%APN3_PROCEEDINGS_FORM%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% TEMPLATE.TEX -- APN3 (2003) ASP Conference Proceedings template.
%
% Derived from ADASS VIII (98) ASP Conference Proceedings template
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% D.Bohlender for ADASS 2001, and H. Payne for ADASS XII and LaTeX2e.
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\documentclass[11pt,twoside]{article}  % Leave intact
\usepackage{adassconf}

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%\documentstyle[11pt,twoside,adassconf]{article}

\begin{document}   % Leave intact

%-----------------------------------------------------------------------
%			    Paper ID Code
%-----------------------------------------------------------------------
% Enter the proper paper identification code.  The ID code for your
% paper is the session number associated with your presentation as
% published in the official conference proceedings.  You can           
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% EXAMPLE: \paperID{O4-1}
% EXAMPLE: \paperID{P7-7}
%

\paperID{P3-2}
%%%% ID=P3-2

%-----------------------------------------------------------------------
%		            Paper Title 
%-----------------------------------------------------------------------
% Enter the title of the paper.
%
% EXAMPLE: \title{A Breakthrough in Astronomical Software Development}
% 
% If your title is so long as to fill the page header when you print it,
% then please supply a short form as a \titlemark.
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% EXAMPLE: 
%  \title{Rapid Development for Distributed Computing, with Implications
%         for the Virtual Observatory}
%  \titlemark{Rapid Development for Distributed Computing}
%

\title{Organization of Data Sets in Virtual Observatories }
%\titlemark{ }

%-----------------------------------------------------------------------
%		          Authors of Paper
%-----------------------------------------------------------------------
% Enter the authors followed by their affiliations.  The \author and
% \affil commands may appear multiple times as necessary (see example
% below).  List each author by giving the first name or initials first
% followed by the last name.  Authors with the same affiliations
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%
% EXAMPLE: \author{Raymond Plante, Doug Roberts, 
%                  R.\ M.\ Crutcher\altaffilmark{1}}
%          \affil{National Center for Supercomputing Applications, 
%                 University of Illinois Urbana-Champaign, Urbana, IL
%                 61801}
%          \author{Tom Troland}
%          \affil{University of Kentucky}
%
%          \altaffiltext{1}{Astronomy Department, UIUC}
%
% In this example, the first three authors, "Plante", "Roberts", and
% "Crutcher" are affiliated with "NCSA".  "Crutcher" has an alternate 
% affiliation with the "Astronomy Department".  The fourth author,
% "Troland", is affiliated with "University of Kentucky"

\author{Mark G. Allen, Fran\c{c}ois Bonnarel, Thomas Boch, 
        Pierre Fernique }
\affil{Centre de Donn\'{e}es astronomiques de Strasbourg, France}
\author{Mireille Louys}
\affil{Laboratoire des Sciences de l'Image, de l'Informatique 
       et de la T\'{e}l\'{e}detection, France}

%-----------------------------------------------------------------------
%			 Contact Information
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%           \email{crabtree@cfht.hawaii.edu}
%

\contact{Mark G. Allen}
\email{allen@astro.u-strasbg.fr}

%-----------------------------------------------------------------------
%		      Author Index Specification
%-----------------------------------------------------------------------
% Specify how each author name should appear in the author index.  The 
% \paindex{ } should be used to indicate the primary author, and the
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% EXAMPLE: \paindex{Crabtree, D.}
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% NOTE: this information is also used to build the author list that
% appears in the table of contents.  Authors will be listed in the order
% of the \paindex and \aindex commmands.
%

\paindex{Allen, M. G.}
\aindex{Bonnarel, F.}
\aindex{Boch, T.}
\aindex{Fernique, P.}
\aindex{Louys, M.}

%-----------------------------------------------------------------------
%		      Author list for page header	
%-----------------------------------------------------------------------
% Please supply a list of author last names for the page header. in
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%
% EXAMPLES:
% \authormark{Lastname}
% \authormark{Lastname1 \& Lastname2}
% \authormark{Lastname1, Lastname2, ... \& LastnameN}
% \authormark{Lastname et al.}
%
% Use the "et al." form in the case of seven or more authors, or if
% the preferred form is too long to fit in the header.

\authormark{Allen, Bonnarel, Boch, Fernique \& Louys.}

%-----------------------------------------------------------------------
%			Subject Index keywords
%-----------------------------------------------------------------------
% Enter a comma separated list of up to 6 keywords describing your
% paper.  These will NOT be printed as part of your paper; however,
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% for past proceedings (http://adass.org/adass/proceedings/).
%
% EXAMPLE:  \keywords{visualization, astronomy: radio, parallel
%                    }
%
% In this example, the author noticed that "radio astronomy" appeared
% in the ADASS VII Index as "astronomy" being the major keyword and
% "radio" as the minor keyword.  The colon is used to introduce another
% level into the index.

\keywords{Virtual Observatory, metadata, archives}

%-----------------------------------------------------------------------
%			       Abstract
%-----------------------------------------------------------------------
% Type abstract in the space below.  Consult the User Guide and Latex
% Information file for a list of supported macros (e.g. for typesetting 
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\begin{abstract}          % Leave intact
% Place the text of your abstract here - NO BLANK LINES
Browsing and accessing local and distributed datasets
is an important aspect enabling Virtual Observatories. We present
an example implementation of a data tree in the Astrophysical
Virtual Observatory prototype tool. This is a dynamically built
data tree containing information on image datasets, based on
the IDHA data model. We show how the
meta-data representation of the GOODS dataset in the AVO demo allows 
efficient data browsing and selection, and how the tree may be
used to access local and distributed data. This capability is being 
developed in the framework of the CDS Aladin image browser, 
and AVO prototypes.
\end{abstract}

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%			      Main Body
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% Place the text for the main body of the paper here.  You should use
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% EXAMPLE:  \section{Introduction}
%           ...
%           \subsection{Our View of the World}
%           ...
%           \section{A New Approach}
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% It is recommended that you look at the sample papers, sample1.tex
% and sample2.tex, for examples for formatting references, footnotes,
% figures, equations, html links, lists, and other special features.  

\section{Introduction}
Browsing and visualization of image datasets will be an
important part of Virtual Observatory operations. Such
datasets may range from a small set of images stored on
a local disk, to the tera-byte collections of modern
surveys. Standardized and scalable descriptions of image 
metadata will be required to enable dataset browsing, 
selection and visualization.
The data tree that was developed for the Astrophysical
Virtual Observatory (\htmladdnormallinkfoot{AVO}{http://www.euro-vo.org}) 
1st year demonstration represents a prototype implementation of a
scalable, hierarchical metadata description 
(in 
\htmladdnormallinkfoot{VOTable}{http://www.ivoa.net/twiki/bin/view/IVOA/IvoaVOTable}/XML)
for image datasets. The data tree mechanism allows
{\em any} image data available via URL to be described and
accessed via an hierarchical tree. 

Here we provide a very brief outline of the image 
metadata description that forms the basis of this data access 
scheme, and show how the data tree is used in the AVO 
prototype to enable ``smart browsing'' and selection of data.


\begin{figure}   
\epsscale{0.80}
\plotone{P3-2_1.eps}
\caption{The Data Tree in the AVO Prototype. The lower right
Server Selector window shows a request sent to the Aladin image 
server for data available in the CDFS, and the resulting list
of images. This tree is presented in the Treeview window
along with the results of subsequent requests. The fields of
view of images in the tree are interactively shown in the 
top right visualization window, where the images can be selected
and loaded into the image and catalog plane stack. }
\end{figure}

\section{Image Metadata Description in VOTable}
The information requirements for the VOTable description 
of the data tree have been designed to be flexible 
enough to allow for a simple listing of a set of images,
or a rich description based on the 
\htmladdnormallinkfoot{IDHA}{http://cdsweb.u-strasbg.fr/idha.html}
data model. Details on the required, and optional fields, including 
an annotated example are described on the 
\htmladdnormallink{Euro-VO web page}{http://www.euro-vo.org/internal/Avo/MetadataTree/}.
The IDHA data model seeks to provide a generic description
of astronomical data. Using the model as a basis for image
metadata description is beneficial because data described in a 
tree that conforms to the IDHA model schema can be organized into 
nodes corresponding to objects of the model. Also uniform
description of the image metadata (such as 'coordinates' and 'observed 
wavelength') allows software interfaces to make 
use of this information for data browsing and selection.
Such capabilities have been built into the AVO prototype.

\begin{figure}
\epsscale{0.70}
\plotone{P3-2_2.eps}
\caption{Field of view display of the GOODS ACS image tiles. The
original image tiles are shown, along with the currently selected tile.
The small square shows the outline of the image cut-out centred on the 
cursor position, that can be generated by the Aladin image server on request.
}
\end{figure}

\section{The Data Tree in the AVO Prototype}
Figure 1 shows the data tree interface in the AVO prototype.
The hierarchical tree displays information on the image data
available in a given region of the sky. In this example
the tree was dynamically generated by the Aladin image 
server as a result of a request for data within a $\sim$0.5$\arcmin$
radius of the Chandra Deep Field South (CDFS). The results
show the GOODS data (Giavalisco et al. 2004) in the Aladin image
server, including WFI, ISAAC, HST-ACS and Chandra images.
The images are organized by instrument, bandpass and epoch
and the interface provides a mechanism to interactively re-sort
the nodes based on the metadata.

The metadata stored in the tree is utilised
to provide an efficient means for ``smart browsing'' and selection
of data. Browsing the cursor over the tree causes the field 
of view outlines for each tree node to be displayed. An example
is shown in figure~1 where image tiles of a single epoch 
of the CDFS ACS images are overlaid on a WFI image.
Conversely, browsing the cursor over the image highlights nodes in the
tree when data are available at the cursor coordinate. This
interaction between the tree and the image display 
provides an efficient means to simultaneously select all the 
data available at a given point in the sky. 

Image servers that provide image cut-outs are also 
supported by the full IDHA implementation of the
data tree. Figure~2 shows the
fields of view of the original HST ACS image tiles,
plus the outline of the image section that would be
generated if the data request was submitted to the
image server.  

\section{Access to Image Data via Treeview}
In addition to data stored in the Aladin image server,
images available via the Simple Image Access (SIA)
protocol, and indeed any images available via a direct
URL including images on a local disk, may be accessed
and viewed in the tree with their field of view outlines
shown in the display. Interfaces to the SIA servers for 
\htmladdnormallink{SkyView}{http://skyview.gsfc.nasa.gov},
and the 
\htmladdnormallink{NOAO Science Archive}{http://archive.noao.edu/nvo/sim}
have been implemented in the prototype. For example, the result 
of a query  to SkyView for the CDFS is shown in the tree in 
figure~1. Data trees for images available via direct URLs
may be constructed and loaded into the prototype. Such 
trees have been demonstrated for WFPC2 association images 
served from ESO, and for VLA data served from Jodrell Bank.
Data trees for local images may be automatically generated
by specifying the top level directory at the load interface.

The data tree functions developed for the AVO prototype
are also fully enabled in the Aladin 2.0 release (Bonnarel,
Fernique \& Boch 2004).


%-----------------------------------------------------------------------
%			      References
%-----------------------------------------------------------------------
% List your references below within the reference environment
% (i.e. between the \begin{references} and \end{references} tags).
% Each new reference should begin with a \reference command which sets
% up the proper indentation.  Observe the following order when listing
% bibliographical information for each reference:  author name(s),
% publication year, journal name, volume, and page number for
% articles.  Note that many journal names are available as macros; see
% the User Guide listing "macro-ized" journals.   
%
% EXAMPLE:  \reference Hagiwara, K., \& Zeppenfeld, D.\  1986, 
%                Nucl.Phys., 274, 1
%           \reference H\'enon, M.\  1961, Ann.d'Ap., 24, 369
%           \reference King, I.\ R.\  1966, \aj, 71, 276
%           \reference King, I.\ R.\  1975, in Dynamics of Stellar 
%                Systems, ed.\ A.\ Hayli (Dordrecht: Reidel), 99
%           \reference Tody, D.\  1998, \adassvii, 146
%           \reference Zacharias, N.\ \& Zacharias, M.\ 2003,
%                \adassxii, \paperref{P7.6}
% 
% Note the following tricks used in the example above:
%
%   o  \& is used to format an ampersand symbol (&).
%   o  \'e puts an accent agu over the letter e.  See the User Guide
%      and the sample files for details on formatting special
%      characters.  
%   o  "\ " after a period prevents LaTeX from interpreting the period 
%      as an end of a sentence.
%   o  \aj is a macro that expands to "Astron. J."  See the User Guide
%      for a full list of journal macros
%   o  \adassvii is a macro that expands to the full title, editor,
%      and publishing information for the ADASS VII conference
%      proceedings.  Such macros are defined for ADASS conferences I
%      through XI.
%   o  When referencing a paper in the current volume, use the
%      \adassxii and \paperref macros.  The argument to \paperref is
%      the paper ID code for the paper you are referencing.  See the 
%      note in the "Paper ID Code" section above for details on how to 
%      determine the paper ID code for the paper you reference.  
%
\begin{references}

\reference Bonnarel, F., Fernique, P., Boch. T.\ 2004, \adassxiii,
           \paperref{P2-32}
\reference Giavalisco, M. \& the GOODS team, 2003, \apjl\ in press


\end{references}

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\end{document}  % Leave intact
