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Sunrises (version 1.3 available)

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

Re: Sunrises (version 1.2 available)

Postby Thorsten » Mon Apr 16, 2012 5:48 am

And... snow makes its appearance in lightfield rendering... (still needs some gradient effect to get the steep mountain slopes right, but that should be easy).

Image
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Re: Sunrises (version 1.2 available)

Postby Thorsten » Mon Apr 16, 2012 3:39 pm

Transition to a nicer snow texture and a gradient effect:

Image

And... here comes the dust effect for dry regions. Nellis AFB after some refreshing rain:

Image

Nellis AFB after a few weeks of dry weather:

Image

Time to test-fly everything!
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Re: Sunrises (version 1.2 available)

Postby ot-666 » Mon Apr 16, 2012 4:53 pm

Brilliant and absolutely stunning work :shock: :D
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Re: Sunrises (version 1.2 available)

Postby penta » Mon Apr 16, 2012 6:21 pm

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Re: Sunrises (version 1.2 available)

Postby kyokoyama » Mon Apr 16, 2012 9:26 pm

Amazing as always -great job!

Just curious... does this new feature addition also involve texture changes, or is it really only the light and atmosphere that changes?
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Re: Sunrises (version 1.2 available)

Postby Sealbhach » Tue Apr 17, 2012 1:21 am

I love the dust effect. It would be cool to fly from there when it's all dusty and then fly back the next day when it's raining.

.
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Re: Sunrises (version 1.2 available)

Postby Thorsten » Tue Apr 17, 2012 6:39 am

Just curious... does this new feature addition also involve texture changes, or is it really only the light and atmosphere that changes?


Neither actually. Inside the shader, you have (among other things) texture color of a pixel and light color as input, and you have to specify an output pixel color. How (or even if) you relate these things is up to you. Usually light and texture color determine the base pixel color based on a Phong lighting model which is then corrected for fog in the last step.

For the lightfield for instance, I discard the input light color and replace it by a position-dependent color vector which is computed inside the shader. You could do very weird things with a shader, say an altitude dependent emissive glow, or a fog that whitens out close objects and leaves distant objects unaffected...

For the dust effect, I modify the base texture color before passing it to the lighting equation. For the snow effect, the base texture color gets replaced by an alternative snow texture based on altitude. I've actually been thinking that it'd be nice to have an autumn-colors effect based on a hue rotation of a forest texture. What's keeping me at the moment is that it's complicated not to do this for needle forest at the same time, and that my non-GPL forest textures may respond to the rotation in a different way than the default textures.
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Re: Sunrises (version 1.2 available)

Postby Thorsten » Wed Apr 18, 2012 3:14 pm

Thanks to the helpful silence on the devel list in response to my question how noise in the shaders works, I had to work out the format of the noise textures by trial and error, but I think I understand now how this goes... Noise textures allow for very neat effects it seems...

Smooth fogging as we had it so far:

Image

And... Abracadabra, some structure in the fog appears. This looks like cloud models, but it has in fact none of the negative side effects of low cloud models intersecting with the terrain - it is a true 3d fogging structure (it's not actually a 3d density distribution rendered, because that is too small, the effect just changes the fog density along a view ray, but still, dense patches remain at the correct location and so on).

Image
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Re: Sunrises (version 1.2 available)

Postby Sealbhach » Thu Apr 19, 2012 2:24 am

How is it at ground level? Does it mean if you were flyng an approach through this fog you would get variable visibility? Because that would be cool. Flying through a dense fog patch, then it clears up very slightly, then dense fog again.

.
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Re: Sunrises (version 1.2 available)

Postby Thorsten » Thu Apr 19, 2012 6:13 am

How is it at ground level? Does it mean if you were flyng an approach through this fog you would get variable visibility? Because that would be cool. Flying through a dense fog patch, then it clears up very slightly, then dense fog again.


Yes and no... It's not rendering a *real* 3d for distribution. Think of a visibility multiplier attached to a vertex - when you look at a certain spot, it will always be more fogged than a different spot nearby, but as you close in, the overall fog level decreases. So unless you're looking very closely, it creates a plausible impression, but (as with the rotating cloudlets in 3d clouds) if you know how it's done and what you should be looking for, you can see what is really happening.

Also, in more dense fog, the differences just whiten out because it doesn't matter if the visibility is 500 m or 550 m, both give you white when the vertex you're looking at is 3000 m distant.

Most of the time it is rather subtle, and in the screenshot I maximized the effect.
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Re: Sunrises (version 1.2 available)

Postby Thorsten » Thu Apr 19, 2012 7:15 pm

I added an experimental Mie shader to thin clouds - what this means is that thin clouds light up when the sun is approximately behind them, but thick clouds continue to block the sunlight and their back is in shade. The combined effect of Mie and diffuse scattering is nothing short of awesome. It creates a dramatic mixture of light and shadow at predawn:

Image

At dawn, a golden halo lights up around the sun and creates colors that just... jump out of the screen.

Image

During the day, the effect is more subtle, but note how the whole cloud lights up when the sun is hidden behind it, and how the cloud in front shades the Mie light.

Image
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Re: Sunrises (version 1.2 available)

Postby curt » Fri Apr 20, 2012 3:19 pm

Looks amazing Thorsten. Will this work by default with the non-rembrandt rendering path in the current git version?
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Re: Sunrises (version 1.2 available)

Postby fredb » Fri Apr 20, 2012 3:31 pm

Hi Curt, all of this is non-Rembrandt stuff.
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Re: Sunrises (version 1.2 available)

Postby Rickbritto » Fri Apr 20, 2012 4:25 pm

amazing work Thorsten, two very promising projects is their , and rembrandt

congratulations to all of you
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Re: Sunrises (version 1.2 available)

Postby Sealbhach » Fri Apr 20, 2012 8:47 pm

The third picture looks awfully realistic. :shock:

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