[OSRS-PROJ] SOM-A

Gerald Evenden gerald.evenden at verizon.net
Fri Jan 23 17:18:36 PST 2004


Oh boy!  The only amount that I have looked at it was many years ago and
that was only to check that it could replicate JPS' test numbers.  I  
will give it
a quick look and see if I understand any of it.

At the moment I am about half way through omerc and trying to figure out
a computation in gctp/prpj that is not documented anywhere.  BTW, EPSG  
is
*not* a very good code source.  What is in there is basically JSP'  
workup
but lacks some critical details.  It is not from Hotine.

On Jan 23, 2004, at 4:45 PM, Frank Warmerdam wrote:

> Gerald Evenden wrote:
>> Space obl.. merc is in PROJ.4, basically a copy of gctp.
>> +proj=lsat
>
> Gerald,
>
> It's embarrassing what I don't know sometimes.  I see it is driven by
> the lsat (presumably land sat number) and path values much like the old
> GCTP formulations I have seen.  Would it be hard to update the code to
> support the explicit parameters JPL is suggesting?
>
>  3 Inclination of orbit ascending node.  (angular units)
>  4 Longitude of ascending orbit at equator.  (angular units)
>  7 Period of satellite revolution.  (time in minutes)
>  8 Satellite ratio.  This controls the start and end points of the   
> map on
>     the earth surface.
>
> My presumption is that these are being computed internally from the  
> landsat
> number and path ... is that right?  Are these JPL guys going at the  
> problem
> in a good way to reduce the projection to it's underlying parameters  
> or is
> it just going to make it a huge hassle for people to enter?
>
> Best regards,
>
> --------------------------------------- 
> +--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,  
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent
>
>
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_____________________________________
Jerry and the low riders: Daisy Mae and Joshua

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