Helioviewer JP2 XML Tags
From Helioviewer Wiki
The JPEG 2000 standard allows for an XML box at the top of the file. The Helioviewer Project fills this box with two main classes of XML tags; the original FITS header tags rendered as XML element-content pairs, and XML information written by the Helioviewer Project. The XML box looks like this:
<?xml version="1.0" encoding="UTF-8" ?> <meta> <fits> ...original FITS keywords as XML elements... ...extra keywords inserted by the Helioviewer Project... </fits> </meta>
For example, the FITS keyword CDELT1 = 1.630000 is converted to
<CDELT1>1.630000</CDELT1>
and the FITS keywords FILEORIG = 011123_200876.img, CUNIT1 = ARCSEC (strings) as
<FILEORIG>011123_200876.img</FILEORIG> <CUNIT1>ARCSEC</CUNIT1>
Click here for the latest list of data-sets explicitly supported by the Helioviewer Project.
XML tags written by the Helioviewer Project
These XML elements are written by the Helioviewer Project. They describe extra information concerning the creation of the JP2 files, and they all begin HV_. If you suspect that extra elements are required, then please let us know as soon as possible.
| tag | meaning | default value |
|---|---|---|
| HV_ROTATION | the rotation about the centre of the image applied to the original FITS data, to get the resultant JP2 image. The rotation always ensures that the rotation axis of the Sun is parallel to the y-axis of the image. | 0.0 |
| HV_JP2GEN_VERSION | The JP2 file version. | 0.6 |
| HV_JP2GEN_BRANCH_REVISION | The Bazaar branch revision number of JP2Gen that wrote this JP2 file. | 49 (19 Nov 2009) [Branch revision 48 (HV_JP2GEN_VERSION =0.6) and higher can also sometimes include the date and time of when the file was written.] |
| HV_HVS_DETAILS_FILENAME | The IDL file that contains metadata - details - of the device and its measurements, and the choices made in the JP2 encoding. | $HV_JP2GEN/<nickname>/hvs_default_<nickname>.pro |
| HV_HVS_DETAILS_FILENAME_VERSION | The version number of the details file. | Depends on the file. |
| HV_COMMENT | A comment on which program wrote the file, where the file was written, and whom to contact with any questions concerning this file. | Depends on the contents file HV_WRITTENBY.PRO (part of the JP2GEN suite) at the site where the file was created. |
| HV_SUPPORTED | Is this particular OBSERVATORY-INSTRUMENT-DETECTOR-MEASUREMENT explicitly supported by this version of JP2GEN? | TRUE / FALSE |
| HV_QUICKLOOK | Was quicklook data was used to create the JP2 file? | TRUE / FALSE. |
| HV_ROCC_INNER [coronagraphic data only] | Radius of the inner occulting disc in coronagraphic data. | Only applies to coronagraphic data, and varies per coronagraph. |
| HV_ROCC_OUTER [coronagraphic data only] | Radius of the outer field of view in coronagraphic data. | Only applies to coronagraphic data, and varies per coronagraph. |
| HV_ERROR_REPORT [optional] | Reports on any errors found in converting FITS files to JP2 files, and the corrective action taken. Most commonly used to report the replacement of missing quantities in the original FITS files that are required by the Helioviewer Project i.e., pixel sizes in arcseconds. | Optionally present depending on the presence of an error. |
