GAIA 3D: Volume Visualisation of Data Cubes

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To complement the already powerful data cube handling facilities of the Starlink GAIA application it has been extended to provide integrated 3D volume and iso-surface rendering.

The result is a simple integrated system with support for astronomy data formats and coordinate systems that limits the initial knowledge necessary to exploit 3D visualisation for data exploration and analysis.

Iso-surfaces

This picture shows the new GAIA toolbox displaying a JCMT dataset (of the central parts of the Orion nebula) using isophotal contours at various levels and with various opacities to render the volume (using opacities allows you to see different depths within the outer volumes). A number of levels can be automatically suggested (based on the data displayed in the main GAIA window), or chosen to give logarithmic intervals. The data can be directly shared with GAIA, unless replacement of bad values is required. This isn't usually the case for contouring. Interaction with the image uses a series of mouse gestures, or the keyboard can be used for finer control. The cardinal directions of the data's world coordinates (in this case RA, Dec and Radio velocity) can be permanently displayed in the current view.

Volume rendering

Picture showing volume rendering of the same dataset as above. The colour transfer function is a simple mapping between two selected colours for the given data range. Volume rendering is sensitive to the presence of bad data values, so any blank values have been replaced with the value zero.

Interaction with GAIA

GAIA currently provides facilities for displaying slices from cubes, and extracting a point spectrum. These positions within the data-cube can now be visualised as a plane and a line. The positions of the plane and spectrum can be changed using GAIA in its traditional mode, or you can now move the plane and spectral line around within the visualised volume. When dragging over the plane a readout of the coordinates (RA, Dec and Radio velocity in this case) is provided, as well as the data value.

Annotated axes

Using the new Plot3D facilities of the AST library, annotated axes displaying labels in familiar sexagesimal formatting can also be displayed. In the picture above you can see one possible way of displaying these shown in a print, rather than a screen capture.


Questions or comments to: p.w.draper@durham.ac.uk.

Copyright © 2005 Central Laboratory of the Research Councils
Copyright © 2006 Particle Physics and Astronomy Research Council
Copyright © 2008-2009 Science and Technlogy Facilities Council
Copyright © 2009-2013 Peter W. Draper
Last modified: 02-Jun-2016
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