[ncl-talk] Pixel to Lat/Lon

[Ipsita Putatunda]

Hi Mary,
 I have uploaded my data file with my scripts through ftp.

Ipsita

On Fri, Jul 14, 2017 at 2:51 AM, Dennis Shea <shea at ucar.edu> wrote:

> IMHO: The script is working correctly. However, there is a mismatch
> between the
> the user's VERY high resolution (0.15 degrees) 'target grid' and the
> resolution of the swath data points.
>
> re:
>
>  nlat=1200
>  nlon=2400
>
> defines a grid with spacing 0.15 degrees. VERY high resolution
>
> ====
>
> I have no idea what the rationale for the '400' used for GBIN and GKNTwas
> based upon.
>
>  GBIN  = new ( (/400,nlon/), float )
>  GKNT = new ( (/400,nlon/), integer )
>
> =====
>
> The binning algorithm looks at each swath lat/lon location. It finds the
> target grid box that 'surrounds'  the current swath lat/lon location.
>
> If there are target grid boxes which do not surround the swath grid poins,
> then they are returned as missing (_FillValue). Hence, the 'fractured' look
> of the plot.
>
> D
>
>
>
>
>
> On Thu, Jul 13, 2017 at 2:52 PM, Mary Haley <haley at ucar.edu> wrote:
>
>> Hi Ipsita,
>>
>> I'm not sure what you mean by " even though the plot is not coming with
>> a clear contours. "
>>
>> The plot you included doesn't look particularly wrong, so can you explain
>> what you were expecting?
>>
>> The script you attached does not include any plotting code, so I can't
>> help you much there.
>>
>> Can you be more specific about the problem?  Also, it would really help
>> if you can provide the data and the plotting script in the usual way (ftp).
>>
>> Thanks,
>>
>> --Mary
>>
>>
>>
>>
>> On Thu, Jul 13, 2017 at 7:04 AM, Ipsita Putatunda <
>> ipsita.putatunda at gmail.com> wrote:
>>
>>> Thank you Dave for your suggestions. I tried to plot the data, but it is
>>> coming only if I plot setting resource "RasterFill", and even though the
>>> plot is not coming with a clear contours. Don't know where I am making
>>> mistake. I tried to regrid the data using "triple2grid" but then all the
>>> values are coming undefined. I am attaching herewith my script and the
>>> figure I have got after plotting. Any help will be appreciated.
>>> Thanks in advance.
>>>
>>> Ipsita
>>>
>>>
>>> On Thu, Jul 13, 2017 at 4:19 AM, Dave Allured - NOAA Affiliate <
>>> dave.allured at noaa.gov> wrote:
>>>
>>>> Ipsita,
>>>>
>>>> This HDF5 file has coordinate arrays Colatitude and Longitude.  The
>>>> units of each are degrees, not pixels.  However, please notice two
>>>> anomalies:
>>>>
>>>> 1.  The coordinates are packed with an unusual scale/offset packing
>>>> scheme.  The packing parameters are in attributes Scale_Factor and
>>>> Add_Offset, which are not CF standard attributes.  However, the intent is
>>>> fairly clear.  To unpack each coordinate value, just multiply by the
>>>> Scale_Factor.
>>>>
>>>> The Add_Offset's are zero in this case, and can therefore be ignored.
>>>> That is good, so that we do not have to worry about whether the offset
>>>> would be applied before or after the scale factor.
>>>>
>>>> This will produce colatitudes in the normal range 60 to 120 degrees,
>>>> and longitudes in the normal range 0 to 360 degrees.
>>>>
>>>> 2.  I assume that the colatitudes conform to the current definition on
>>>> Wikipedia.  You might confirm this with the data provider, if you wish.
>>>> This definition is the number of degrees southward from the north pole.
>>>> The colatitude values unpacked are in the range 60 to 120 degrees, which
>>>> translate to 30 north to 30 south in normal latitude units.
>>>>
>>>> --Dave
>>>>
>>>>
>>>> On Wed, Jul 12, 2017 at 12:08 AM, Ipsita Putatunda <
>>>> ipsita.putatunda at gmail.com> wrote:
>>>>
>>>>> The Latitude (here Colatitude) and Longitude data are in pixels which
>>>>> is -30 to 30 degree and 0 to 360 degree. Please find the file I am
>>>>> attaching herewith.
>>>>>
>>>>> Ipsita
>>>>>
>>>>> On Tue, Jul 11, 2017 at 10:30 PM, Dave Allured - NOAA Affiliate <
>>>>> dave.allured at noaa.gov> wrote:
>>>>>
>>>>>> Ipsita,
>>>>>>
>>>>>> How is your input data georeferenced?  Does the input file include
>>>>>> coordinate variables?  That is the most common way to get lats and lons for
>>>>>> individual pixels.
>>>>>>
>>>>>> --Dave
>>>>>> (Please reply to the mailing list.)
>>>>>>
>>>>>>
>>>>>> On Tue, Jul 11, 2017 at 12:22 AM, Ipsita Putatunda <
>>>>>> ipsita.putatunda at gmail.com> wrote:
>>>>>>
>>>>>>> Dear NCL users,
>>>>>>>   I need help in converting pixels to Lat/Lon grid. Is there any
>>>>>>> function or way in ncl for doing this operation? Please suggest.
>>>>>>>
>>>>>>> Thanks in advance,
>>>>>>> Ipsita
>>>>>>>
>>>>>>
>>>
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