Web + VO + Database Technologies = HLA Footprints STScI: Gretchen Greene, Steve Lubow, Brian McLean,...
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Transcript of Web + VO + Database Technologies = HLA Footprints STScI: Gretchen Greene, Steve Lubow, Brian McLean,...
Web + VO + Database Technologies = HLA Footprints
STScI: Gretchen Greene, Steve Lubow, Brian McLean, Rick White and the HLA Team
JHU: Alex Szalay and Tamas BudavariNVO
Astronomical Application
Archival Research is a value added product to observation planning as well as data mining
Has HST observed in this location of the sky?Which wavelength?, how long?, what instrument?, what was the exact coverage with respect to object XYZ?
Show the coverage for a high level product, e.g. Hubble Deep Field, GOODS mosaics, ALL overlapping ACS exposures of a specific fieldI have a transient even (e.g. VOEvent notification), what is the coverage in HST?How does HST coverage compare to another observatory coverage?Large scale distributed spatial queries
NVO search portal
HST Footprints in the HLA
HLA Footprints are spatially precise geometric descriptions of the HST observed areas in the skyCurrent holdings include reprocessed ACS fields (~20% of the completed observations), all sky WFPC2 and STIS
In transition are NICMOS, remaining ACS, FOS & GHRSCollaborations in process with NICMOS grism spectra, SPITZER….
Accessible via web client or programmatic interfaces
Widespread Footprint Development
GALEX (STScI )NOAO VO PortalAladin (via APT)
IVOA (International Virtual Observatory) note for Footprint Overlay specification
VOServices (JHU)
Sky section or image plane: pans, zooms, downloads data.
The (GALEX) MAP - (adaptable to other missions)
Web components
Web portal built on a suite of web services (SOAP, http) using SOAReusable components mostly in form of XML
User requirements reduced significantlyNetwork access & a browser (FIREFOX)No installation required
Technologies are independent of platform and consistent with everyday lifestyle
XML, XSLT processors, Javascript, ASPX
Performance on the web client looks favorableaccept delay or switch to server side processing for large scale requestsJavascript security issues require proxy management
IFRAME
HLA Web Portal - Footprints
SQL ServerFootprint DB(with HTM)
IIS Web Server
Javascript UI manager (state and form control)
Object ParserXML Instance
ASPX + JS
VO Cone SearchVOTable
SOAP STCWeb Services
IFRAME
VOClients
APT
SQL ServerDSS DB(with HTM)
RA,Dec,Radius
Virtual Observatory
Footprints are built on IVOA standard STC XML data model (Space Time Coordinate)
Regions, Convexes, Reference Frames + much much more
Data Access Layer services are built on standard VO protocolsCone SearchSimple Image Access (SIA)
XML across the wire in VOTable or STC formatVO client applications can access HLA footprint programmatic services:
Datascope, Registry, Aladin, GOOGLE?
IVOA note on Footprint Overlay Specification
Database => Performance KeyMicrosoft SQL ServerClient development DOES NOT have to be on WINDOWS
Virtualization tools (Parallels, Remote Desk Top)FreeTDS
SQL scriptsmanage footprint computation of STC table objects/fieldsBuild and populate the different levels of representation
HTM (Hierarchical Triangulated Mesh) integrated for spatial search index
Coordinate based searchingAccessed via stored procedures and user defined functionsBounding circles for each region convex have htm ids
DB Schema STC
•DB Tables map to XML elements in the schema•HLA Science table associates regions to science metadata tags (target, exposure, dataset, filter, PI …)
JHU Spherical Library
Spherical geometry libraryExact equations for highly accurate region definitions, leverages HTMSTC elements are class types (region, convex, halfspace…)C# Assembly (SQL Server dll )
Operations for combining regionsUnions (outlines)Intersections (overlaps)
Mathematical Solutions AreaComplex regions can be made disjoint into convexes
Hierarchical Representations
Exposures (Level 1)Stacks (Level 1 – visualization optimization)Combined sequential exposures (Level 2)Groups (Level 3 & 4)
Mosaics, weight maps, use-defined, custom constrained
Fractals
Performance Issues for crowded overlapsHST unique distribution
sparse ALL-SKY
Exposure Stacks
Many cases where exposures lie on top of each other (form a stack)Can reduce overhead by graphically representing exposures in a stack by a single member exposureDefine stacks using coarse-grained HTM matching for aperture vertices.
Visualization library
C# library with building canvas, frame, scaling and drawing methods using GDIDSS background image access using spherical projection and tiling algorithmsASPX is ~ html with C# class associated.
ASP controls for basic web gui featuresJavascript for interactive mouse and cursor stateEvent handling between the graphics and table paging control for selection
Challenges Ahead
Enhanced capabilities for visualizationCompletion of IVOA standard footprint servicesCommunity exchange of STScI Footprint schemaValidation of footprint representations between existing tools (Starview/APT, HLA, external…)Development of higher level product respresentations (MOSAICS, user-defined…)Storing Region binary blob representations