DESCRIPTION

The viewproj programs give GRASS users the ability to view lat-lon data in a variety of map projections.

EXAMPLES

The user must open a graphics monitor (using d.mon) before running the examples.

The following examples use d.auto.viewproj, which automatically adjusts the region and sets the projection parameters for the requested view projection.

A Mercator map
n=85.0  s=-85.0  e=449.5  w=90.5
proj=merc  ellps=wgs84  lon_0=-90.0
g.region n=90 s=-90 e=450 w=90
d.erase color=white
d.auto.viewproj projname=Mercator
d.mon.viewproj
d.vect.viewproj map=coastlines color=black
d.grid.viewproj size=10

An Albers Equal Area map
n=85.0  s=-85.0  e=-45.0  w=-135.0
proj=aea  lon_0=-90.0  lat_0=0.0  lat_1=28.33  lat_2=42.5

g.region n=90 s=-90 e=450 w=90
d.erase color=white
d.auto.viewproj projname=AlbersEqualArea
d.mon.viewproj
d.vect.viewproj map=coastlines color=black
d.grid.viewproj size=10
 

An Orthographic polar map
n=90.0  s=0.0  e=450.0  w=90.0
proj=ortho  ellps=wgs84  lon_0=-90.0  lat_0=90.0
g.region n=90 s=0 e=450 w=90
d.erase color=white
d.auto.viewproj projname=Orthographic
d.mon.viewproj
d.vect.viewproj map=coastlines color=black
d.grid.viewproj size=10
 
To retain more control over the view projection, d.set.viewproj may be used instead of d.auto.viewproj.  The user must set the parameters required by the projection.  The user must also set the region appropriately for the projection.

A Lambert Azimuthal Equal Area map
Oblique Aspect

g.region n=89.95 s=-89.95 e=450 w=90
d.erase color=white
d.set.viewproj proj=laea ellps=WGS84 lon_0=-90.0 lat_0=45.0
d.mon.viewproj
d.vect.viewproj map=coastlines color=black
d.grid.viewproj size=10

Note, some versions of PROJ require ellps=wgs84 instead of ellps=WGS84
 

SEE ALSO

d.auto.viewproj
d.set.viewproj
d.mon.viewproj
d.rast.viewproj
d.vect.viewproj
d.grid.viewproj

AUTHOR

Beverly Wallace, Lockheed Martin Space Systems, Sunnyvale, CA, USA