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This document provides information on the LOFAR Sky Image Cubes, which are a hierarchical format for Lofar image data. It includes details on the current image structure, the standard imaging pipeline, and the Python modules used for data conversion. The document also discusses the issues related to pipeline concerns and data interface concerns, such as write speed and data access speed.
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Lofar Sky Image Cubes LOFAR-USG-ICD-004 V 2.00.00 K.R.Anderson Universiteit van Amsterdam 9.9.2010
LOFAR SKY IMAGE CUBES • Lofar image data • Nominal observation • 248 subbands • 1 image per subband • Natural for a hierarchical format • Other LOFAR observation modes work per subband. • Effort toward parallel hierachical structure across LOFAR observation types.
LOFAR SKY IMAGE CUBES • Current ICD Sky Image Structure
LOFAR SKY IMAGE CUBES • The Image Group
LOFAR SKY IMAGE CUBES • Currently, Standard Imaging Pipeline (sip) works on Measurement Set format data • Renders one casa image per subband • Add-on, Python module (skim.py), converts to HDF5 LOFAR ICD format, w/ PyTables • Eventually, the LOFAR DAL (Data Access Library) will do the work. • Python DAL wrapper (pydal) will provide scriptable interface for read/write of LOFAR data products.
LOFAR SKY IMAGE CUBES • Issues of pipeline concern • Write speed • Pytables very heavy weight • Not needed for data writing • H5.py a light weight option at the python layer • Issues of data interface concern • Data access speed • Slicing, extracting, etc.