Black clouds?

[Evil Dr Ganymede]

Here's the code for an oceanworld I plonked around Alf Cen A while testing a texture that Dollan made:

Code: Select all

"Oceanworld" "Alf Cen A"
{
Texture "ocean.jpg"
SpecularColor [ 0.5 0.5 0.55 ]
SpecularPower 25.0
HazeColor [ 1 1 1 ]
HazeDensity 0.3
Radius 8000

   Atmosphere {
      Height 60
      Lower [ 0.43 0.52 0.65 ]
      Upper [ 0.26 0.47 0.84 ]
      Sky [ 0.40 0.6 1.0 ]
      Sunset [ 1.0 0.6 0.2 ]
      # Sunset [ 0.3 1.0 0.5 ]
      CloudHeight 7
      CloudSpeed 65
      CloudMap "earth-clouds.*"
   }


EllipticalOrbit {
Period 1.9462
SemiMajorAxis 1.6
Eccentricity 0.00
Inclination 0.00
AscendingNode 0.0
LongOfPericenter 0.0
MeanAnomaly 0.0
}

Albedo 0.30
RotationPeriod 20 
}


Here's what it looks like. The right-hand region of the planet is illuminated by B.




See the "black clouds" on the bottom right of the planet? Should that happen? This is visible only in the OGL/NVIDIA Combiner path on my card (ASUS 128MB Geforce4 TI4200). If I ramp up the ambient light I can see that the black patches are actually clouds.

Is this supposed to be like this? Is this an effect of the haze or specularity?

[Evil Dr Ganymede]

Not to er, "bug" anyone here, but I am kinda curious about this... are these "black clouds" a problem with Celestia or with the code, or are they actually supposed to look like that?

[hank]

Perhaps ambient light is not being applied to the cloud layer?

- Hank

[Evil Dr Ganymede]

Perhaps ambient light is not being applied to the cloud layer?

There's no ambient light here at all - all the illumination is from the stars. I think the haze might be affecting things...

Hmm. When I turn the Haze off, I can still see the clouds even though they're not illuminated by anything (you'll have to look at it in the dark, it's hard to see in bright conditions)! Maybe that's the problem?



B is the bright star at the bottom right, so that can't be illuminating the dark part of the planet. A is off to the top right, illuminating the bright part of the planet. So why can we still see faint clouds in the dark part if there's no other illumination source?

And again, this is with no ambient light.

[hank]

Your eyes must be better than mine; I can't see anything on the dark side in your latest picture. But the clouds you see are black, right? So they're not being illuminated at all. But you can see them because the surface underneath is being slightly illuminated (otherwise it would be black too, and you wouldn't see the clouds against it). Does that describe what you see?

- Hank

[Evil Dr Ganymede]

Your eyes must be better than mine; I can't see anything on the dark side in your latest picture.

Turn off the lights, cup your hands over the screen to block out the light, and go right up close to it. Or alternatively, manipulate the image in a graphics program - the clouds are definitely there.

But the clouds you see are black, right? So they're not being illuminated at all.

No, they're only black when the Haze is activated in the SSC. In the last picture, the Haze is not activated, and the clouds look white on the "dark side" but they're being illuminated by a dim light source that doesn't appear to exist, because B is on the other side of the planet, visible in the picture.

But you can see them because the surface underneath is being slightly illuminated (otherwise it would be black too, and you wouldn't see the clouds against it). Does that describe what you see?

When the Haze is activated, it would appear that the surface underneath is being illuminated by something and the clouds are not, yes. I notice the effect is more noticeable when I move the viewpoint round the planet so that there's a "dark crescent" - I can see "black clouds" very clearly then.