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scale/offset from variables y and x for GOES-16 netCDF files
Posted: Fri May 05, 2017 4:03 pm
by joleenf
Hi,
Is there a way to get the projection scale_factor and add_offset for x and y in the GOES-16 netCDF files using loadGrid?
Thanks,
Joleen
Re: scale/offset from variables y and x for GOES-16 netCDF files
Posted: Fri May 05, 2017 6:10 pm
by bobc
Hi Joleen -
I looked into this a bit and I wasn't seeing any way of getting at this information. I have forwarded this to a few programmers more familiar with VisAD to see if anything there could help. For example, there may be something buried in the VisAD
GeoGrid class that I haven't been able to find myself. After speaking with a different programmer, we were curious as to why you need to know these values.
I'll follow up with you when I hear back from the programmers.
Thanks -
Bob Carp
Re: scale/offset from variables y and x for GOES-16 netCDF files
Posted: Sat May 06, 2017 2:46 pm
by joleenf
Hi Bob,
I wanted to use a lat/lon, find the fixed grid coordinate, then use a range around that fix grid coordinate for xRange and yRange in loadGrid.
Class GEOSTransformCode: Select all
FGFtoEarth(double fgf_x, double fgf_y, double scale_x, double offset_x, double scale_y, double offset_y)
Transform fractional FGF coordinates to (longitude, latitude).
Code: Select all
earthToFGF(double geographic_lon, double geographic_lat, double scale_x, double offset_x, double scale_y, double offset_y)
Transform Earth coordinates (lon,lat) to fractional FGF coordinates.
Having a quick formula to find out FGFtoEarth and back could be very useful when selecting data regions in scripting.
In addition, I was having problems selecting the display region using the interactive GUI, the only thing I could do was reduce the mage size by stride, and I did not want to stride the data.
Joleen
Re: scale/offset from variables y and x for GOES-16 netCDF files
Posted: Sat May 06, 2017 2:56 pm
by joleenf
Actually, that does not make sense, because the xRange and yRange are row, column indices, not the fixed grid coordinate values.
Pardon my confusion...
Joleen
Re: scale/offset from variables y and x for GOES-16 netCDF files
Posted: Mon May 08, 2017 5:20 pm
by bobc
Thanks for following up, Joleen. Just for clarification, are you no longer needing a way to get at x/y projection scale_factor and add_offset values?
- Bob
Re: scale/offset from variables y and x for GOES-16 netCDF files
Posted: Tue May 09, 2017 2:51 pm
by joleenf
At this moment, no, I do not need to access the scale and offset factors for the x,y coordinates.
Joleen