Re: grdcut: Error cutting over +/-180° longitude

Dear Paul,

Thank you for your explanation of the correct -R usage. I wasn't aware of the west < east requirement and the proper solution. 

May I suggest that you write 

"grdcut: Make sure west < east for geographic coordinates"

in the error message? While your version is technically correct, I find mine easier to comprehend: west is "left" and east is "right". 

On -R[...]r: I tried the "r" to reduce the size of the cut terrain as a Lambert conic conformal projection, due to its nature, "wastes" quite a lot of the cut area outside the plotted area. Think of the wasted cake when you use a rectangular shaped cookie cutter (my resulting plot) on a wedge of cake (my cut terrain). As pointed out by you it doesn't work, and as it didn't cause any trouble, I forgot about it and it stayed. 

Thank you again and all the best,
Kristof

> Am 23.03.2014 um 22:00 schrieb Paul Wessel <[email protected]>:
> 
> I've improved the error message to say (for geographic grids):
> 
> grdcut: Error: grid x range <= 0.0
> grdcut: Make sure east > west for geographic coordinates
> 
> I should also add that your -R75/17/-124/79r is the same as -R75/-124/17/79 which of course also would fail badly.  So either use
> 
> -R75/17/236/79r or -R75/236/17/79 or even -R-285/17/-124/79r
> 
> -p
> 
>> On Mar 23, 2014, at 10:40 AM, Paul Wessel <[email protected]> wrote:
>> 
>> Usually, one has to ensure that west < east, even if picking corners, so the -124 is causing trouble.  It works better with 236 since 236 > 5 while -124 < 5.
>> 
>> -p
>> 
>>>> On Mar 23, 2014, at 9:03 AM, Kristof Koch <[email protected]> wrote:
>>> 
>>> Dear Paul,
>>> 
>>> I'd say so:
>>> 
>>> $ grdinfo ETOPO1_Ice_g_gmt4.grdETOPO1_Ice_g_gmt4.grd: Title: ETOPO1_Ice_g_gmt4.grd
>>> ETOPO1_Ice_g_gmt4.grd: Command:
>>> ETOPO1_Ice_g_gmt4.grd: Remark:
>>> ETOPO1_Ice_g_gmt4.grd: Gridline node registration used [Geographic grid]
>>> ETOPO1_Ice_g_gmt4.grd: Grid file format: ni = GMT netCDF format (32-bit integer), COARDS, CF-1.5
>>> ETOPO1_Ice_g_gmt4.grd: x_min: -180 x_max: 180 x_inc: 0.0166666666667 name: Longitude [degrees_east] nx: 21601
>>> ETOPO1_Ice_g_gmt4.grd: y_min: -90 y_max: 90 y_inc: 0.0166666666667 name: Latitude [degrees_north] ny: 10801
>>> ETOPO1_Ice_g_gmt4.grd: z_min: -10898 z_max: 8271 name: z
>>> ETOPO1_Ice_g_gmt4.grd: scale_factor: 1 add_offset: 0
>>> ETOPO1_Ice_g_gmt4.grd: format: classic
>>> 
>>> The Version of GMT I'm using is 5.1.1_r12890 [64-bit] on Ubuntu 12.04.4 LTS (GNU/Linux 2.6.32-042stab084.17 x86_64)
>>> 
>>>>> Am 23.03.2014 um 19:52 schrieb Paul Wessel <[email protected]>:
>>>> 
>>>> Does grdinfo say your etopo1 grid is geographic?  If not you will have to add -fg.
>>>> 
>>>> Sent from my iPad
>>>> 
>>>>> On Mar 23, 2014, at 12:31 AM, Kristof Koch <[email protected]> wrote:
>>>>> 
>>>>> Dear List,
>>>>> 
>>>>> I'm trying to cut the ETOPO1 grid. My script works as desired as long as -R doesn't span over +/-180° longitude, however I get the following error trying to cut over +/-180° longitude:
>>>>> 
>>>>> grdcut: Error: grid x range <= 0.0
>>>>> grdcut (GMT_grdcut): Unacceptable PLOT_DEGREE_FORMAT template. A not allowed [/tmp/apollodor-8GOUnDRc/tmp_elevation_data_raw.grd]
>>>>> 
>>>>> the relevant snippet of code:
>>>>> 
>>>>>    TERRAIN_BOUNDARIES=75/17/-124/79
>>>>> 
>>>>> grdcut \
>>>>>    ETOPO1_Ice_g_gmt4.grd \
>>>>>    -G"${WORK_DIR}"/tmp_elevation_data_raw.grd \
>>>>>    -R"${TERRAIN_BOUNDARIES}"r
>>>>> 
>>>>> After studying the grdcut manpage, I'm not quite sure how to make it work. Any hints are welcome.
>>>>> 
>>>>> All the best,
>>>>> Kristof Koch
>>>>> 
>>>>> --
>>>>> My PGP Public Key: http://kristofkoch.de/pgp/
>>>>> 
>>>>> 
>>>>> To unsubscribe, send the message "signoff gmt-help" to [email protected]
>>>> 
>>>> To unsubscribe, send the message "signoff gmt-help" to [email protected]
>>> 
>>> 
>>> --
>>> My PGP Public Key: http://kristofkoch.de/pgp/
>>> 
>>> 
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> 
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