Water Blast/Explosion

[Facu961]

Hi!
I want to create an explosion coming from a river. I've shot the river plate, and now i want to make the explosion sim to compose it. How would i make such effect? How do i make water come out of nowhere so that then i can place it over the plate?

[ChristianZ]

Something like this?
https://youtu.be/p9E68QRSCWw

[Facu961]

Like this

https://www.youtube.com/watch?v=jeD9FMrZQsY

And then how should i composite the displacement of the water after it falls, over the real river footage?

Thanks!

[Facu961]

Something like this?
https://youtu.be/p9E68QRSCWw

Like this

https://www.youtube.com/watch?v=jeD9FMrZQsY

And then how would i composite over the displacement that the falling water would cause?

[Facu961]

Something like this?
https://youtu.be/p9E68QRSCWw

Sorry, like this

https://www.youtube.com/watch?v=jeD9FMrZQsY

[ChristianZ]

Ok, I see. I think it is helpful for the integration of the blast into real footage to let the explosion come out of a plane of water which is already there. In this way you see better the reaction of the surrounding water to the explosion. Your example https://www.youtube.com/watch?v=jeD9FMrZQsY is showing nice explosion features, but it might be less easy to integrate in a video later. So in this case I would work with 2 emitters and an attractor with negative force and keyframed power.
1) prepare the water surface using a fill object emitter inside an open box
2) place a circle emitter below the surface of the water with side emission turned on
3) place the attractor below the water surface and maybe an additional circle emitter to shoot up in the air
4) play with keyframes of the attractor force and emitter settings, all at low resolution so that you can test many parameters
5) render the scene in your 3D program, with mesh for the standing water and particle rendering for the fountain

Further settings for the compositing depend on your software to do that.

[Facu961]

Ok so i made the blast. How should i mesh it and later compose it?

[ChristianZ]

You can mesh the blast particles but the files will be really big and slow to calculate if you turn most particles into a polygon mesh. That is why most people use particle rendering (point rendering) instead of meshing for fountains or water blasts.
Something like this: https://youtu.be/G-JO-a3MiQ4
How to do it depends on your render engine in your 3D program. There are some specialized render engines such as Krakatoa which render particles very fast. In other programs you will have to render the particles as little spheres. The so-called "RF render kit" by Nextlimit is a plugin for some selected render engines. Maxwellrender also includes options for rendering particles.
The standing water or ocean can be meshed to show the surface and the disturbance by the blast.