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View Full Version : 3d Fluid Container (not so fluid anymore)... skipping frames in preview and render


klaz
12-14-2010, 04:21 PM
Hi all,
I am trying to create a fireball kinda using a simple sphere as an emitter within a 3d fluid container. I have made several tests in empty scenes and managed to get a look i like. Having set up my scene now with the proper scale I found out that it does not work as it did (even with the same settings). Basically the result is not a flowing trail of smoke, but instead some blobs, as if it is skipping the rendering of some (in-between) frames. After several tests with size and resolution of the fluid container I have concluded that the problem is the actual emitter (sphere) moving too fast. However even if i increase the 'simulation rate scale' it does not seem to help. Are there any settings I have missed or any rules about fluids I have not followed?

I found that by changing the playback in the preferences to play every 0.1 of the frame, the fluid calculates as it should roughly. However this is not a real solution as i will be rendering out every frame and not any sub frames. An alternative would be to render eveything twice the frames (48fps or faster) and slow it down later on manually. This could be a solution but i doubt its the right/efficient way to go.

If you have any ideas or advice in solving this problem I would be grateful.


Here are some test renders to show you what i mean by not having a flow anf looking like blobs. One is a low rez and the other quite high. Also with simulation rate scale to 10 already. The sphere is moving from right to left.

http://fluidtest.weebly.com/uploads/9/3/5/0/935032/low_rez.jpg


http://fluidtest.weebly.com/uploads/9/3/5/0/935032/high_rez.jpg

Derek Wolfe
12-14-2010, 05:41 PM
Try caching out your fluid with a sample rate of 10. This will solve 10 subframes, the same as setting your playback to 0.1. Then you can still render the correct frame range.

gramulho
12-14-2010, 06:22 PM
Try also enabling Motion Streak under your fluid emitter.

Maya has problems with fast moving emitters on fluids, you should do a search here, it has interesting topics with tips & tricks about it.

klaz
12-16-2010, 10:17 AM
hey guys,
thank you for you replies.

I have tried the cache idea and it basically works. That is good news but is it sooo slow.
gramulho, I am using maya 2009 SP1 and cannot find this option, so i assume this is only in 2011 as i have seen it there.

I will try to make the container 5-8 times smaller (out of 10 lets say only in Z as i need it to be very long) originally, and once i set the look i will extend it trying to keep the same resolution but higher to accommodate for the extra length in Z. Will that work or once i extend it the look will change?
eg lets say i need the fluid size to be 100x100x10000. I will originally make one 100x100x200 with rez 100x100x200 and once i get the look i extend it in Z and increase the rez in Z x5.

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12-16-2010, 10:17 AM
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