[GRASS-user] Polar projection

Fri Jan 1 09:12:13 PST 2021

Hi Jón,

I work regularly in EPSG:3413, but the same issue applies. "d.grid -g 1:0" doesn't make a grid to the pole. Does it for you? I'd like to submit a bug report as per the suggestion from Markus, but am not sure what the bug is if this command works for you when the pole is included in the view.

  -k.

On 2020-12-31 at 09:23 -08, Jón Eiríksson <jeir at hi.is> wrote...
> This has worked for me:
>
> (Thu Dec 31 17:22:11 2020)
> g.proj -p
> -PROJ_INFO-------------------------------------------------
> name       : Stereographic
> proj       : stere
> datum      : wgs84
> ellps      : wgs84
> lat_0      : 90
> lat_ts     : 70
> lon_0      : -45
> k          : 1
> x_0        : 0
> y_0        : 0
> no_defs    : defined
> towgs84    : 0.000,0.000,0.000
> -PROJ_EPSG-------------------------------------------------
> epsg       : 3413
> -PROJ_UNITS------------------------------------------------
> unit       : meter
> units      : meters
> meters     : 1
> (Thu Dec 31 17:22:11 2020) Command finished (0 sec)
>
> Jon
>
>
>
>
> On 31 Dec 2020, at 16:26, Markus Neteler wrote:
>
>> Hi Ken,
>>
>> On Thu, Dec 31, 2020 at 3:06 AM Ken Mankoff <mankoff at gmail.com> wrote:
>>>
>>> Dear GRASS List,
>>>
>>> Can someone suggest what setup to use (EPSG code? proj4 code?) to
>>> have the projection centered on the N. pole? I'm looking to create
>>> a graphic similar to this image in the Raster Gallery: 
>>> https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgrass.osgeo.org%2F%2Fimages%2Fgallery%2Fraster%2Fday_on_earth_N.png&data=04%7C01%7Cjeir%40hi.is%7Cc4ce599d0faf40d3408608d8ada8dff2%7C09fa5f0e211846568529677ed8fdbe78%7C0%7C0%7C637450288118244590%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=1b0EG%2B%2ByT0LjNGOp55l%2FwYiVKSNfAeUvd%2BZS12dCWZg%3D&reserved=0
>>>
>>> If I set up a polar projection based on
>>> https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fspatialreference.org%2Fref%2Fsr-org%2F8243%2F&data=04%7C01%7Cjeir%40hi.is%7Cc4ce599d0faf40d3408608d8ada8dff2%7C09fa5f0e211846568529677ed8fdbe78%7C0%7C0%7C637450288118244590%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=I7u9KAIJ0geqmtTPZv1vUg3kiAtqtASajvhxzCwFmy4%3D&reserved=0 
>>> using:
>>>
>>> grass -c ./G
>>> g.proj -c proj4="+proj=stere +lat_0=90 +lat_ts=45 +lon_0=-170 +k=1
>>> +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs"
>>>
>>> Things mostly work, but
>>>
>>> d.grid -g 1:0 color=red
>>>
>>> does not show latitude lines on most of the graphic (see attached).
>>
>> I managed to generate it with
>>
>> Preparation of a 10 degree grid:
>>
>> # EPSG:4326
>> GRASS :~ > g.region -dp
>> projection: 3 (Latitude-Longitude)
>> zone:       0
>> datum:      wgs84
>> ellipsoid:  wgs84
>> north:      90N
>> south:      90S
>> west:       180W
>> east:       180E
>> nsres:      1
>> ewres:      1
>> rows:       180
>> cols:       360
>> cells:      64800
>> GRASS :~ > v.mkgrid grid=36,18 map=grid_10deg
>> # download "Natural Earth I with Shaded Relief, Water, and Drainages"
>> from
>> https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.naturalearthdata.com%2Fdownloads%2F10m-raster-data%2F10m-natural-earth-1%2F&data=04%7C01%7Cjeir%40hi.is%7Cc4ce599d0faf40d3408608d8ada8dff2%7C09fa5f0e211846568529677ed8fdbe78%7C0%7C0%7C637450288118244590%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=at%2BPzc3vGV%2FmxVhg%2BxltDODIC52rrl%2Bd39ZTtta7uDA%3D&reserved=0
>> GRASS :~ > r.import in=NE1_HR_LC_SR_W_DR.tif
>> output=natural_earth_global_landcover
>> GRASS :~ > g.region raster=natural_earth_global_landcover.1
>> GRASS :~ > r.composite r=natural_earth_global_landcover.1
>> g=natural_earth_global_landcover.2 b=natural_earth_global_landcover.3
>> out=natural_earth_global_landcover.rgb
>> GRASS :~ > exit
>>
>> # WGS 84 / Arctic Polar Stereographic
>> https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fepsg.io%2F3995&data=04%7C01%7Cjeir%40hi.is%7Cc4ce599d0faf40d3408608d8ada8dff2%7C09fa5f0e211846568529677ed8fdbe78%7C0%7C0%7C637450288118244590%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=JwnkjczUnnrbi%2F%2BnQGepiYo4eB02S5%2BQUWSMK3rRFDs%3D&reserved=0
>> grass78 -c epsg:3995 ~/grassdata/arctic_polar_stereographic
>> GRASS :~ > g.proj -w
>> PROJCS["WGS 84 / Arctic Polar Stereographic",
>>     GEOGCS["WGS 84",
>>         DATUM["WGS_1984",
>>             SPHEROID["WGS 84",6378137,298.257223563,
>>                 AUTHORITY["EPSG","7030"]],
>>             AUTHORITY["EPSG","6326"]],
>>         PRIMEM["Greenwich",0,
>>             AUTHORITY["EPSG","8901"]],
>>         UNIT["degree",0.0174532925199433,
>>             AUTHORITY["EPSG","9122"]],
>>         AUTHORITY["EPSG","4326"]],
>>     PROJECTION["Polar_Stereographic"],
>>     PARAMETER["latitude_of_origin",71],
>>     PARAMETER["central_meridian",0],
>>     PARAMETER["false_easting",0],
>>     PARAMETER["false_northing",0],
>>     UNIT["metre",1,
>>         AUTHORITY["EPSG","9001"]],
>>     AXIS["Easting",SOUTH],
>>     AXIS["Northing",SOUTH],
>>     AUTHORITY["EPSG","3995"]]
>>
>> GRASS :~ > g.region n=2930000 s=-2500000 w=-4250000 e=4310000
>> nsres=10000 ewres=10000 -p
>> GRASS :~ > v.proj location=latlong_wgs84 mapset=PERMANENT
>> input=grid_10deg
>> GRASS :~ > r.proj location=latlong_wgs84 mapset=PERMANENT
>> input=natural_earth_global_landcover.rgb
>> GRASS :~ > d.mon wx0
>> GRASS :~ > d.rast natural_earth_global_landcover.rgb
>> GRASS :~ > d.vect grid_10deg type=boundary
>>
>> The resulting map looks as attached (hope I didn't forget to copy a
>> command here).
>> Indeed, d.grid doesn't looks as expected
>>
>> GRASS :~ > d.grid 10 -w
>> .. is incomplete. Worth a bug report, IMO.
>>
>> Cheers,
>> Markus
>>
>> -- Markus Neteler, PhD
>> https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.mundialis.de%2F&data=04%7C01%7Cjeir%40hi.is%7Cc4ce599d0faf40d3408608d8ada8dff2%7C09fa5f0e211846568529677ed8fdbe78%7C0%7C0%7C637450288118244590%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=R0%2BkMUwS4HSEjqNltZIopTVnEv7c%2FUSCfKjrHT%2BWOIE%3D&reserved=0
>> - free data with free software
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>> https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcourses.neteler.org%2Fblog&data=04%7C01%7Cjeir%40hi.is%7Cc4ce599d0faf40d3408608d8ada8dff2%7C09fa5f0e211846568529677ed8fdbe78%7C0%7C0%7C637450288118254587%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=JB5zKZRxku4818pqUJirSvMG3lyrA%2Bx50LLUBzVxkyU%3D&reserved=0
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