On 3/7/2012 7:53 PM, ghansham sangar wrote:
R/Sir
With the reference to this link:
http://www.unidata.ucar.edu/mailing_lists/archives/cf-satellite/2011/msg00069.html
I have pasted the contents of the link here
Re: [cf-satellite] Query related to CF conventions
* /To/: cf-satellite@xxxxxxxxxxxxxxxx
<mailto:cf-satellite@DOMAIN.HIDDEN>
* /Subject/: Re: [cf-satellite] Query related to CF conventions
* /From/: John Caron <caron@xxxxxxxxxxxxxxxx
<mailto:caron@DOMAIN.HIDDEN>>
* /Date/: Fri, 29 Jul 2011 06:40:45 -0600
On 7/28/2011 10:32 PM, ghansham sangar wrote:
R/Sir
I have an issue related to CF conventions 2D coordinate variables
(I mean lat/lon arrays corresponding to satellite images) I have
been able to handle the case where lat/lon arrays have one to one
correspondence with satellite imagery pixels.
But if we have some scaling like:
1. Image Data ( 5600* 5600)
Lat/Lon Arrays (1400*1400) each
Or I have the other ways
2. Image Data(1400x1400)
Lat/Lon Arrays (2800*2800).
How to indicate that in the image pixel should refer to which
Lat/Lon array pixel. Like in first case every four pixels of image
correspond to 1 lat/lon array pixel.
I am using HDF 4 for writing products.
I have tried to search on internet. It says something about
dimscale. But I am not aware what exactly to do.
regards
Ghansham
_______________________________________________
cf-satellite mailing list
cf-satellite@xxxxxxxxxxxxxxxx
For list information or to unsubscribe, visit:
http://www.unidata.ucar.edu/mailing_lists/
HI Ghansham:
1. I understand that HDF-EOS has a convention for your situation. Are
you using that? Could you explain how it works?2. CF uses netCDF as
its file format. HDF4 lacks shared dimensions, so is not an complete
fit to the CF model. Why are you writing in HDF4?
John
I am not using HDF-EOS.
I am sorry in the last mail, I mentioned it was HDF-4. But as in the
coming time we plan to generate most of the data products in HDF-5.
Is it now possible in HDF-5 context?
HDF-5 has dimension scale feature.
I also read that HDF-5 dimension scale is not exactly what is netcdf
shared dimension.
But now I want to know is there a way in which we can accommodate such
datasets in HDF-5.
I mean to say can we have a 2-D coordinate variable (as stated in the
previous mail) in HDF-5:
Image Data (5600*5600)
Lat Array (1400*1400), Lon Array (1400*1400)
OR
Image Data (1400*1400)
Lat Array (2800*2800), Lon Array (2800*2800)
regards
Ghansham
HDF5 has dimension scales, but they are not the same as shared
dimensions (close, no cigar).
You want to use netCDF4 for this. It writes HDF5 files, with a kludge, I
mean workaround, for shared dimensions.
John
