Track while keeeping the horizon downards

Description: All about writing scripts for Celestia in Lua and the .cel system

Jairo Amaral
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Jairo Amaral
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Age: 37
Posts: 3
With us: 6 years 5 months
Location: S?o Jos? dos Campos, S?o Paulo, Brazil

#1by Jairo Amaral » 16.08.2017, 13:39

I'm used to Celestia, but I'm a newbie for scripting.

I'd like to use Celestia to teach position astronomy. I want to make lots of comparisons between what is seen from the ground, and what is seen from space, specially in time lapse.

My greatest problem with scripting is that I couldn't find a way to track an object in the sky like an azimuthal mount would do, -- keeping the horizon at the bottom of the image -- you know, like a human being would do from Earth. Celestia seems to keep an absolute orientation, so Earth's horizon keeps dancing around the image while the image doesn't rotate at all -- and that defeats the purpose of showing what someone would actually see.

Is there a simple way to do it that I'm missing? Has anybody done this before?

If this doesn't exist, could it be done with the available languages? Math is not a problem for me.

Regards,

selden
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selden
Posts: 10089
With us: 15 years
Location: NY, USA

#2by selden » 16.08.2017, 19:40

Celestia does have an alt-az mode: keyboard Ctrl+f, celx setaltazimuthmode

See https://en.wikibooks.org/wiki/Celestia/Celx_Scrip ... elx_celestia#setaltazimuthmode

I dunno if that does everything you want, though.

A workaround might be to define a SurfaceObject (which automatically stays perpendicular to the local surface) and do the movements relative to that instead of relative to the planet's surface. See https://en.wikibooks.org/wiki/Celestia/SSC_File#S ... th.22_.7B_...parameters..._.7D
Selden


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