[gradsusr] convert world coordinate distance to real distance (km)

Jeff Duda jeffduda319 at gmail.com
Sat Nov 5 10:33:43 EDT 2016 

Wendi,
Keep in mind what happens when you alter the geographical bounds in the
control file. Those XDEF/YDEF/ZDEF/TDEF lines control the bounds of your
dimension environment when running grads. Now that you've set the xdef and
ydef to start at 1 and increment by very small values, the maximum x and y
values in your dimension environment are now

max_x = 1 + 319*0.005483962 = 2.749
max_y = 1 + 319*0.00452226 = 2.443

Notice how this math is derived from your control file. This means the
maximum values for lat and lon that won't result in an error are 2.749 and
2.443. You set lat and lon to well outside those ranges in your script,
which is why you are getting the error. You can instead reset lat and lon
so that they're within the bounds above, but I think that's getting away
from the problem you're trying to solve. My understanding is that you want
to plot a field using linear distance coordinates rather than geographical
coordinates. If so, then you don't want to be using lat/lon to set your
dimensions. Use 'set x' and 'set y', and also set your initial value in
your XDEF and YDEF lines to zero so that the lower left corner of your
plots will be at distance coordinate (0,0) and increasing as you go up and
right. Is this what you wanted to do?

Jeff Duda

On Sat, Nov 5, 2016 at 1:35 AM, wendi harjupa <wendiharjupa at gmail.com>
wrote:

> Dear Mr. Jeff
>
> Thank you very much for your advice.
> I have tried it for several times, but it does not work.
> I am very sorry for asking you again.
>
> I got an error as below
> Data Request Warning:  Request is completely outside file limits
> Cannot contour grid - all undefined values
> Error in xcbar.gs: No shading information
>
>
> Here my ctl file and gs file
>
> try.ctl
>
> DSET /TAKAYASU/wendi/xband/G000.grads/KINKI/20150808_0900-
> 1700/data/KINKI00001-20150808-1400-G000-EL000000.bin
> UNDEF -999
>   XDEF 319 LINEAR 1 0.005483962
>   YDEF 319 LINEAR  1 0.00452226
> #  ZDEF  81 LINEAR 125 250
> TDEF   120 LINEAR 09:00Z14JUL1500 60yr
> VARS   1
> rr    81 99 rainfall (mm)
> ENDVARS
>
>
> try.gs
>
>   'reinit'
>    'open /TAKAYASU/wendi/overlay_cappi/try.ctl'
>    'setXrain.gs'
> #   'set mproj off'
> #   'setCOMMON.gs'
>    'set lon 134.9 135.4'
>    'set lat 34 34.5'
>    'd  rr'
>    'xcbar  8.6 8.8 0.8 4 -fw 0.11 -fh 0.15 -edge triangle -fstep 1 -line
> on -lc 1'
>    'set strsiz 0.15 0.15'
>    'draw string 8.5 4.15 mm'
>
> #   'set xaxis 0 10 1'
> #   'set yaxis 0 10 1'
>
>    'close 1'
>
> Thank you very much.
> Best regards,
> wendi
>
>
>
>
>
>
>
> On Thu, Nov 3, 2016 at 1:37 AM, Jeff Duda <jeffduda319 at gmail.com> wrote:
>
>> Wendi,
>> You can always change the text of any control file. There should not be
>> anything stopping you from doing that. Please clarify what you mean.
>>
>> Jeff
>>
>> On Tue, Nov 1, 2016 at 11:53 PM, wendi harjupa <wendiharjupa at gmail.com>
>> wrote:
>>
>>> Dear Mr Jeff
>>>
>>> Thank you very much for your help.
>>>
>>> I have two different types of data set and I need to make composite data
>>> with those data.
>>> One data is mismatch, then I need to know how far the mismatch.
>>>
>>> One of my data set is binary and another one is netCDF.
>>> I can change my control file in my binary data. But, I cannot do this
>>> for my netCDF data.
>>> Would you mind to suggest me, how to change XDEF and YDEF in netCDF data?
>>>
>>> Thank you very much
>>>
>>> best regards,
>>> wendi
>>>
>>> On Wed, Nov 2, 2016 at 12:02 AM, Jeff Duda <jeffduda319 at gmail.com>
>>> wrote:
>>>
>>>> Wendi,
>>>> It sounds like you want to draw a plot with geographic coordinates
>>>> replaced by straight-line/distance coordinates instead. If that is the
>>>> case, one thing you can try is removing the PDEF line from your control
>>>> file and resetting your XDEF and YDEF lines to start at 0 (but keep the
>>>> delta value). That might work. If that doesn't work, you could also try
>>>> turning off the map projection in grads (set mproj off) and then using 'set
>>>> xaxis' and 'set yaxis' in clever ways to make it look like the map you draw
>>>> is in terms of linear distance. Good luck.
>>>>
>>>> Jeff Duda
>>>>
>>>> On Tue, Nov 1, 2016 at 9:32 AM, HARVEY, PHILIP O NH-03 USAF AFMC 412
>>>> OSS/OSW <philip.harvey.1 at us.af.mil> wrote:
>>>>
>>>>> See Ed Williams' Aviation Formulary at http://williams.best.vwh.net/a
>>>>> vform.htm for great circle distance, etc formulas.  The formula you
>>>>> desire is only requires 1 line and can easily be written into a function.
>>>>>
>>>>> Phil
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at grads
>>>>> usr.org] On Behalf Of wendi harjupa
>>>>> Sent: Tuesday, November 01, 2016 2:01 AM
>>>>> To: GrADS Users Forum <gradsusr at gradsusr.org>
>>>>> Subject: [gradsusr] convert world coordinate distance to real distance
>>>>> (km)
>>>>>
>>>>> Dear every one
>>>>>
>>>>> I have problem with converting distance in world coordinate to
>>>>> distance,
>>>>>
>>>>> I have map with
>>>>> lon = 135  135.5
>>>>> lat = 34.5   35
>>>>>
>>>>> I want to set lon =135, as 0 km, and lat=34.5 as 0 km.
>>>>> as we know that 1 deg is about 110 km.
>>>>>
>>>>> Is there any function in grads that can directly convert the world
>>>>> coordinat distance to real distance (km)?
>>>>>
>>>>> Please, any help would be very appreciate.
>>>>>
>>>>> thank you
>>>>> regards,
>>>>> wendi
>>>>>
>>>>> _______________________________________________
>>>>> gradsusr mailing list
>>>>> gradsusr at gradsusr.org
>>>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Jeff Duda
>>>> Post-doctoral research associate
>>>> University of Oklahoma School of Meteorology
>>>>
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>>>>
>>>>
>>>
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>>
>>
>> --
>> Jeff Duda
>> Post-doctoral research associate
>> University of Oklahoma School of Meteorology
>>
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>>
>
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-- 
Jeff Duda
Post-doctoral research associate
University of Oklahoma School of Meteorology
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