[OSRS-PROJ] Inverse function of a quadrant is wrong?
Alexander Weidauer
alex.weidauer at huckfinn.de
Thu Apr 10 14:03:47 PDT 2003
Hi Gerald,
Sorry to arge you about this theme, but I hoped that I got propper
exceptions or overflow remarks will ocour, if the coodinates leaves the
space of correct or possible solution. For the stere it is quite simple
to determin the range of propper coordinate solutions. But if somebody
use the API whith no idea of projections, the programmer (in this case
I) has to prevent the errors by the API.
The inverse is not so mutch relevant for the animation but more for
other demos or applications, witch have a cursor over the map image
that shows both (plain coordinates and longitude latitude coordinates)
in a status panel and this will fail.
Never than less, thank you for your help.
Regards Alex Weidauer.
Gerald I. Evenden schrieb:
> You lost me. I can understand an animation of shifting origin but
> I do not understand the need for the inverse. Secondly, if the
> animation is more-or-less global in extent the spherical form
> would seem more appropriate.
>
> None of this excuses the apparent failure of PROJ.4 to do a
> proper inverse.
>
> This all brings me back to my recent nemesis: the Gaussian Sphere:
> I still have not resolved the differences between Snyder, Thomas,
> Pearson, Swiss Projection, Krovak and alternate stereographic.
> Some of these folk have elided the constants of integration
> and I can't figure out why and what justification was used.
> Are there any good mathematical cartographers out there who
> have been through this material?
>
> Snyder seems to use the conformal sphere as an intermediate
> step in the stereographic but I can' simply match the procedures
> with what I have done with the other examples. AARRRRGGGHHHH!
>
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