[GRASS-dev] [GRASS GIS] #1372: Different lat-lon grid size for geographic grids

#1372: Different lat-lon grid size for geographic grids
--------------------------------+-------------------------------------------
Reporter: alf | Owner: grass-dev@…
     Type: enhancement | Status: new
Priority: normal | Milestone:
Component: Projections/Datums | Version: svn-develbranch6
Keywords: | Platform: All
      Cpu: Unspecified |
--------------------------------+-------------------------------------------
When setting locations at high latitudes, the meridians / parallels
spacing ratio tend to be small. Find attached an example of a lcc grid
with projection at high lats (lcc_geogrid.png).

In order to have a better output we could introduce parameters for
optional separate ew and ns (geo)grid sizing.

Also it will be important to set a minimum/maximum for grid drawing, so we
can avoid cluttering the maps as soon as meridians become too dense (e.g.
in polar areas).

Alessandro Frigeri

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Ticket URL: <http://trac.osgeo.org/grass/ticket/1372&gt;
GRASS GIS <http://grass.osgeo.org>

#1372: Different lat-lon grid size for geographic grids
--------------------------------+-------------------------------------------
Reporter: alf | Owner: grass-dev@…
     Type: enhancement | Status: new
Priority: normal | Milestone:
Component: Projections/Datums | Version: svn-develbranch6
Keywords: d.grid | Platform: All
      Cpu: Unspecified |
--------------------------------+-------------------------------------------
Changes (by hamish):

  * keywords: => d.grid

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Ticket URL: <https://trac.osgeo.org/grass/ticket/1372#comment:1&gt;
GRASS GIS <http://grass.osgeo.org>

#1372: Different lat-lon grid size for geographic grids
-------------------------+--------------------------------------------------
Reporter: alf | Owner: grass-dev@…
     Type: enhancement | Status: new
Priority: normal | Milestone: 6.5.0
Component: Display | Version: svn-develbranch6
Keywords: d.grid | Platform: All
      Cpu: Unspecified |
-------------------------+--------------------------------------------------
Changes (by hamish):

  * component: Projections/Datums => Display
  * milestone: => 6.5.0

Comment:

work around: run d.grid at the desired longitude spacing, and then again
with the grid size set to the latitudes you want grid lines at.

so for your example:
{{{
d.grid -g size=2
d.grid -g size=86:12
d.grid -g size=86:18
}}}

Hamish

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Ticket URL: <https://trac.osgeo.org/grass/ticket/1372#comment:2&gt;
GRASS GIS <http://grass.osgeo.org>

#1372: Different lat-lon grid size for geographic grids
-------------------------+--------------------------------------------------
Reporter: alf | Owner: grass-dev@…
     Type: enhancement | Status: new
Priority: normal | Milestone: 6.5.0
Component: Display | Version: svn-develbranch6
Keywords: d.grid | Platform: All
      Cpu: Unspecified |
-------------------------+--------------------------------------------------

Comment(by hamish):

btw, I just fixed d.grid + geogrid longitude label placement in all
branches for meridians which deviated to grid-north by many degrees (e.g.
zoomed-out LCC projections).

Hamish

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Ticket URL: <https://trac.osgeo.org/grass/ticket/1372#comment:3&gt;
GRASS GIS <http://grass.osgeo.org>

#1372: Different lat-lon grid size for geographic grids
-------------------------+--------------------------------------------------
Reporter: alf | Owner: grass-dev@…
     Type: enhancement | Status: new
Priority: normal | Milestone: 6.5.0
Component: Display | Version: svn-develbranch6
Keywords: d.grid | Platform: All
      Cpu: Unspecified |
-------------------------+--------------------------------------------------

Comment(by hamish):

new direction= option added in devbr6 r57699 to allow only drawing east-
west or north-south grid lines. run the module twice with two different
size intervals to get the custom effect. I'll try to find a few minutes to
port it to g7 in the morning.

for drawing fiducial marks it would be better to have the size= option
optionally take a second parameter, but I don't like overloading the
parameter definition like that very much, and adding two new size_ew= and
size_ns= options like g.region does for res= clutters the option list and
Required-> parser setting, so isn't great either.

happy to entertain better ideas..

Hamish

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Ticket URL: <https://trac.osgeo.org/grass/ticket/1372#comment:4&gt;
GRASS GIS <http://grass.osgeo.org>

#1372: Different lat-lon grid size for geographic grids
-------------------------+--------------------------------------------------
Reporter: alf | Owner: grass-dev@…
     Type: enhancement | Status: new
Priority: normal | Milestone: 6.5.0
Component: Display | Version: svn-develbranch6
Keywords: d.grid | Platform: All
      Cpu: Unspecified |
-------------------------+--------------------------------------------------

Comment(by hamish):

merged into trunk in r57714.

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Ticket URL: <http://trac.osgeo.org/grass/ticket/1372#comment:5&gt;
GRASS GIS <http://grass.osgeo.org>