Far better atmosphere definition for Earth!

[JackHiggins]

Hey all

This is something that has been annoying me for a while now- so I fixed it! A few versions ago, the colour of the earth's atmosphere was corrected from lavender to blue, it's proper colour. (People may remember the topic) However, there was never any mention of the distinct hard line between the surface of the earth and the atmosphere itself. This doesn't happen in real life, because there is so much "sky" between you and the far horizon, it's blurred out. (Faraway hills are blue... )

So, while trying out some 32k bluemarble stuff in the latest 1.3.1pre, I decided to finally fix the Haze definition for Earth. Observe!

Before:


After:


Pretty big difference huh? (It looks more realistic with clouds, but they're turned off to just show the haze effect)

This is the new definition i'm using:

Code: Select all

   HazeColor [ 0.43 0.52 0.65 ]
   HazeDensity 1

(The colour is the same as the "lower" colour for the earth's atmosphere)

Another comparison: (left hand one is standard earth texture- middle is normal bluemarble dds, right is new haze definition.


Whoever is in charge of maintaing the solarsys.ssc file on the CVS tree should really change this, as it looks much more realistic this way. The same could be done for all other planets with atmospheres, just set the strength to 1 and the colour to the lower sky colour!

================

On another note - I just saw the ISS fly over! I've seen it 3 or 4 times in the last week, but it still looks great every time!

[HankR]

Jack,

Your new haze definition looks great. Nice work!

BTW, I also enjoy watching the ISS pass overhead. One night last July I managed to see it on 5 consecutive orbits (didn't get much sleep that night). My two favorite sightings are the one that I wasn't looking for (just happened to spot it and later verified the sighting time) and the one where it passed over in formation with the space shuttle (the two were separated by about fifteen degees or so).

- Hank

[Rassilon - not logged]

There is one small setback with a haze density of 1...This makes everything on the surface blue...Maybe this can be fixed in a later version of Celestia...

FYI is all...

[granthutchison]

Dear me. I'd really need to have my arm twisted by mass demand before I made that change. Or am I the only person who thinks that it looks absolutely horrible?
Jack, I agree the sharp horizon is a defect at present, but haven't you bought a good horizon effect at the expense of making the nearer Earth surface look like it's submerged in the worst smog imaginable? That washed out blue cast to the whole landscape looks nothing like the images from orbit that I've seen.
Show of hands?

Grant

[t00fri]

Dear me. I'd really need to have my arm twisted by mass demand before I made that change. Or am I the only person who thinks that it looks absolutely horrible?
Jack, I agree the sharp horizon is a defect at present, but haven't you bought a good horizon effect at the expense of making the nearer Earth surface look like it's submerged in the worst smog imaginable? That washed out blue cast to the whole landscape looks nothing like the images from orbit that I've seen.
Show of hands?

Grant

Grant,

twisting my arm would not be enough;-).

Bye Fridger

[granthutchison]

Jack:
Sorry, I wasn't aiming to be offensive above, and I apologize if it comes across that way. But blimey, your pictures gave me a hell of a fright!

Grant

[chris]

I rewrote the atmosphere rendering code for 1.3.1 in order to make atmospheres work for elliptical planets and eliminate the unrealistically dark shadows on objects in the daytime sky. But, I'm still somewhat unsatisfied with the appearance of atmospheres, the sharp transition at the horizon being the most objectionable feature. Setting the haze density to 1.0 mitigates the effect, but at the cost of making Earth look terrible away from the horizon.

The fundamental problem is that haze is a big hack.
Celestia handles haze and atmosphere haloes completely independently of each other, when they're really the same phenomenon--scattering of light by atmospheric gas and dust. My 1,3,2 rewrite of atmospheres will use physically based calculations (no doubt with a few *ahem* 'empirical' terms) in a single model that handles both haze and haloes. The sharp horizon will disappear. The overhazing at low altitudes will no longer be a problem. And you'll see a nice skyglow around the sun. The HazeColor and HazeDensity fields will either be ignored, or will have a slighly different effect on the appearance of planets--I still have to work out the details.

--Chris

[JackHiggins]

Aww...

I think it looks really good!! Doesn't matter though- everyone has their own opinion! (At least Hank believes in me... )

...and the one where it passed over in formation with the space shuttle (the two were separated by about fifteen degees or so).

ooh... I'd love to see that- when's the next shuttle flight due- next april sometime isn't it?

Grant, Fridger,
Glad you liked it... We can expect this in 1.3.1 final so yeah? I'll be waiting...

Chris
That sounds great- can't wait to see it!
btw- any rough date for a 1.3.1pre final release yet...?

[Rassilon]

Jack,

Try using a haze density of 0.5...Its the standard density I use for all my worlds...

[JackHiggins]

Rass

That doesn't fix the problem of the sharp horizon (you can still see it...) What I was looking for was a gradual transition to completely sky colour- which is what a density of 1 does... Doesn't matter though now that I know there's something much better coming!

[Don. Edwards]

If everyone would have a look at some of my earlier pictures of my 32k texture scaled down to 16k to what it looks like in Celestia you will see that I too made some adjustments to the haze settings. But in the process of building the new cloudmaps I discovered that the blue haze setting was making the ice at the poles to blue and it made the clouds look darker than they should. But by setting the haze back to the standard [ 1 1 1 ] setting corrects this problem. So keep in mind that changing the haze may have a few beneficial effects it can and will cause negative ones elsewhere in the rendering. Trust me I have been playing with this for months now.

Don. Edwards

[Don. Edwards]

Ok, This is just a quick example of what my haze setting looked liked. It had a major color shift for the oceans as well as a slight blue haze effect on the land. I think its to much though. The texture is the new 16k.


Don. Edwards

P.S.
Sorry no thumbs this time.