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HOME ART > Tutorial > Doing More > DB Populating
Data Loader Configuration for IMAGEs



 The Saada loader recognizes IMAGE as FITS files with at least one extension of IMAGE type. All primary header keywords will be loaded in addition with those of the selected IMAGE extension. Image astrometry is solved by using standard WCS keywords. Saada does not store the bitmap into the DB but just keywords values.

 Extension Selection : By default Saada considers the first IMAGE extension as the image to load. The field Extension to Load can nevertheless specify wich extension must be loaded. This extension must be given either by number (e.g. #1) or by name. The selected extension can be drag and dropped from the data sample window.

Extension Selection

If a data file doesn’t have the requested extension, an error is raised and the loading process is halted.

 The image configuration is similar to MISC configuration (see) added with position considerations.

Image Configuration Parameter

 About Priority : All parameters specific to images have a priority selector. The function of the mapping priority is always the same whatever the parameter is :

  • No Mapping : The mapping rule given in the configuration is never used.
  • Last : The mapping rule given in the configuration is only used when Saada doesn’t manage to do it automatically. Taking the position example, in last priority mode, Saada will first try to find out position keywords by its own. If it fails, mapping rule will then be used (either keywords or constant values).
  • First : The mapping rule given in the configuration is first applied. In case of failure, Saada will try to find out the good parameters automatically. Taking the position example again, if the configuration says that the position is given by keywords POS_RA and POS_DEC and if these keywords do not exist in the product file, Saada will then try to find out other position keywords automatically.
  • Only : The mapping rule given in the configuration is applied without possibility of automatic detection.

Inside Saada page explains how does automatic parameter detection work.

 Coordinate System : Indicates how to determine the coordinate system of the input data. The system can either be given as keyword (e.g. SYSTEM, EQUINOX) or as quoted values (e.g. ‘FK5,J2000’). When this parameter is used (see priority), all products loaded with the configuration are assumed to use this system.

 Position : Indicates how to determine the coordinates of the input data. Coordinates are considered as the image center. They can either be given as keyword names (e.g. RA2000, DEC2000) or as quoted values (e.g. ‘M33’ or ’12:34:4.7 -10:20:30.5’ or ’12.56 +43.34).

 Position Errors : Indicates how to determine the error on coordinates. Errors can be set with 1, 2 or 3 parameter :

  • One parameter : The error is supposed a circle with a radius given by this unique parameter.
  • Two parameters : The error is supposed to be an ellipse. The first parameter gives the error along of the longitude axis, while the second parameter gives the error along of the latitude axis.
  • Three parameters : The error is supposed to be an oriented ellipse The first parameter gives the major axis of the ellipse, the second parameter gives the minor axis and the third gives the angle expressed in degree. The error can be given as keyword(s) (e.g. RA_ERR, DEC_ERR or as quoted value(s) (‘12.7,34.5,23’).
  • Units : The error mapping inludes units. Error unit is always given by values but never by keyword content.

The Saada data loader uses coordinate parameters to compute coordinates with associated errors. Coordinates values at collection level are converted from the original system to the SaadaDB system (set at SaadaDB creation time). Units are converted from the original units to degree. When collection level coordinates can not be set, data are regardless loaded but coordinates are not set.

last update 2008-05-13