Sharing images intelligently: The Astronomy Vizualisation Metadata standard
Sharing images intelligently: The Astronomy Vizualisation Metadata standard Robert L. Hurt1, Adrienne J. Gauthier2 Lars Lindberg Christensen3 & Ryan Wyatt4
1
Spitzer Science Center (
[email protected]) Steward Observatory, University of Arizona (
[email protected]) 3 ESA/Hubble (
[email protected]) 4 California Academy of Sciences (
[email protected]) 2
Abstract High quality astronomical images, accompanied by rich caption and background information, abound on the web and yet prove notoriously difficult to locate efficiently using existing search tools. For instance, “flat” searches will return dozens of hits for low-quality images and miss more important related images from large observatories. The Virtual Astronomy Multimedia Project offers a solution via the Astronomy Visualization Metadata (AVM) standard. VAMP manages the design, implementation, and dissemination of the AVM standard for the education & public outreach (EPO)/press astronomical images that observatories publish.
Problems with web images: search and context The astronomical EPO community plays a key role in conveying the results of scientific research to the general public. A key product of EPO development is a variety of non-scientific public image resources, both derived from scientific observations and created as artistic visualisations of scientific results. Images are generally made available in formats such as JPEG, TIFF, PNG, and GIF (i.e., not scientific FITS datasets). Such resources are currently scattered across the internet in a variety of galleries and archives, but are not searchable in any coherent or unified way (nor via machine-generated queries). This issue is described in detail in Gauthier et al. (2007). 450
Communicating Astronomy with the Public 2007
A second problem is that once a search engine retrieves the resources, they are often without the descriptive information (metadata) that can put them into context. It can be difficult or impossible to identify the intended meaning of the image or what is happening astronomically. The image, more often than not, has been ripped away from its original source and thus lacks contextual information such as a headline, description, telescope facility, sky position, etc. The situation is exacerbated if one does not know the originating website of an image file. What object is pictured? What telescope made the observation? How should the colours be interpreted? Where on the sky should it be placed?
Metadata is the solution Metadata is a set of data that describes and characterises another set of data, for instance an image. Such a set of descriptors forms the basis for any structured method for cataloguing content in a database. The Virtual Astronomy Multimedia Project (VAMP) has at its core the Astronomy Visualization Metadata (AVM) standard. This comprises a set of tags to fully describe astronomical imagery, particularly the wealth of high-end image products intended for the non-technical user. The current scope includes telescopic observations, photography (e.g. of telescopes, astronauts, technology, etc.), illustrations/diagrams, and data visualisations. Eventually it will include tags for video and other multimedia content. We are currently working with planetarium professionals to make the AVM accessible and useful for their needs. The categories for AVM tags span the needs for astronomy images, ranging from the general to observation-specific information: 1. Creator: The identity and contact information for the original source of the image. 2. Content: General information about the image including title, subject, and caption. 3. Observation: Source telescopes, instruments, and mappings for colour composites. 4. Coordinates: Sky projection information (World Coordinate System). 5. Publisher: Information on the institution/body providing online access to the image. 6. File: Image dimension, size, format (native information for the file type). The AVM uses the XMP standard from Adobe Systems, a variation of XML. This is the same technique a digital camera uses to record time, date, and exposure information in photographs. AVM builds on the IPTC metadata standards that are widely used in image software and in the publishing industry. The most beneficial aspect of the XMP standard is that the metadata is stored directly in the image header. Therefore, the metadata is attached to the image, regardless of whether it sits on the original source server or has been uploaded elsewhere. Much of the metadata will be immediately available to a casual user: the more general tags under Content and Creator can be accessed by many existing image management programs (e.g. iPhoto, Picassa, etc.). In addition to the general metadata, the astronomy-specific tags are defined as XMP extensions which may currently be read in using custom panels in Adobe Photoshop and Bridge. Developers are currently working on a “Photoshop free” method to creating, editing, and attaching AVM metadata to non-FITS images (e.g. JPEGs, TIFFs, PNGs, etc.). The VAMP Archive will house 451
Sharing images intelligently: The Astronomy Vizualisation Metadata standard
Figure 1 – The AVM version 1.1 (alpha release) metadata tags.
the AVM metadata and online image locations that reside on the content providers servers. The VAMP Service allows for intelligent search strategies of the database that utilise the full contextual information captured within the metadata. Proposed search techniques include cone/positional searches based on WCS information, keyword/text searches, and semantic methods using the controlled vocabularies to find related imagery. The AVM/VAMP Server model will allow dramatic new ways to utilise imagery in innovative applications. For instance, images tagged with sky coordinates could be placed automatically into desktop or planetarium software with the contextual information shown alongside the image or on a planetarium lecturer’s console. Custom web or museum kiosk applications could employ dynamically-updating content based on queries to the VAMP server, drawing on new images as quickly as they are released to the web.
Use AVM now! The architecture for AVM is in place and tools now exist in Adobe Photoshop and FITS Liberator for tagging image libraries. Anyone interested in increasing the flexibility of their image archives 452
Communicating Astronomy with the Public 2007
is encouraged to start tagging their images now and contact the VAMP team for ongoing collaborative efforts. Current progress includes recruiting Spitzer Space Telescope, Hubble Space Telescope (NASA/ESA), and Chandra X-Ray Observatory to tag image collections; agreeing with the IRSA group at Caltech to design, build, and maintain the VAMP Archive and Service; and prototyping using an open source desktop planetarium program (Stellarium, see Kapadia et al, 2007). Growing VAMP partnerships include a cross section of observatories, data centres, application developers and planetariums. For more information about VAMP and to download the most current Astronomy Visualization Metadata standard (Version 1.1) visit our website1. You can also view our IVOA Note, Astronomical Outreach Imagery Metadata Tags for the Virtual Observatory Version 1.00 at Hurt et al. (2006)2. References • Gauthier A.J., Christensen L.L., Hurt R.L., Wyatt R. (2007), Virtual Astronomy Multimedia Project. In Christensen L.L., Zoulias M. & Robson I. (eds.) Proceedings from Communicating Astronomy with the Public 2007 • Hurt R.L., Christensen L.L., Gauthier A. (2006),Astronomical Outreach Imagery Metadata Tags for the Virtual Observatory Version 1.00. http://www.ivoa.net/Documents/latest/AOIMetadata.html (2006). • Kapadia A., Chéreu F., Christensen L.L., Nielsen L.H., Gauthier A.J. Hurt R.L., Wyatt R. (2007), VAMP in Stellarium/ VirGO: A Proof of Concept. In Christensen L.L., Zoulias M. & Robson I. (eds.) Proceedings from Communicating Astronomy with the Public 2007
1 2
www.virtualastronomy.org http://www.ivoa.net/Documents/latest/AOIMetadata.html
453
