18.1 Visualisation

Contrary to the lower frequencies where continuum emission processes are dominant, mm interferometry most frequently deals with spectral lines, and hence involves handling and display of data cubes. Only a few astronomy packages have been designed for this: GIPSY, GILDAS, MIRIAD. Although the presentation which follows is general enough about the principles (e.g. for the noise analysis or flux density measurements), I will only present the tools which are currently available in GILDAS. Within GILDAS, two display tools are available:
- The GRAPHIC program
- The MVIEW task

In GRAPHIC, easy display is available using the following commands
- GO MAP, for simple channel contour maps
- GO BIT, same with overlaid color bit map
- GO NICE, with clean beam in addition
- GO POS, for Position-Velocity plots
- GO SPECTRE, for maps of spectra.
Easy access to the parameters of these procedures is available through the Windowing interface. GRAPHIC also provides access to all image processing tasks such as UV_MAP, UV_STAT, CLEAN, etc..., and flexible controls for publication quality plots.

Task MVIEW provides a different approach. It is a Window based application which provides simple, intuitive, and fast interactive 3-D data cube display. It provides spectrum display at cursor position, slices, moments, movie features, color manipulation, etc...It also has a direct interface to some important tasks (e.g. moments evaluation, subset extraction) for which interactively selecting parameters using mouse motion is convenient. However, contrary to GRAPHIC, it cannot be customized to produce publication quality images.