Lessons learnt with Aladin and characterization experience for
SIA2.0F.Bonnarel, CDS
(credit to Aladin developpers, CADC,ECF,ESAC, ESO VO people,
DAL and DM IVOA WG)
SIA 1.0 (2002 !!!)
• Pros:– Solved the availabilty issue in a standard way for the first time.– Gave some rather unformal description/characterization of the
images
• Limitations: – No mapping on datamodel – Ad hoc UCDS and no utypes– No structuration of the query response. – No staging
Query phase: extended ROI
• Extend ROI requests to all or a significant subset of stc AstroCoordArea– Use case: Draw a contour on top of a
Preview or a wide field image and use
it as a ROI.– Trick : drawn contours are on the image plane
How to translate that in string stc in some given coordinate system….
SIA 2.0 Query interface: SSA 1.0 + ???
• Requests by more characterization utypes (sampling in combination with resolution)
• More request by ranges (resolution and sampling)
• Add query by Observation/characterization utypes using « utype Extended » ADQL as it is proposed for TAP (non redondant with parameter= value for level 3 or 4
queries)?
Query response: extended datamodel usage
• Use of Curation, Target, DatasetID and Characterization as in SSA.
• Extend SSA Characterization package towards full level 2 for resolutions and sampling for spatial and additional sampled axes ( spectral or whatever)
• Level 3 and Level 4 maybe available through DAL Extension mechanism (described in SSA):– Level 3 example : footprint description– Level 4 = PSF described as a link to a PSF service (eg
TERAPIX qualityfits ) JPEG visualized in Aladin– Level 4 = Filter transmission curve available in Aladin
Query response: Dataset linkage
• Provenance:– instrumental (heavy stuff in FITS keywords)– Processing ( calibration --- links to unprocessed data, ancillary
data)• Access and views of complex or heterogeneous data (Linkage
model) – Linkage to some simple derived datasets or excerpts of the
main dataset (heterogeneous DAL protocols, generic dataset discovery)
• Parallel development of a provenance or dataset linkage datamodel by DM WG
Staging/Asynchronous access
• Individual images may need heavy statistical processing (Bayesian fusion, Markov multispectral segmentation)
– as eg CDS/LSIIT collaboration has shown.
• Extremly faint source detection
• Image cleaning from cosmics …
• Nice to get staging facility to access results later from another aladin session replaying the original images sequences for comparison…
– Idea: original query response give acref to process follow up page,
– replaced by standard DAL (image, spectrum, table) query response when processing is completed
– Interface has only to keep track of original acref ….