## scale/offset from variables y and x for GOES-16 netCDF files

Post any questions, ideas, or topics related to Jython and Python scripting.
joleenf
Posts: 1120
Joined: Mon Jan 19, 2009 7:16 pm

### scale/offset from variables y and x for GOES-16 netCDF files

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
bobc
Posts: 939
Joined: Mon Nov 15, 2010 5:57 pm

### Re: scale/offset from variables y and x for GOES-16 netCDF files

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
joleenf
Posts: 1120
Joined: Mon Jan 19, 2009 7:16 pm

### Re: scale/offset from variables y and x for GOES-16 netCDF files

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 GEOSTransform

Code: 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
joleenf
Posts: 1120
Joined: Mon Jan 19, 2009 7:16 pm

### Re: scale/offset from variables y and x for GOES-16 netCDF files

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
bobc
Posts: 939
Joined: Mon Nov 15, 2010 5:57 pm

### Re: scale/offset from variables y and x for GOES-16 netCDF files

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
joleenf
Posts: 1120
Joined: Mon Jan 19, 2009 7:16 pm

### Re: scale/offset from variables y and x for GOES-16 netCDF files

At this moment, no, I do not need to access the scale and offset factors for the x,y coordinates.
Joleen