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Unmanned Spaceflight.com _ Chit Chat _ converting planetographic coordinates to planetocentric coordinates?

Posted by: ncc1701d Oct 17 2016, 10:02 PM

Hello
Can someone explain to me the math behind converting planetographic coordinates to planetocentric coordinates and vise versa?
The best info i found is on this link
ftp://naif.jpl.nasa.gov/pub/naif/too...ib/plnsns.html
but it is incomplete and I dont know fortran.
Thank you.

Posted by: nogal Oct 17 2016, 11:08 PM

Hi ncc1701d!

Here is a link to an https://isis.astrogeology.usgs.gov/IsisWorkshop/index.php/Learning_About_Map_Projections#Interactive_Planetocentric_and_Planetographic_DemonstrationIt is part of the https://isis.astrogeology.usgs.gov/IsisWorkshop/index.php/IsisWorkshop which contains a wealth of information in a well explained maner.

You may also like this article: http://www.daviddarling.info/encyclopedia/P/planetocentric_coordinates.html

In ISIS I found this bit of code for planetographic to planetocentric convertion: https://isis.astrogeology.usgs.gov/IsisSupport/index.php?topic=1550.0

Fernando

Posted by: JohnVV Oct 18 2016, 02:12 AM

for the earth in my home state Michigan
the island i like to backpack " Isl Royale" , Lake Desor is at
Planetocentric on the left
Planetographic on the right
is 302 x 125 for Planetocentric
is 302 x 113 for Planetographic
at 60 PPD
http://imgbox.com/KAvG6YMT

depending on the resolution and latitude this might be as little as 1 or 2 px or 50+

Planetocentric is a circle ( center is used)
Planetographic is an Ellipse ( the focus points of the ellipse are used )

Posted by: ncc1701d Oct 18 2016, 07:40 AM

thanks guys for the info!