2008 NVO Summer School 1

Image Visualization in the VO

Doug Tody (NRAO)Francois Bonnarel (CDS)

THE US NATIONAL VIRTUAL OBSERVATORY

Image Visualization in the VO

• Topics– Review of current tools– Planned capabilities– Close-up look at Aladin

Image Visualization in the VO

• Some Current Tools– Aladin - Image and catalog visualization (CDS)– Oasis - Online archive science visualization services (IRSA)– Mirage - Multivariate viewing of data, including images– SkyCat/JSkyCat - Image and catalog visualization (ESO)

– DS9 (can be driven from IRAF)– IRAF (NVO package provides VO integration via VOClient)– IDL - ATV image display tool, some IDL VO integration– CASA (AIPS++) viewer (radio data; no VO integration yet)

– Karma - Visualization of radio cubes (no VO integration yet)– GAIA 3D - Spectral data cubes, some VO integration– DVR - Distributed volume renderer (some VO integration)– RVO - Distributed radio data cube viewer (SGPS etc.)

Future Capabilities

• Three Approaches– Separately download entire images– Real-time data access (slice, dice, reproject, etc.)– Distributed visualization algorithm

• Further Legacy Software Integration– IDL, IRAF, CASA, etc. (DS9?)

• Data Cube Visualization– SIA version 2 will support cube data access– essential for future instrumentation with Terabyte cubes– subcube, 2D slice, 2D projection, 3D slice, filtering, etc.– Strategy is to retrofit existing client, server tools

The Aladin Image and Catalog Visualization Tool

Aladin and the VO

• We can distinguish several types of usage of VO protocol services by Aladin:

– Direct access to DAL services (mainly SIA) via specific dialog boxes

– Access to VO services (SIA, SSA, cone search) available from the registry…

– Interaction with other VO tools via Plastic…

Direct access to DAL services

• Exempli gratia: access to MAST SIA Image server (or CADC, or SDSS) via their specific dialog box. All metadata will appear in the Metadata tree.

SIA servers

It is also possible to create its own GLU record to create a dialog box towards DAL service ( see eg FAQ «5.5  Can I launch Aladin applet with images or data coming from my own http server?«)  

Direct access to DAL services

• The metadata for a single observation appears in a specific « Info frame » by clicking on the metadatree slot.

Access via the registry

• Use the « All VO «  button. By default you get all that has been registered in the VO registries (except those tested as bad servers) with color code for images, spectra (for these the position are shown on the current image(s)) and sources… It is possible to restrict to any of these categories:

Access via the registry

• It is possible to browse in the list of services (using detailed list), to select one or several VO services

Communication with SAMP (PLASTIC)

• Eg : Topcat, SpecView, VOSpec: to find the main ones go to « Tools » menu and select VO Tools

• Send a spectrum from the metadatree to a specific tool• Identify enlighted sources in a tool on the other one (eg

TOPCAT/Aladin)…• Etc ….