Earth-Covering clouds

[ben_hamburg]

Hi there,

here is another setup I wanna try, when I have some spare time (which I don´tt right now, hence the post...:

I want to do some realistic earth-seen-from-space-shots. Originally I was considering using Vue for that, but after playing around with the demo I just didn´t feel like learning the package just for those couple of shots...
Also, since I have phoenix at my disposal, I thought I´d give that a try.

1. For the first shot I just need to cover the globe in realistic looking clouds like those:



Is there a simple way to achieve this with Phoenix?

I was thinking something I could simply add a spherical emitter around the globe and add a cloud-texture to it (like the free ones from nasa) and then use that map as an emitter.
I haven´t used mas to emit smoke yet, but its possible, right?
I have no idea with what kind of settings to start with though...do I emit smoke over time or just with a discharge of one frame?
I´m not sure what kind of scale I´d have to use in that shot, but if I can´t model the earth to scale, I´d just multiply the scene scale.
What else would I have to consider to get only very little or no movement in the clouds at all? Would I have to consider gravity or cooling?

2. From there on I´d like to go crazy and have multiple nukes go off...:

https://youtu.be/hKDXaX07APM?t=1m14s

I´d do some separate sims for those or maybe just do one and then instance the grids with a slight time difference.
So far no big deal.
But for increased impact I´m thinking if it wouldn´t be cool to have the nukes effect the cloud layer...I don´t think they´d have to directy interact with the clouds, I was thinking more of having the reaction be triggered by something else.
The easies way would probably be to just have some spheres or cylinders in the same spot as the mushroom and then scale that up, which will push the clouds aside. But is there a possibility to also kind of dissipate the clouds by that dummy? Can I somehow make it emit heat or something like that? it might all be overkill and I might not even use it, but I´m just curious of the possibilities right now...

[ben_hamburg]

Ok, I only had time for some small tests and so far the apporach of emitting from a bitmap doesn´t seem to work. I get the emission , if I use a noise map, but if I use a bitmap I just get equal emission everywhere.
Is this a known limitation of the emission map functionality or am I doing it wrong?

I´d like the simplicity of just using a realistic cloud map for emission but if thats not possible I´d probably go a different route with using several layers of smoke with different procedural noise maps, maybe try out the swirl map.
Might still be overkill If I´m as far out as the reference picture above, but might be worth it, if the camera is a bit closer to earth.

Also still not sure about the scale and testing will require a bit of patience since I think I´ll need quite a high grid resolution for the clouds to look as detailed as in my reference pictures...

[ben_hamburg]

Bitmap emission does seem to work, I´m just not sure how exactly. I tried with simple plane instead of the sphere and a different map and I think the only way it worked was to use the opacity slot on the emitter objects material.
But it also seemed to be reversed (black beeing dense and white beeing no emission).

But also I think trying to simulate the planetary clouds is probably just overkill. I might get some decent results with just using displacement combined with SSS Material and opacity maps for the cloud layers.

Here is what I got with a quickt trial and a little compositing:



I´ll move this thread to the general vray thread for more tips, unless you can think of a solution to do this with Phoenix. The cloud shading would probably look better with atmospheric shading instead of the sss material, but there is probably no way to render a displaced mesh as a phoenix atmosphere, right?

[Svetlin.Nikolov]

Hey,

Are you using a nightly? Can you try a latest one because we did some fixes to the source emission and there should be no more issues there with mapped discharge. If you still have problems, it's the ideal time to get rid of any source issues once and for all

You can not transfer a displaced mesh to an atmosphere, but you can displace the atmosphere, so I guess if you use the mesh as a brush emitter and then add the displacement at render time, this could be the solution.

You could also check the Clouds Quick Setup preset as to how you could approach the discharge, especially if you want a moving cloudscape - it discharges based on an animated 3D noise map and constantly brushes a small amount of smoke, also adding some turbulence and some wind in order to give more life to the clouds. In any case, you'd need huge resolutions, so you might want to use several simulators.

Point 2 is achievable as well I think, but for some point we might better add or refine the existing features so the workflow can be easier. We can get into more detail once the basic scene setup is done and working

Cheers!