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Pyro sim drastically changing in higher res


thhonda

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Hey everyone!

I recently started following Steven Knipping's series of tutorials, and I'm getting some issues whenever I try to increase the resolution of my pyro sim.

When it's low res, everything goes fine. If I increase the voxels amount, the sim goes crazy and the explosion gets huge.

 

I made a quick search and found the "Up-res Container", but couldn't make it work. Anyone has any suggestions on how to increase the resolution of my sim without changing it too much?

 

Thanks in advance!

dynamics_V.v02.hiplc

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Up res instruction on first page here

dont make the difference between low/hi too much. Dividing your division size by two for hi res is a good range

but if your sim explodes there's something wrong.. increasing resolution should make it smaller

 

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I have exactly the same issue, and i was wondering how often the "Gas upres" node is used comparately at the simple division size setting. 
I mean, does the fx artist which works in studio use the division size to make the sim in high resolution or does he use the Gas upres node ?

 Because in my mind (certainly wrong idea), the upres workflow was "obsolete" ?

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Most people just use division size. Up res is a extra step and it's not needed. But it allows you to run a lot of iterations and get them reviewed in daily's. Then you can up res and not worry about it looking different then what your supervisor approved. And you can add high frequency details. If your using dop forces or anything slowing your sim you can bypass having to calculate them at high res.

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OK Yon, Thanks for your reply. I will have a look to this "upres" workflow, because the "division size" setting blow my sim.
Is there a relation between division size and "gas released" parameter ? because when i increase the resolution my sim changes like if there was too much gas released in the combustion.

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6 hours ago, Yon Anadeyo said:

Up res instruction on first page here

dont make the difference between low/hi too much. Dividing your division size by two for hi res is a good range

but if your sim explodes there's something wrong.. increasing resolution should make it smaller

 

Thanks @Yon Anadeyo, I'll take a look into that! I'm gonna also rewatch carefully the tutorials, because the first time I followed it I didn't have this issue.

 

@marles I'll let you know if I figure something out!

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Upres is the way to go, and no it's not obsolete IMO, but currently the of-the-shelf upres is a bit broken in some places.
If you undertand DOPs a bit, it's an easy fix.
- most of the lowres fields imported have the wrong type, eg: lowresdensity should be a Scalar field, not Vector
and I would use the border type "Constant" for all fields, not "Streak"
Also you should toggle on "Use Lowres Source Resolution" and "Source From Imported Fields" to get results that
match your lowres as much as possible.

Edited by bunker
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On 2017-5-2 at 0:04 PM, marles said:

Personnaly, to avoid the messy flowing of my pyro sim, un reduce the gas released. But tha'ts not a good deal i think.

Hey @marles!

I shoot Steven Knipping an email (I didn't send the file, just made a brief explanation of the problem) and here's what he replied

"Indeed, try to reduce the gas released by the same factor that the resolution was increased! Surprised there is such a huge difference in your sims, but it's worth a shot.

Sounds to me that in your case there are ignition areas that are not being sufficiently represented with the lower resolution, that suddenly become factors with the better resolution. You're also right that the up res can be used if it's very important to be able to more accurately predict the final shape from a low res sim."
 
And thanks for the tips @bunker! I ended up not using the Up Res, but I'll make sure I follow them if I have to!
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