Do you need ellipsoidal earth for orthographic, or is spherical sufficient?
Philip Bentley wrote:
> Hi Don,
>
> Vertical Perspective projection made it into CF 1.2, which is why I
> didn't mention it. Yes, I was also assuming that GoogleEarth uses a
> tilted perspective-type projection. But for general whole-globe views,
> the orthographic projection is a useful alternative (and obviously the
> limiting case of vertical perspective - i.e. the perspective point is at
> inifinity).
>
> Regards,
> Phil
>
> On Wed, 2008-05-21 at 07:05 -0400, Don Murray wrote:
>> Phil/Ethan-
>>
>> Philip Bentley wrote:
>>
>> > An obvious one perhaps, but one which we may find increasingly useful /
>> > relevant in light of the rise and rise of GoogleEarth-type applications,
>> > is the Orthographic projection. This being the classic 'view from space'
>> > projection.
>> >
>> > Same grid mapping parameters as the other azimuthal projections, viz.
>> >
>> > grid_mapping_name = "orthographic"
>> >
>> > longitude_of_projection_origin
>> > latitude_of_projection_origin
>> > false_easting
>> > false_northing
>> >
>> > (though off the top of my head I can't think of a scenario where one
>> > would want to use the last two params).
>>
>> I think GE actually uses a tilted perspective view. But,
>> I think CF should support the Vertical Perspective with
>> an ellipsoid. EUMETSAT has GRIB messages with this projection
>> and an elliptical earth.
>>
>> Don
>
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Received on Tue May 27 2008 - 11:38:24 BST
