Star Atmosphere

[Ivvi]

Dear All,
the magnificent star atmosphere which was in Celestia 1.4.1 is lost in 1.5.0 (please see the attached images).
1.4.1:

1.5.0:

I have read that Chris removed the atmosphere altogether somewhere on the way to the pre-release2. However, there is a feature of Ctrl+A so that one could remove the star atmosphere if one wanted to... But now that the stars are devoid of the atmosphere completely they are LAMENTABLE. I don't like the thing in 1.5.0 pre1 either, the one which was in 1.4.1 was definitely more realistic, you can feel the "heat and glow" of it

[ajtribick]

I'll just warn you now that claiming this feature was "realistic" is treading on dangerous ground in these parts.

The feature may have been "convincing" (depending on how much knowledge of the phenomena involved you have), but "realistic" is an entirely different kettle of fish.

As for whether anything's going to get done about this (or any other bugs/issues in the prerelease), there are a few threads around the boards which might prove informative.

[Ivvi]

I'll just warn you now that claiming this feature was "realistic" is treading on dangerous ground in these parts.

The feature may have been "convincing" (depending on how much knowledge of the phenomena involved you have), but "realistic" is an entirely different kettle of fish.

You are probably not going to deny that having an atmosphere is more realistic than having no atmosphere, now that the real Sun does have one. That's pure logic, I'm afraid. The images show my point pretty well, I hope.

[ajtribick]

Was the atmosphere as displayed before "realistic" though? That is the question.

The philosophy round these parts (back when there was a development process to have a philosophy about) was that it is better not to implement a feature than to implement it incorrectly.

[Hamiltonian]

Yes. You don't need to spend too long looking at the sun (projected!) to notice that it has no fringe of atmosphere around the edge. The hard edge is more "realistic", tho it could use some limb darkening.

[Hungry4info]

...tho it could use some limb darkening.

I'm about to vomit.

Limb darkening isn't needed, as it's not observable with the naked eye. The stars in Celestia are darkened enough already anyway. I fear if such "improvements" are made, the stars will eventually resemble metal-grey circles without flares or atmospheres.

[Ivvi]

Was the atmosphere as displayed before "realistic" though? That is the question.

Yes. You don't need to spend too long looking at the sun (projected!) to notice that it has no fringe of atmosphere around the edge. The hard edge is more "realistic", tho it could use some limb darkening.

Technically you are right, because you obviously rely upon images like those made by NASA. These are made focused directly on the sun, and the lack of dynamic range prevents us seeing the chromosphere and the corona, actually.
But Celestia is a tool for space simulation, it shows you the space as if you were looking at it with your eyes, not your photocameras or telescopes. If you look at the sun from here or from Moon, in the natural circumstances where one has to consider the full dynamic range of the visible light you will not see anything like these NASA images. You will see a very hot glowing sphere. I don't know why the stars in Celestia lost the impression of "hot and glowing" but they did lose it. This is the only reality I consider. Please do not think I do not understand your position. I know that hard edge representation makes it more photorealistic. I just fear that Celestia is getting more photorealistic than eye-realistic and I also do not understand why Ctrl+A could not be made so as to switch between the modes to serve those who accept your point and those who accept my point.

[ajtribick]

I'm about to vomit.

What an immature reaction. The phenomenon of limb darkening is real and observable, which means that if we can model it in a consistent way, we should.

In fact, what we should do is use something like HDR+luminous bloom and then stick in the limb darkening. That way you could adjust the "exposure" (or dilation of the virtual eye's pupil if you want to think about it like that) to go between a blinding ball of light or to view the sunspots etc.

If you look at the sun from here or from Moon, in the natural circumstances where one has to consider the full dynamic range of the visible light you will not see anything like these NASA images. You will see a very hot glowing sphere. I don't know why the stars in Celestia lost the impression of "hot and glowing" but they did lose it.

Because the "hot and glowing" effect was not based on any physically-justifiable model. There was (at one stage) a long debate about how to do this "luminous bloom" effect properly, which pretty much requires using HDR. During the debate, Chris Laurel lost patience with the whole thing and removed the stellar atmospheres, which is not the ideal way to go about things.

[buggs_moran]

I still always thought it would be neat to have the ability of filters. This way you could have the full glare associated with the sun fill your screen at naked eye, but throw on an Xray filter and bingo, just like SOHO. Naked eye (no filter) viewing could have the star increase in brightness as you approached it. Eventually glaring out the viewscreen, unless of course, a filter is applied.

[Hungry4info]

The phenomenon of limb darkening is real and observable...

No arguement here. But is it observable to the naked eye as Celestia was originally supposed to resemble?

In fact, what we should do is use something like HDR+luminous bloom and then stick in the limb darkening. That way you could adjust the "exposure" (or dilation of the virtual eye's pupil if you want to think about it like that) to go between a blinding ball of light or to view the sunspots etc.

I still always thought it would be neat to have the ability of filters. This way you could have the full glare associated with the sun fill your screen at naked eye, but throw on an Xray filter and bingo, just like SOHO. Naked eye (no filter) viewing could have the star increase in brightness as you approached it. Eventually glaring out the viewscreen, unless of course, a filter is applied.

I think those are wonderful ideas.

What an immature reaction.

It was serious nonetheless. I'm very passionate on the issue, and it sickens me to even think about how much Celestia is deteriorating. I apologize if it comes across to you as "immaturity".

[Ivvi]

Does anyone know what should be changed in the source code if I want to bring back the stellar atmospheres an?? compile Cleestia personally for myself?
Thanks for all who knows and helps here.

[Hungry4info]

Does anyone know what should be changed in the source code if I want to bring back the stellar atmospheres an?? compile Cleestia personally for myself?

Yeah, I asked that once before as well. http://www.celestiaproject.net/forum/viewtopic.php?t=11123

Easy ...fog up your monitor screen.

[Ivvi]

Yeah, I asked that once before as well. http://www.celestiaproject.net/forum/viewtopic.php?t=11123

Easy ...fog up your monitor screen.

LOL yeah that solves everything I'd rather propose smearing the star with mineral oil. Be it a copyrighted idea now LOL

[Hamiltonian]

The phenomenon of limb darkening is real and observable...

No arguement here. But is it observable to the naked eye as Celestia was originally supposed to resemble?

It's visible to the filtered naked eye, certainly. The naked eye can't see sunspots on the unfiltered solar disc. Do we remove them too, so that you can have a featureless bright glarey blob on the screen?

What an immature reaction.

It was serious nonetheless. I'm very passionate on the issue, and it sickens me to even think about how much Celestia is deteriorating. I apologize if it comes across to you as "immaturity".

Passion is no excuse. A passionate person who was also mature might have come up with a more informative and more polite way of showing their passion.

[BobHegwood]

What an immature reaction.

It was serious nonetheless. I'm very passionate on the issue, and it sickens me to even think about how much Celestia is deteriorating. I apologize if it comes across to you as "immaturity".

Ah, what the heck guys...

We're ALL after the same thing here. We want Celestia quality and more
involvement from the Celestia Community. Mr. Chaos (My fellow Limey
friend) does things HIS way and you do things YOUR way.

No problemo guys. You probably noticed that I do things MY way too.

Passionate is GOOD!. Polite respect has it's place too. But some times, you
just get frustrated. Hell, let 'er rip is what I say. Then, at least the
board becomes entertaining for a while. Hee, hee again.

[Fenerit]

Do someone has noted how with naked eye (just quick for not to be blind) the Sun appear black with the except of the border? If this is not a mirage, how does implement it in Celestia?:wink:

Out of topic: Hungry4info, I love your new avatar.

[Ivvi]

Do someone has noted how with naked eye (just quick for not to be blind) the Sun appear black with the except of the border? If this is not a mirage, how does implement it in Celestia?:wink:

Gosh, are you going to look at your monitor so briefly so as not to get blind?
On a serious note, though, I do not think it is possible to be programmed in Celestia due to the lack of the monitor HDR.

[Hungry4info]

...the Sun appear black with the except of the border? If this is not a mirage, how does implement it in Celestia?

I honestly have not observed this. But I've noticed how my eyes see the sun is a lot different from most people here.

Out of topic: Hungry4info, I love your new avatar.

Thanks

[BobHegwood]

Just curious here...

Remember that I'm using Windows Vista, but I'm seeing the Sun's
texture disappear in the center of the body. Let me see if I can explain it
better...

The sun spots themselves actually fade out and disappear briefly when
they cross the Sun's mid-section on my machine and using 1.5 pre3. Is
anyone else seeing this problem?

Does this have anything to do with the atmosphere point raised earlier?
Also, if I install ANY of the modified Sun textures - either Runar's or
Frank's - I see I an orange ball in the center of the Sun. This occurs even
if I use JPG textures for the Sun itself.

Sorry to bother, Thanks.

[selden]

Yup.
It's a bug.

It doesn't seem to happen in the Basic or Multitexture Render paths, jut in the Render paths that use vertex shader codes. (type a Ctrl-V to step through the Render paths)

Also, in the OpenGL2 path with StarStyle "fuzzy points" or "points" (type a Ctrl-S to step through the StarStyles) the whole sun essentially goes white.

I think these problems are side effects of Chris' attempt to implement a simulated High Dynamic Range effect, which didn't work out. I think Chris didn't manage to entirely undo it when it was disabled.