[GRASS-dev] Missing projections

[Morten Hulden]

Glynn Clements wrote:
> Maciej Sieczka wrote:
> 
>>> The following projections are listed by "proj -lp" but don't have
>>> entries in proj-parms.table:
>>>
>>> 	geos : Geostationary Satellite View
>>> 	lcca : Lambert Conformal Conic Alternative
>>> 	sterea : Oblique Stereographic Alternative
>>> 	vitk1 : Vitkovsky I
>>>
>>> Can anyone provide the necessary parameter information, i.e. which
>>> PROJ parameters they accept, and what (if any) default value should be
>>> used?

geos projection needs only longitude and height (but doesn't say no to 
kfact). Latitude seems to be fixed at 0 degrees. In reality most 
geostationary satellites seem to deviate a little from 0 degrees. Pity, 
because then geos can't be used (but nsper projection can). Height is 
usually about 35700-35800 km.

http://www.n2yo.com

GEOS:HEIGH=ask,35800000.0;LON0=ask,20.0


> I'm not sure where the LON0 default comes from; of 121 projections,
> 119 accept LON0 (UPS and UTM are the exceptions), and 100 of those
> have 20 as the default.

I can explain that. I had a test map centered around lon 20, lat 55 when 
I added the projections back in 1998. I used 20/55 as default for most. 
May not please everyone to have Europe as default but was better than 
making up something for which I did not have a map and could not test. 
And using "neutral" 0/0 was not valid for many projections so I chose to 
use a real world example as default.


Morten