[Kst] kst HPIC datasource

[Theodore Kisner]

Hello Everyone,
  I'm starting to work on integrating support for displaying healpix pixelized 
maps in kst.  As my previous email suggests, this currently requires defining 
"yet another kind of plot object" which is analogous to Curves or Images and 
which Kst2DPlot will keep a list of.  Of course, a future refactoring may 
make this process more generalized...

Regardless of future work on the actual plotting, I can at least implement a 
datasource for reading healpix-format files.

Background
-----------
Healpix is a method of pixelizing the sphere such that all the pixels have 
equal area and lie on iso-latitude rings.  It is often used in CMB research 
to represent maps of the sky.  These maps are stored in FITS files in a very 
specific format.

HPIC
-----
HPIC is my GPL'd implementation of the healpix algorithm.  It is a C library 
that allows the user to read/write/test healpix FITS files, project the 
spherical data onto a rectangular grid (for display purposes), and perform 
other simple operations.  The latest version (0.49) is available here:

http://cmb.phys.cwru.edu/hpic/

There are 2 scenarios I can think of where kst might be used with HPIC.  The 
first is to display static map data contained in a FITS file.  The second is 
to do real-time "binning" of map data as it is being acquired.  I will only be 
addressing the first case initially.  I imagine the second case could be 
handled by a plugin that reads vectors representing DATA / RA / DEC / polar 
angle and outputs a map vector.

Patches
--------
Attached you will find a patch set that should apply (in order) to HEAD.  Here 
is a brief description of each patch:

1:  Lays out the skeleton datasource directory.  Adds configure checks for 
hpic library.

2:  Couple of overlooked lines in configure.in.in/Makefile.am.  Datasource can 
now detect supported files.  readField doesn't return anything yet.  Note 
that the function "understands_hpic" currently returns a value of 100 for 
supported files.  This is necessary because the LFIIO datasource is greedy and 
claims to support *all* valid FITS files with a weight of 99.

3:  Datasource now reads the names / units from the file and uses them for the 
field names.  If the table columns have no names, it uses a default string.

4:  The _metaData Qmap now contains map information (NSIDE, ordering, etc), as 
well as any optional keywords found in the FITS file.  Eventually, my hope is 
to access this metadata from a "plotsource" that inherits from KstDataObject.  
I think this is possible, since I can dereference (approximately):

KstDataObject->KstVectorMap->KstRVector->provider->metadata  

readField now returns a full-sphere map vector.  I think the HPIC datasource 
is almost functionally complete!  Now to move on to plotting ;-)

cheers,

-Ted





   

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