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Atmospheric scattering, with terrain shader preview

An exciting "new" option in FlightGear, that includes reflections, lightmaps, the particle system etc.. A lot is yet to be discovered/implemented!

Re: Atmospheric scattering, with terrain shader preview

Postby Gijs » Sat May 21, 2011 12:05 pm

Actually it was removed from Git yesterday (and thus will be gone with the upcoming Developer Snapshot, as those are based on Git), due to some major issues wit it. Once those are solved it can be added back in.
See http://code.google.com/p/flightgear-bug ... ?id=319#c3
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Re: Atmospheric scattering, with terrain shader preview

Postby kyokoyama » Sat May 21, 2011 6:39 pm

Oh. Alright; thanks for the correction.
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Re: Atmospheric scattering, with terrain shader preview

Postby redneck » Sun May 22, 2011 5:16 pm

Now, I specifically asked about the issues it had, and when they would be solved. Sigh. I guess it's a good thing I had so many problems getting the video to work. Would have been a disaster to show off such an inaccurate feature.
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Re: Atmospheric scattering, with terrain shader preview

Postby Tunisair » Sun Jun 05, 2011 1:34 pm

Where´s the download link please :D
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Re: Atmospheric scattering, with terrain shader preview

Postby Zan » Wed Jun 08, 2011 7:26 pm

There's a link somewhere on this thread, but I'm not sure if it's worth trying as it's very much work in progress only...

I've been messing with the terrain shader too, but I cannot get results that I like... They always look unrealistic in some way. I'd like to have proper extinction when visibility is low (no white haze, but grey or something) for example. And currently the skydome shader shows a black band which I assume is caused by mie scattering... bleh, too much tuning :p

Some images, these are different parts of the shader, so they just show some aspects of how the shader works...
First, light extinction caused by mie scattering when turbidity is 2 or 12 (clear weather vs. very misty)
Image
Image

And in scattering caused by rayleigh scattering:
Image

Edit: One more, shows some effects when the values are way off (two hours after sunset):
Image

I keep doing this, slowly, but I might get it done well enough some day.. :)

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Re: Atmospheric scattering, with terrain shader preview

Postby Liam » Wed Jun 08, 2011 11:25 pm

Zan wrote in Wed Jun 08, 2011 7:26 pm:And in scattering caused by rayleigh scattering:
Image


Now THAT is an improvement!, The only thing I disliked about the atmoscat (as i call it) about it is how perfect it is in comparison to the terrain- which now as you have shown, with a shader to match, makes it perfect. Shame it is no longer in GIT, I will refrain from updating until it's back in as I enjoy it greatly.
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Re: Atmospheric scattering, with terrain shader preview

Postby Thorsten » Thu Jun 09, 2011 6:50 am

I'd like to have proper extinction when visibility is low (no white haze, but grey or something) for example.


Then you need to model a different set of equations for optically thick media. O'Neil's set of equation makes the assumption up front that you're optically thin, so it can't get low visibility realistic no matter what the parameters are.

If you're looking into haze, you're seeing light diffusion - photons after a large number of scatterings, so that they don't retain much directional information. And the light you see is grey rather than white because the amount of photons is diminished due to backscattering into space.

The horizon color is actually a rather interesting problem illustrating that - for a clear atmosphere, it is dark because you see largely space with some Rayleigh blue in (that your shader gets nicely). For more scattering centers, it gets white as the horizon line just gets to the limit of optical thickness, i.e. all photons reach the possible scattering point, a large fraction of them is scattered once, some of them towards you (the shader also captures that). But for yet more scattering centers, the atmosphere is optically thick and the horizon line is not coloured by a single in-scattering but by light diffusion, and that means that the horizon greys and darkens again due to the reflection effect. And for that, you need so solve a different problem.
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Re: Atmospheric scattering, with terrain shader preview

Postby planetacancun » Sat Jun 18, 2011 8:45 pm

Hehe I haven't upgraded my GIT cause I want to make some video with it! Why couldn't be like enable it as an experimental shader? Taking in account that is not accurate. So we could all see the progress Zan makes... +1 coin.
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Re: Atmospheric scattering, with terrain shader preview

Postby fredb » Sat Jun 18, 2011 8:50 pm

Some code had side effects even when this/all shader was/were disabled (black fog)
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Re: Atmospheric scattering, with terrain shader preview

Postby planetacancun » Sun Jun 19, 2011 7:53 pm

fredb wrote in Sat Jun 18, 2011 8:50 pm:Some code had side effects even when this/all shader was/were disabled (black fog)


I see. Thanks for the reply. I guess I'll keep it until I'm done using it on videos...
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Re: Atmospheric scattering, with terrain shader preview

Postby zhbl » Fri Jul 01, 2011 7:54 am

I downloaded file, but don't know how to make them effective, please give directions, thank!!!!!
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Re: Atmospheric scattering, with terrain shader preview

Postby Sealbhach » Fri Jul 01, 2011 8:03 am

The controls are in the View/Rendering Options menu.

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Re: Atmospheric scattering, with terrain shader preview

Postby eekpo » Thu Aug 18, 2011 3:25 pm

canceled
Last edited by eekpo on Fri Mar 30, 2012 8:46 pm, edited 1 time in total.
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Re: Atmospheric scattering, with terrain shader preview

Postby truthsolo » Thu Aug 18, 2011 3:54 pm

eekpo, I asked about this in a new topic about LoD Ranges, but so far I have only heard that "LoD Range does not do anything" and "turn off METAR"—which is not an option for me, real weather is essential. Another problem with the tiles not loading is that you can see the sun and light from it when you should not be able to (I think this is because of missing tiles anyway). I am eager to find a solution as well.

I also wanted to point out that there is a huge tear in the sky when using the new skydome shader, which is visible behind the wing root in your screenshot. It makes you feel as though you really are in a dome, as opposed to an atmosphere.

Third comment (or request, if you will): are there any plans to change the colors based on lattitude, time-of-day, and weather conditions? What works for one part of the world doesn't necessarily happen everywhere else. For instance, I see red and purple skies almost every afternoon in Florida—I've never seen a cow-patty-colored sky in my life though, no matter where I lived.

It is quite impressive so far though, so keep up the great work, Zan!
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Re: Atmospheric scattering, with terrain shader preview

Postby eekpo » Sun Aug 21, 2011 1:55 pm

canceled
Last edited by eekpo on Fri Mar 30, 2012 8:44 pm, edited 1 time in total.
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