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[Uriah]

Hi everyone!

Is it possible to find the right balance of the Environment Atmosphere settings to look realistically like Mars? What about Venus or Pluto, or some of the moons in the solar system?

I found that if you tweak with the atmosphere settings enough, it is possible to produce results which look very much like the Martian atmosphere, and this will be very helpful in the future when Outerra expands to the other planets in the solar system. I have posted my initial results below along with the Atmosphere settings and some real images of Mars for comparison. I would like to see if anyone else can come up with better settings which works for all altitudes and times of day. The biggest issue I have found is not making everything too hazy or orange-red, while getting a nice blue-green tone sunrise and sunset.

Here are some facts about the Martian atmosphere and how the Outerra Atmosphere settings can be used to simulate it.

• First of all, the Atmosphere is just 1% the density of Earth's, so the Scattering parameter should probably be much lower.
• The sun is much further away than it is on Earth, so the Sun Intensity parameter should probably be somewhat lower.
• The sky during daytime is an orange-yellow, which I used the rayleigh absorption parameters to simulate this effect.
• The sky during sunrise and sunset is actually a blue-green tone, which can be simulated with the correct balance of scattering and absorption parameters. I found the most difficulty with simulating the correct sky color and sunrise/sunset color due to the fact that when you increase the scattering parameter to make the sunrise/sunset more of a blue-green tone that just isn't realistic because there is too much haze. Making the rayleigh parameters more of a red tone also makes the sunrise/sunset more blue-green, however makes the sky during daytime too red. I need to find a better balance of these parameters which isn't too hazy or red but makes a blue-green sunrise/sunset.
• The visible light from the Sun is not white, since it is a yellow dwarf. I set the Sun color to a mild orange tone instead of yellow because it changes the terrain color. With accurate terrain diffuse albedo color, the Sun color should probably be a more yellow tone.
• There are in fact clouds and weather on Mars, which I omitted in these screenshots.

It would be awesome if people would play around with these settings and post their results, most importantly a screenshot with what settings you use!

Best regards,
Uriah

My current Mars atmosphere settings:



Comparisons at different times of day and altitudes using the exact same Atmosphere settings. (Click image to enlarge)









A few real pictures from Mars.

[Uriah]

This post is reserved for screenshots of the final Atmosphere settings for each planet.

[Acetone]

What a nice idea!

Venus test:

The only colors we have are artificial recreations with the Venera probes pictures, but it's possible to get some nice results:




Settings:


Orbital screenshot, color variations from global cloud coverage not present, but it looks good, maybe too yellow-ish, but it's hard to tell if the colors in the pictures are accurate:

[Uriah]

Nice! I'm changing the topic subject to all planets instead of specifically Mars! :DD

[Acetone]

Cool

And some Moon tests:
The hard part here is the ground textures. I had to change the sun light to something close to grey and go to very light color areas of earth (deserts) to find something good. No atmosphere, and the ground is very reflective (you know what I mean if you ever have watched the moon with a telescope and no filter, one or two minutes and you eyes start to hurt.



Settings:


In fact, because of the bloom, 100 sun intensity is maybe even better:

[Uriah]

Interesting!

Yeah the moon is the next logical candidate for being generated using the Outerra procedural algorithms. Since the Lunar Reconnaissance Orbiter Camera (LROC) has gathered great elevation and diffuse albedo data over the years, it would be mostly a matter of processing the data and tweaking the procedural parameters according the Cameni.

The WAC Empirically Normalized Reflectance map is sufficient with the addition of the polar maps. Here is the entire set of LROC Global Products which are available, notably the GLD100 WAC Global DTM which provides 100 meters per pixel resolution.

The available Mars global DTM and diffuse albedo normalized reflectance products have a lot more issues and post processing involved before they would be useable.

Hopefully Outerra will have additional planets sometime in the future, but until then, we have the atmospheric settings! 

[cameni]

The visible light from the Sun is not white, since it is a yellow dwarf. I set the Sun color to a mild orange tone instead of yellow because it changes the terrain color. With accurate terrain diffuse albedo color, the Sun color should probably be a more yellow tone.[/li][/list]

Just a note, "white" as such doesn't exist
Correctly there would have to be spectral intensities for major wavelengths. In OT the white star color corresponds to the spectrum of our Sun (without atmospheric absorption).

[Uriah]

Ah, good point, in fact viewed from space without atmospheric absorption the sun is essentially white.

[Uriah]

Comparison of three different atmospheric settings.

Top row is original from first post, second row and third row both have original OT sun color and variations on the rayleigh parameters. I think the second and third row, especially the third, look far more realistic already in comparison to the real images of Mars.







Outerra vs. Mars comparison. Outerra on the left, Mars on the right.