Rocket Burn

[BenOC]

I'm hoping someone can help me out with this.

I've been trying to get a decent rocket burn for many days now without much luck. What I'm wanting to do is create a burn like the photo attached that is shaped like a tear drop and looks like it is burning very fast instead I end up the other image or something similar/worse....

I've changed a multitude of settings but still can't seem to come close (as you can see).

I want to have the least amount of smoke as possible but I still need to have a alpha channel to composite this in AE which is also causing headaches.

Here is the link to the 3ds max shot I'm working on if anyone has the time to point me in the right direction?

https://www.dropbox.com/s/wqrm90w8g6...wn_01.max?dl=0

[Svetlin.Nikolov]

Hey, there is a jet flame example scene here in the forums - it's not the same thing, but the principles of simulation and shading are pretty close - look it up and I hope it would be a good starting point.

In order to get that smooth shape, you would need a lot of steps per frame - 10-20. Also, you might need a bit higher conservation quality than the default - at least 30-50. The shape of the nozzle would also matter a lot for this shot, and also keep in mind that the final shape for this kind of sim won't be governed only by the simulation, but also by the render settings, which you can use for altering the color and opacity in order to thin out the jet and make it more opaque and more red away from the nozzle.

As for comping, maybe go with Use Own Opacity or Use Smoke Opacity fire modes: https://docs.chaosgroup.com/display/.../Render%20Fire. We have a tutorial for comping fire/smoke that might also be interesting to you: https://docs.chaosgroup.com/display/...Fire+and+Smoke

Cheers!

[BenOC]

Thanks for that info and I appreciate the help.

Unfortunately I've already seen those suggestions and tutorials, some made by yourself like the rocket tutorial. I have spent close to 8 hours just looking at tutorials and files with a lot longer (over 30- hours) creating sims, changing settings or trying different emitters without coming close to the effect shown in the image above.

I have managed to comp shots and get some OK results with smoke (see link below) but I need to create in-space shots. I've saved the Jet file and had a crack at getting it to work but once I merge it into my scene I cannot get the fire to display?

https://vimeo.com/370821630

It also doesn't have the teardrop flame, coloured in order from the nozzle, blue to white hot fading to red (like the photo above) used by a lot of new rocket propulsion systems today.

If you can give me an idea of the correct emitter/object shape that would at least start me off in the right direction.

Cheers

[Svetlin.Nikolov]

Ah, is this how your shot should look like? This would be tough once we get the jet shape and shading correct, because the jet will need more steps per frame in order for the solver to keep up with the high fluid velocity so it can become smooth, and at the same time the smoke always looks best with as few steps per frame as possible because more steps will smooth and blur it out.

Let me give a shot at getting the jet shape and shading as in the ref and will ping you again...

[Svetlin.Nikolov]

Ah, also - if I just get the scene you attached and merge the jet flame scene into it, would I get the same issue you are getting with the fire not showing? Is it only a preview thing, or it does not render?

[BenOC]

Yes, merging the Jet scene into my scene was not working. Scaling issues maybe?

I recreated as many of the jet settings over the past couple of hours and have a fairly nice result after some trial and error.

Unfortunately still cannot acheive the tear drop effect, as you say it will be very hard to do. Finding the right shape for the emitter looks to be the hardest part. On top of that choosing the right Conservation method and Quality and possibly introducing Classic Vorticity (from my limited experience).

Here is the working file if interested:

https://www.dropbox.com/s/yjj2gzrex4...ne_01.max?dl=0

[BenOC]

More time spent on this rocket burn. Looking a little better with a slight tear drop effect.

I'm getting this stepping effect in the bottom third of the flame, any idea's on how to smooth this out, more steps or Conservation Quality?

[Svetlin.Nikolov]

Hey, was just checking the merging issue. Not sure if I got the same thing as you, so just making sure we are on the same page:
- I am merging this scene: https://forums.chaosgroup.com/forum/...537#post999537 into the one from your post from yesterday, and NOT into the one from the first thread post.

After merging, the path to the cache files will be disconnected - by default the caches go into the $(scene_path) directory under the Output rollout, which is by default next to the max scene. So when merging into a new scene, the merged simulator will no longer be able to find its old caches next to the original scene, and you gotta let it simulate new caches. This happens so that you don't overwrite the cache files from the original scene if you start a simulation from the merged one. The cache paths are only preserved if you xref objects into your scene - in that case, if you merge these objects into the scene later, they will point to the original cache path.

However, I found an issue where if you merge a simulator from a scene with different scene scale into a new scene, the grid resolution of the merged simulator changes automatically and in this case it becomes several hundred million voxels. So this is something that we gotta fix.

Another thing regarding the shape of the flame - in the jet engine scene there are several simulators with different emitter shapes, so maybe you were looking for a shape closer to the second simulator - however, your scene is looking awesome now!



Indeed, the stepping could be removed by increasing the steps per frame, but since you are already at 20, maybe try the smoothing options from the Input rollout instead?

Cheers!