Basemap offers many projections, but is missing two of the most useful ones:
- For satellite applications, it would be helpful to have a "camera"
projection, i.e., a projection that shows the Earth as viewed from a
specified point in space. This would be a generalization of the current
geostationary projection.
- Basemap current offers North-Polar and South-Polar azimuthal equidistant
projections. A useful generalization is the azimuthal equidistant
projection with a specified latitude and longitude at the center of the map.
···
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If and when you have time on your hands, a projection that is rarely used but
quite interesting is Guyou's Doubly-Periodic Projection. (See the first and
third figures in http://www.members.shaw.ca/quadibloc/maps/mcf0703.htm).
This projection puts the worst distortion at four points in the ocean, and
does a reasonable job of preserving the shapes and relative sizes of the
major land masses.
···
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Dr. Phillip M. Feldman wrote:
Basemap offers many projections, but is missing two of the most useful ones:
- For satellite applications, it would be helpful to have a "camera"
projection, i.e., a projection that shows the Earth as viewed from a
specified point in space. This would be a generalization of the current
geostationary projection.
Philip: Don't think the proj4 lib supports this.
- Basemap current offers North-Polar and South-Polar azimuthal equidistant
projections. A useful generalization is the azimuthal equidistant
projection with a specified latitude and longitude at the center of the map.
That's already implemented - just use the 'aeqd' projection, specifying lat_0,lon_0,width and height keywords.
-Jeff
Jeff Whitaker wrote:
Dr. Phillip M. Feldman wrote:
Basemap offers many projections, but is missing two of the most useful ones:
- For satellite applications, it would be helpful to have a "camera"
projection, i.e., a projection that shows the Earth as viewed from a
specified point in space. This would be a generalization of the current
geostationary projection.
Philip: Don't think the proj4 lib supports this.
I think it's already in there -- see nsper, for near sided perspective.
-Andrew
Andrew Straw wrote:
Jeff Whitaker wrote:
Dr. Phillip M. Feldman wrote:
Basemap offers many projections, but is missing two of the most useful ones:
- For satellite applications, it would be helpful to have a "camera"
projection, i.e., a projection that shows the Earth as viewed from a
specified point in space. This would be a generalization of the current
geostationary projection.
Philip: Don't think the proj4 lib supports this.
I think it's already in there -- see nsper, for near sided perspective.
-Andrew
Hello Andrew-
It does sound as thought nsper is exactly what I need, but when I try to use it, I get the following error message:
ValueError: 'nsper' is an unsupported projection.
The supported projections are:
aeqd Azimuthal Equidistant
poly Polyconic
gnom Gnomonic
moll Mollweide
tmerc Transverse Mercator
nplaea North-Polar Lambert Azimuthal
gall Gall Stereographic Cylindrical
mill Miller Cylindrical
merc Mercator
stere Stereographic
npstere North-Polar Stereographic
geos Geostationary
vandg van der Grinten
laea Lambert Azimuthal Equal Area
mbtfpq McBryde-Thomas Flat-Polar Quartic
sinu Sinusoidal
spstere South-Polar Stereographic
lcc Lambert Conformal
npaeqd North-Polar Azimuthal Equidistant
eqdc Equidistant Conic
cyl Cylindrical Equidistant
omerc Oblique Mercator
aea Albers Equal Area
spaeqd South-Polar Azimuthal Equidistant
ortho Orthographic
cass Cassini-Soldner
splaea South-Polar Lambert Azimuthal
robin Robinson
Phillip
Phillip M. Feldman wrote:
Andrew Straw wrote:
Jeff Whitaker wrote:
Dr. Phillip M. Feldman wrote:
Basemap offers many projections, but is missing two of the most useful ones:
- For satellite applications, it would be helpful to have a "camera"
projection, i.e., a projection that shows the Earth as viewed from a
specified point in space. This would be a generalization of the current
geostationary projection.
Philip: Don't think the proj4 lib supports this.
I think it's already in there -- see nsper, for near sided perspective.
-Andrew
Hello Andrew-
It does sound as thought nsper is exactly what I need, but when I try to use it, I get the following error message:
ValueError: 'nsper' is an unsupported projection.
The supported projections are:
aeqd Azimuthal Equidistant
poly Polyconic
gnom Gnomonic
moll Mollweide
tmerc Transverse Mercator
nplaea North-Polar Lambert Azimuthal
gall Gall Stereographic Cylindrical
mill Miller Cylindrical
merc Mercator
stere Stereographic
npstere North-Polar Stereographic
geos Geostationary
vandg van der Grinten
laea Lambert Azimuthal Equal Area
mbtfpq McBryde-Thomas Flat-Polar Quartic
sinu Sinusoidal
spstere South-Polar Stereographic
lcc Lambert Conformal
npaeqd North-Polar Azimuthal Equidistant
eqdc Equidistant Conic
cyl Cylindrical Equidistant
omerc Oblique Mercator
aea Albers Equal Area
spaeqd South-Polar Azimuthal Equidistant
ortho Orthographic
cass Cassini-Soldner
splaea South-Polar Lambert Azimuthal
robin Robinson
Phillip
Philip: I think Andrew meant nsper is in proj4. I'll look into adding support for it in Basemap.
-Jeff