Celestia Forums

It probably is, but I'm asking just to be sure.

I'm talking about what happens when the Mie/Rayleigh atmospheric scattering codes are applied to giant planets and then viewed from large distances and high zooms.



Is this a bug, or a limitation of Celestia?

I was previously unaware of it, but it does happen on my computer too.
Strangely, it doesn't happen when looking at the Earth from a large distance.

I have to consider it a bug.

Actually, I've seen it on Earth too, when viewed at the same distance but with higher zooms (enough to make Earth cover the same portion of the screen as Jupiter did in the screenshot). I think the bug is less noticeable due to Earth's smaller physical size, because I gave Earth the Jupiter texture, and the bug was still less noticeable than if Earth were as large as Jupiter.

Hi, now I cannot experimenting about because I'm not at my computer, thus a quick thought in seeing that. Could be tested on gas giants by removing the rings directives?

One of the variables is the distance between the planet and the star. It seems closer planets suffer this effect a bit less than planets further from their star.

I determined this by being 1 AU away and zoomed in on a planet that is close to the star, compared to being 1 AU away and zoomed in on a planet that is much further from the same star.

Fenerit wrote:Hi, now I cannot experimenting about because I'm not at my computer, thus a quick thought in seeing that. Could be tested on gas giants by removing the rings directives?

It doesn't matter whether or not the object has rings around it. In the screenshot above, Jupiter does not have rings. I did observe the same bug on a planet that did have rings, and removing the rings did not fix it.

PlutonianEmpire: what is the MieScaleHeight for gas giants settings? It cannot be the same of Earth, of course.

Fenerit wrote:PlutonianEmpire: what is the MieScaleHeight for gas giants settings? It cannot be the same of Earth, of course.

For Jupiter, the MieScaleHeight was 15. For the other gas giant, it was 35.

I still see the same bug on Earth too. Here's the view from Jupiter:



I can see the bug, but it is significantly less noticeable.

Still can't see it? Look at the terminator. The artifacts are very subtle, but they're there.

EDIT: Also, look at them in real-time, with Celestia *not* paused. You'll see it is quite dynamic.

You mean the "cut off" of terminator's curvature? Yes, I see that. For gas giants do try 130.

Fenerit wrote:You mean the "cut off" of terminator's curvature? Yes, I see that. For gas giants do try 130.

Bug is still there.

Personally, I avoid MieScaleHeights anywhere above 40 or 50, because anything above that starts to darken the object, both on the surface and when seen from space.

Yes, because also Mie need to be set. But if the bug still there, it must be the same and not changing as Mie parameter changes. I suppose the bug "looks" in the same manner. Maybe some zoom-experiments on Titan could tell more...

Fenerit wrote:Yes, because also Mie need to be set. But if the bug still there, it must be the same and not changing as Mie parameter changes. I suppose the bug "looks" in the same manner. Maybe some zoom-experiments on Titan could tell more...

They do.

Just checked it out.

Apparently, with Titan's default settings, there is no artifacting, even at maximum zoom and large distances, except for when it covers a tiny fraction of the screen. Giving it an Earthlike atmosphere makes the artifacting return.

Bah... Here the "bosses" are Fridger and Chris... I can just wonder about. Being Mie/Rayleigh's parameters the scattering and the absorption of shaders, they behaves diversely when the object is directly illuminated or half-illuminated or back-illuminated. Maybe it is absorped even the shader's feature that gives the basic object's to lighting/shadowing. I'm fairly sure that for gas giants is matter of good settings, tough. For the Earth, the last supposition to check it out is seeing what happens without the NightTexture directive.

EDIT LATER:
Notice how MieScaleHeight for Titan be 18.3 times that of Earth whereas MieAsymmetry is just a bit more of the double.

Hi! My experiments with such an issue.

I can confirm such artifacts on Earth and Titan but Jupiter. Jupiter's Mie parameters are the same of Titan with the exception of MieScaleHeight = 130 and MieAsymetry = -0.05. Suppose that "zoom-in" be the shift + left drag, I get this:

EARTH (from 5.53 au):

No extra textures loaded (but is the same with them) and no add-ons hidden inside (but is the same with them). Such artifacts are shown when I do act on mouse-wheel after "arrival"; during the zoom-in's approach no artifacts are shown.

TITAN (from 10.41 au):

Is the same of the Earth: approach doesn't shows artifacts, after mouse-wheel moving, yes.

JUPITER (from 16.68 au):

No artifacts at all, neither in approach nor when the mouse-wheel is moved.