[ncl-talk] Pixel to Lat/Lon

[Mary Haley]

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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