Smoke Sim - Smoke Rendering is Jagged/pixelated

[MarioRothenbuehler]

Hello everybody

I have a problem with a smoke simulation regarding the rendering of the simulation ( I Render in Corona), which I can't solve despite of searching and I hope that someone can help me.

I reused an old Simulation wich was working an rendering fine, the details were crisp. In Low Resultion the new Result looked good as well. But when we were Rendering in High Resultion we saw that the smoke Sim looks Jagged and pixelated on the edges.
The main difference between the two is found in the volumetric option. In the old Version we used constant color. But we need the new sim to have a colorgradient to look as wished by the client.

I tried the usual like increasing the grid resultion (did not change at all), increasing steps per frame ( changed the look of the whole simulation), changed scene scale from 1 to 0.1 and 10 (also no change depending the problem)
Both attached screenshots are taken at 100% Scale.

Any Idea or Help to solve that issue is warmley welcome

Best Regards

[MarioRothenbuehler]

Of course this Post should have ended up in the according Phoenix FD :: Issues Forum ... Sorry for the misplaced post!

[Svetlin.Nikolov]

Hey,

Definitely try the Spherical Sampler under the Rendering rollout (https://docs.chaosgroup.com/display/...moke+Rendering). The look you are getting in the image to the left looks exactly like using Linear Sampler.

In the image to the right, I see something different though - seems like your smoke opacity cuts off very early and leaves and edgy look. You could decrease the Minimum Visible Opacity even below 0.001 in order to get more of that detail back.

Beware that both these changes will increase your render times somewhat.

Cheers!

[MarioRothenbuehler]

Hi Svetlin
Thanks for your input. We've switched to Spherical Sampler. The result looks better now but still not sharp. For the single shots we can live with the result.
As for the Minimum Visible Opacity... ...we can't input a value as low as 0.001. So the value jumps to 0.

We've updated to PhoenixFD4 and Vray Next.
However, this setup is causing problems. We have a lot of crashes and rendering with Corona 5 is not possible at all.
I have already written to Georgi Zhekov.
Are there known problems with PhoenixFD4 and Corona 5?
Thanks for your answer in advance.

/.mario'

[Svetlin.Nikolov]

Hey,

Sure you can input a value below 0.001 - it's just a Max setting that by default it won't show you the actual number you've input if something's going on after the 3rd decimal digit. You can change this from 3ds Max's preferences and make Max display more than 3 decimal places. However, even if you don't change the display of fractional numbers, if you type in 0.0001 and render, you will see the value holds and would be used - it just won't be displayed to you.

Yes indeed, Corona still has not added support for Phoenix 4. We are hoping there will be a new compatible version soon, but until then you have to either revert Corona to a version pre-5, or revert Phoenix to a version pre-4.

Hope this helps!

[Svetlin.Nikolov]

Ah, as for the sampler - generally grid artifacts would tend to reveal when you are looking straight at the grid axes. So if you rotate the grid or the camera a little to the side, this should improve somewhat. Also, if the simulation is not too long to redo, note that it's not a problem for Phoenix to simulate with an inclined simulator, so you could workaround it this way as well. If such artifacts are not cleared out with the Spherical sampler, however, note that this is a sign that the grid resolution might have been reduced too much. How many voxels do you have in this grid?