Celestia Forums

Someone knows if a bit of noise would be appropriate to render the comet tails? Something like this (here perhaps too much):

Well, if it's more than 35AU from the Sun, then there should be
NOTHING there. Uh, oh... here we go again.

The only problem I have with the comets is the bright white cap in front. I'm not sure the noise would make it look very good.

I like the noise. It gives more of a "dusty" feel.

buggs_moran wrote:I like the noise. It gives more of a "dusty" feel.

Perso I find too synthetic the actual rendering, I'd like something that change this feeling; why too synthetic? because too regular I think. Now the noise I propose must not being seen as dust (because the particules are too small), but perhaps as perturbations in the tail... Now the question is if this make any sense... (I feel not )

Concerning the corona, perhaps an halo would be nice... (from what I understand, the comet near sun is very bright)

So what we're really looking for is a cloud overlay. Wish I had a clue on how to do that.

buggs_moran wrote:So what we're really looking for is a cloud overlay.

Nope, disagree, it's much too escape smoke!

Can we make it look soething like... say.... this?


You people should know by now I believe Celestia should render objects as they actually appear. How hard would it be to get this in Celestia?

Hungry4info wrote:Can we make it look soething like... say.... this?

Nice shot!

i like the noise , it's the first step in getting them to look a bit more like photos .The grain in the film effect .

One solution might be using different ellipsoids layers so that mathematic ellipsoid shape would not be so obvious thanks to graduated tranparency layers.

Another would be to use a realistic 2d template, rotate it in the
code and render it with sprites like I did it with galaxies...
One could even implement that subtle color profile above...

Bye Fridger

t00fri wrote:Another would be to use a realistic 2d template, rotate it in the
code and render it with sprites like I did it with galaxies...
One could even implement that subtle color profile above...

Bye Fridger

That would be nice! a mix of 2 or 3 template depending on the distance... (glowing halo for the corona, then a first template that will grow slowly (changing it's size) than at a point fading of a 3rd template for the large tail...)

ElChristou wrote:

t00fri wrote:Another would be to use a realistic 2d template, rotate it in the
code and render it with sprites like I did it with galaxies...
One could even implement that subtle color profile above...

That would be nice! a mix of 2 or 3 template depending on the distance... (glowing halo for the corona, then a first template that will grow slowly (changing it's size) than at a point fading of a 3rd template for the large tail...)

O_o So how feasable is this?

Hungry4info wrote:

ElChristou wrote:

t00fri wrote:Another would be to use a realistic 2d template, rotate it in the
code and render it with sprites like I did it with galaxies...
One could even implement that subtle color profile above...

That would be nice! a mix of 2 or 3 template depending on the distance... (glowing halo for the corona, then a first template that will grow slowly (changing it's size) than at a point fading of a 3rd template for the large tail...)

O_o So how feasable is this?

It's just analogous to the galaxy rendering and there it worked pretty well, I would say

Bye Fridger

t00fri wrote:...It's just analogous to the galaxy rendering and there it worked pretty well, I would say ...

Thinking better I'm not sure about the volumetric rendering with billboards... (specially for a face or back view...)

We do want to make comet tails look more realistic, and there are two basic approaches:

1. A sprite based approach, similar to what we have for galaxies
2. A volume tracing approach, like the 1.5.0 Mie scattering atmospheres

The big advantage of the first approach is that it can be made to work with any graphics hardware. A drawback is that it can be tough to hide the fact that the effect is done with billboarded sprites. The second approach can be slow, especially if you want to add realism by ray-marching and sampling volume textures to introduce some irregularities. A hybrid approach would be a sort of hybrid: build realistic looking comet tails from a collection of ellipsoid volumes.

No matter way approach is taken, I think it will be important to consider the effect of forward scattering by cometary dust.

--Chris

1.6? .7?