Multiple systems too bright from a distance

[Malenfant]

Since the barycentres were added a few versions ago I've noticed this problem - if you have multiple stars in a system and go far away from it then the "star" formed when the individual stars merge looks a heck of a lot brighter than it should be. It looks like the brightness of the lens flares of each star may be overlapping and adding to eachother.

But right now, I've got 5 stars in the Spica system and as a result it looks a lot brighter than it should be when seen from Earth, which is wrong. I've show this in the picture below: on the left is Spica without any extra stars, and on the right is what it looks like from the same vantage point (near Sol) with the extra stars there.

[ElChristou]

Yep, I've noticed this issue too...

[phoenix]

well I have no idea what is realistic in this scenario but I find it logical that 5 suns beeing very close together are much brighter than any single star out there.
of course only if there combined brightness is big enough

[selden]

phoenix,

I think the point is that we know the combined luminosity and the individual luminisities of the stars in a given multiple star system from observation.

If we place the individual stars with their known individual luminosities in Celestia, together they should produce the same apparent luminosity on the screen as a single star that has the same luminosity as their observed combined luminosity.

Of course, one should use a known multiple star system with measured luminosities to do the test. (Or several, perhaps, testing systems with different colors.) There's always the possibility that one's own arithmetic has errors if one constructs a star system from scratch.

[Malenfant]

well I have no idea what is realistic in this scenario but I find it logical that 5 suns beeing very close together are much brighter than any single star out there.
of course only if there combined brightness is big enough

No, this is definitely a flaw in Celestia's handling of multiple systems. As Selden says, we know the magnitude of multiples from observation... but this isn't really anything to do with that - you can't get a reading on the magnitude of the combined system using Celestia, only of an individual star in the system.

I'm pretty sure that the problem is related to the way the star flares are added within the program - those are what's making it look brighter, since from a distance all you'd see of the entire system is a one-pixel dot.

[phoenix]

did you try switching the star rendering mode pressing "ALT + @" (only available in the cvs-version)

[Malenfant]

did you try switching the star rendering mode pressing "ALT + @" (only available in the cvs-version)

There is no "@" key on my keyboard. Do you mean ALT+2 (2 is where the @ sign is)? If I do that I just get an error noise.

[t00fri]

did you try switching the star rendering mode pressing "ALT + @" (only available in the cvs-version)

There is no "@" key on my keyboard. Do you mean ALT+2 (2 is where the @ sign is)? If I do that I just get an error noise.

Phoenix was incorrect! The star rendering switch is

SHIFT + 2 = @

[phoenix]

did you try switching the star rendering mode pressing "ALT + @" (only available in the cvs-version)

There is no "@" key on my keyboard. Do you mean ALT+2 (2 is where the @ sign is)? If I do that I just get an error noise.

Phoenix was incorrect! The star rendering switch is

SHIFT + 2 = @

yes and no.
on my computer star-rendering switch is "ALTGR + Q" = @ (those bindings always confuse me)

I suppose that's platform dependent wherever your @ is binded to.

[t00fri]

did you try switching the star rendering mode pressing "ALT + @" (only available in the cvs-version)

There is no "@" key on my keyboard. Do you mean ALT+2 (2 is where the @ sign is)? If I do that I just get an error noise.

Phoenix was incorrect! The star rendering switch is

SHIFT + 2 = @

yes and no.
on my computer star-rendering switch is "ALTGR + Q" = @ (those bindings always confuse me)

I suppose that's platform dependent wherever your @ is binded to.

The switch is @. Since you were talking to Malenfant who uses an US English keyboard, @ = SHIFT +2 for him. That's what would have been the correct answer and that's what I wrote.

Bye Fridger

[Malenfant]

Well, either way pressing "@" seems to make no difference to anything at all. I've tried it in every star rendering mode (points, fuzzy points, and scaled discs) and pressing @ did absolutely nothing.

That said, remember I have a 1.5.0 executable that Chris made for me on 8th Sept. Maybe someone with the latest full version can try it?

[selden]

The new HDRI code has been in CVS for a very long time, so it should be in the version you have. You might try phoenix's copy of the current CVS binary (a link is in his sig).

It only gets applied when you're far enough away from an object. And it has bugs. (e.g. it doesn't fade gracefully into the standard view.)

Here's what it looks like when you're the right distance from the sun. (shift-2 scaled discs)



Here's the same view without hdri enabled ( scaled discs)


Here's the same view with just fuzzy points




Here's a URL to take you to this viewpoint.
Blazing Sun

You still must toggle HDRI (shift-2) and star-style (ctrl-s). URLs do not (yet) include those settings, although they are recorded when Celestia exits. This can be a confusion factor, since HDRI doesn't announce itself. You can't tell if it's on or off unless you recognize its effects, which are only visible at certain distances.