Le 18-11-12 à 22:35, Bald Eagle a écrit :
> I think perhaps there's no reason one has to stick to a static construct with
> the only change being the camera location.
> 
> Since for every animation frame the scene can change, perhaps the way to do it
> in one shot is to dynamically adapt the media density to what that frame
> requires to achieve the desired look.
> 
> So graph out what you want in terms of visibility, and then based on the
> distance between the camera and the planet's surface, change the density to fit
> your needs at that instant.
> 
> Similar to what others have proposed, you could define your visibility as a
> spline, interpolate, and use the camera distance to the planet to index a
> density value.
> 
> There's probably other ways to do it, but I'd say the first step would be to
> story-board out the animation and use that as a guide to define very detailed
> requirements for key points in the animation, and then see what the best method
> to transition between those points is likely to be in terms of time, complexity,
> and quality of end result.
> 
> Just my take on how I'd likely approach this.
> 
> 

If you don't want or need the media to stretch down to the ground, but 
stop at some altitude, you can have a difference of two spheres.
The outer sphere will determine the top of your cloud layer, and the 
inner sphere will prevent the media from going to low.

With that approach, you can use the onion pattern scaled to the distance 
between the two spheres, and use the phase option to shift the pattern 
if needed.

Next, you can use some alternative wave type, like triangle_wave, 
sine_wave or scallop_wave, to help fine tune the density gradient.

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Hi again!

Well, I still don't know exactly what I had wrong because I tried so many
variations, but it works now...

Thanks to everyone who spent some time on my problem :-)

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Hi again,

I found the culprit! I was actually doing something wrong, but it wasn't related
to the media density at all.

My problem was simply a "samples" set way too low. I cranked it way up and I now
have a very smooth and satisfying result.

The (big) downside is the rendering time, though. But you can't win them all...

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Le 18-11-30 à 10:20, Shuffle a écrit :
> Hi again,
> 
> I found the culprit! I was actually doing something wrong, but it wasn't related
> to the media density at all.
> 
> My problem was simply a "samples" set way too low. I cranked it way up and I now
> have a very smooth and satisfying result.
> 
> The (big) downside is the rendering time, though. But you can't win them all...
> 
> 
Did you play with intervals ?
Keep intervals at it's default of 1, and better yet, don't use the 
intervals key word at all.

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On 30-11-2018 21:42, Alain wrote:
> Le 18-11-30 à 10:20, Shuffle a écrit :
>> Hi again,
>>
>> I found the culprit! I was actually doing something wrong, but it 
>> wasn't related
>> to the media density at all.
>>
>> My problem was simply a "samples" set way too low. I cranked it way up 
>> and I now
>> have a very smooth and satisfying result.
>>
>> The (big) downside is the rendering time, though. But you can't win 
>> them all...
>>
>>
> Did you play with intervals ?
> Keep intervals at it's default of 1, and better yet, don't use the 
> intervals key word at all.

...and with a bit of testing you can find what the lowest acceptable 
sample value could be for your scene.

-- 
Thomas

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Alain wrote:
> Did you play with intervals ?
> Keep intervals at it's default of 1, and better yet, don't use the intervals key
word at all.

I did set it at 1 since I use method 3 and I read (here, last line:
http://www.povray.org/documentation/view/3.6.2/421/ ) that's what one should do.
But thanks for the tip ;-)

Thomas de Groot wrote:
> ...and with a bit of testing you can find what the lowest acceptable
> sample value could be for your scene.

That's right. But I will actually set it dynamically along my animation frames
because the right value for out-of-atmosphere is about 500 while deep in the
atmosphere is already good with 20 or so. Thus setting it dynamically with a
function of the altitude will greatly reduce the overall rendering time.


Thanks for your help!
It's great to see that POV's community is still so active after all these years
(I first played with it more than 10 years ago). Keep it going! :-)

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