Celestia Forums

I made a litle modification on Venus because when you aproach the planet you can't see below it's clouds.
So I changed the Venus texture as if was it's clouds and placed another texture for it's real surface...
You can't see much when you go below the clouds because it's too near but makes the planet more realistic


I got the surface texture at this location:

http://gw.marketingden.com/planets/imag ... nusmap.jpg

That's all

Good job...

I did that to Jupiter, Saturn and the rest of the Giants...No ground map so I just used Venus's changing the color a bit....

Well when we can see thier surfaces one day...then I guess we'll know, but until then...

I think them gas giants have a very deep (thousands of km) liquid (hydrogen etc.) surface, but the core itself is solid. The pressure near the solid core is millions of atm.

Again correct me if I'm wrong. I read something like this in a sci-magazine.

No your right The rendering doesn't support true cloud cover just yet...but I'm willing to bet chris will be putting that in...maybe.

There is a real theory expressed in the book "2010" that the core of the gas giants would be a gigantic diamond. Makes more sense that metallic hydrogen (well it does to me, after all carbon's denser).

Now THAT would be something to see.


-Mad Boris

Hi, perhaps I'm dumb, but I can't get it to work. I downloaded the file, placed it in the medres folder, then modified the scc file and added this under "atmosphere", and I also changed the texture file line. It still shows the old texture, and no clouds.

CloudHeight 10
CloudSpeed 0
CloudMap "venus.jpg"

Did you toggle clouds on while in Celestia?

Yes, I have. I;ve found that it works with any of the other cloud .png files like earth-clouds.png or mars-clouds.png. However, I've found that when I apply the venus.jpg as a cloud layer, it does appear, but because it is not translucent, it just covers everything up.

Anyway for me to get around this? I'm guessing here, but I believe it has something to do with the fact that there is no declared alpha channel. I have no idea how to fix that, though.

Oh right, now I understand. I think the problem is that Celestia only does 1-bit alpha at the moment (it's either fully transparent or opaque) instead of a full 8-bit alpha channel. Hopefully full alpha will be added soon. Until then, if you want to see ground below the clouds you'll need to make some transparent windows in the cloud texture...

Ok, I get it. Thanks!

One otehr question. Can I use JPGs for the clouds, or must I use PNGs?

You can use JPEGs for clouds AFAIK, but seeing as JPEG does not support an alpha channel there wouldn't be much point as it would obscure the entire surface texture... : )

Erm.. Ok. I'm using Photoshop. How exactly does one go about creating an alpha channel?

Ortolan wrote:Oh right, now I understand. I think the problem is that Celestia only does 1-bit alpha at the moment (it's either fully transparent or opaque) instead of a full 8-bit alpha channel. Hopefully full alpha will be added soon. Until then, if you want to see ground below the clouds you'll need to make some transparent windows in the cloud texture...

Celestia does support 8-bit alpha channels for files that have them. At least, I see partial cloud transparency with no trouble on my machine.

It's possible that some graphics accelerators might not support 8-bit alpha. In my case I don't have any 3D acceleration at all, so it's not an issue.

You can only create an 8-bit alpha channel if the color format you're using has enough bits to support it-- for instance, a 32-bit PNG (8 bits for each RGB color channel, and 8 more for the alpha). You can't use one with 16-bit color (5 bits per channel and only one for the alpha).

To be realistic, would you not want the venus clouds to be opaque? They basically are in real life and I think it would be cool to go below the clouds and just see an impenetrable blanket over the sky.

I'm going to try this add-on for myself.

Should be cool.

Ciao,
Fleegle

For the venus cloud formation, what are the most realistic settings? I just made some up, namely 100 for CloudHeight (I had it at the ridiculous setting of 5000 just to see more of the surface texture... looks like a shell around a planet -- reminds me of a Dyson Sphere). I set the CloudSpeed to 23 because I like to watch the clouds rotate around the planet.

Anyways, I'd like to set the cloud settings to something realistic... what did you guys use?

-Fleegle

From my Astronomy references, I got theese data for Venus Atmosphere:

Atmosphere height: 60 km
Clouds height (the higher clouds): 50 km
Clouds speed: 94 °/jd (since they rotate around the planet in about 100 hours from East to West, as the planet rotation)
Haze density: 0.4 (it's more dense than Earth's)

I also think that it's not necessary to add an alpha channel to the cloud texture, as the clouds are so opaque that the only way for us to study the surface is using radar telescopes. For an observer on the planet's surface sky would be always dark, or dusk.
regards
Anarion