
A better graph...
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Visual representation of data
1931 CIE Chromaticity Diagram
Courtesy of Peter Kaiser, York University
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Introduction to OpenDX
What is OpenDX?

• OpenDX is an open source visualization tool based
  on IBM's Visualization Data Explorer
• OpenDX is free and cross-platform
• Can be found at http//www.opendx.org

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Introduction to OpenDX
Starting up OpenDX
First step
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Introduction to OpenDX
Describing the data type
Grid types - regular grid data at regular
intervals (implicit) - partially regular,
warped regular, scattered data data not
at regular intervals (explicit) We'll focus on
regular grids (most common).
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Introduction to OpenDX
Describing the data file
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Introduction to OpenDX
Creating the visualization program
Second step
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Introduction to OpenDX
Creating the visualization program
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Introduction to OpenDX
Importing data
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Introduction to OpenDX
Adding colour
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Introduction to OpenDX
Colourmap editor
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Introduction to OpenDX
Creating an image
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Introduction to OpenDX
The image!
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Introduction to OpenDX
Adding annotation
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Introduction to OpenDX
An image with annotation
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Introduction to OpenDX
Customizing colour
Hint for UNIX users Parse your data from your
coordinates, then run cat datafile sort -n
uniq -c
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Introduction to OpenDX
Am image with better colour
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Visualization techniques
Visualization techniques
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Visualization techniques
3D images (Rubbersheet)
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Visualization techniques
Changing perspectives
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Visualization techniques
Contour lines and surfaces (Isosurface)
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Visualization techniques
A contoured fractal image
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Advanced visualization techniques
Advanced visualization techniques
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Advanced visualization techniques
Contour lines and surfaces in 3D (Isosurface)
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Advanced visualization techniques
Moving from 3D to 2D (MaptoPlane)
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Advanced visualization techniques
Warping grids (Compute)
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Advanced visualization techniques
Vectors (Glyph)