gillsp Posted July 24, 2014 Share Posted July 24, 2014 Hi, I have a scene that a crack exists, so dust needs to emit from it. Right now my approach is using pyro, however, I am not able to emit only a few frames of dust(kinda like when you kick off the ground the dust only exists on the second that you contact, then it fades off). I tried animating the source temp and density(keying 0 to 1 to 0) and it looks like it pops up and then disappeared. They don't look natural. Any suggestions? The other way to do it is with particles, which might be easier, but some day i will run into these problems again. Any help is appreciated. Quote Link to comment Share on other sites More sharing options...
Guest frostbite Posted July 24, 2014 Share Posted July 24, 2014 If you can attach your example file, I can take a look at it. I have done a similar kind of effect before. -frost Quote Link to comment Share on other sites More sharing options...
portdusk Posted July 24, 2014 Share Posted July 24, 2014 I am not able to emit only a few frames of dust(kinda like when you kick off the ground the dust only exists on the second that you contact, then it fades off). I tried animating the source temp and density(keying 0 to 1 to 0) and it looks like it pops up and then disappeared. Please post your hip file. The simplest way to get a puff of dust would be to keyframe your "activion" parameter on your DOP sourceVolume node. If you're animating the density parameter on your smoke object, then you're really just changing the way the data is displayed in the viewport. Alternatively, you can just have less density and temperature in your source geometry. If your source has a density of 0, then adding that into the sim will have no effect. Quote Link to comment Share on other sites More sharing options...
gillsp Posted July 25, 2014 Author Share Posted July 25, 2014 Sorry, please see attached files FxCrackv4.hipnc Quote Link to comment Share on other sites More sharing options...
portdusk Posted July 25, 2014 Share Posted July 25, 2014 Well first off, your size is way off, like 2 orders of magnetude off. Your smoke volume size is 26 cubed. Houdini's units are meters, so you're looking at a dust puff that is 8 stories tall. You've also got every single noise setting enabled. I'd recommend resizing your sim to real-world scale and disabling all of the 'shape' parameters. First just focus on your source and getting that to start and stop when you want. Add noises one at a time after you've nailed down the initial shape and timing. Quote Link to comment Share on other sites More sharing options...
gillsp Posted July 25, 2014 Author Share Posted July 25, 2014 Well first off, your size is way off, like 2 orders of magnetude off. Your smoke volume size is 26 cubed. Houdini's units are meters, so you're looking at a dust puff that is 8 stories tall. You've also got every single noise setting enabled. I'd recommend resizing your sim to real-world scale and disabling all of the 'shape' parameters. First just focus on your source and getting that to start and stop when you want. Add noises one at a time after you've nailed down the initial shape and timing. Hi, thank you for the quick reply, do you mean the fog itself, or the crack? Because there were 2 pyros in the file, one is supposed to be large scale fog and the other is supposed for dust. If you mean the dust is 8 stories tall, then I am really way off. Quote Link to comment Share on other sites More sharing options...
portdusk Posted July 25, 2014 Share Posted July 25, 2014 there were 2 pyros in the file, one is supposed to be large scale fog and the other is supposed for dust. If you mean the dust is 8 stories tall, then I am really way off. I would really recommend against having mutliple, separate sims in one object level dopnet. I would suggest having separate SOP-level dopnets for each of your sims. So you have a geometry OBJ node called 'fog' and inside of that you have a dopnet that only contains the fog sim. This helps to keep your dopnets clean, and your sims efficient. It's also easier to reference all of your source nodes if they're just ../../ If you remove the 10x uniform scale, you'll be at a better scale for your sim. Sorry I can't post an example file. :/ Quote Link to comment Share on other sites More sharing options...
gillsp Posted July 26, 2014 Author Share Posted July 26, 2014 Hi, I kind of got what you are saying,. I did find out the solution. However, your suggestion leads to my next question, is it really important now as of the real-life scale? I think right now 4 grid squares means 1M X 1M, please correct me if I am wrong. But if I do a simulation of a candle, that puts it really really tiny in the scene. I do understand like for real production and all that it really matters, but what about like a fireplace, or a candle with fire that I just mentioned. Also, what should be a good resolution for such scale? Like for reference, 1 cubic meter should have a Max axis at 100.(I'm more used to the max axis reverse the resolution like 0.1 or something), Sorry for so many questions, I appreciate your help Quote Link to comment Share on other sites More sharing options...
portdusk Posted July 28, 2014 Share Posted July 28, 2014 is it really important now as of the real-life scale? I think right now 4 grid squares means 1M X 1M, please correct me if I am wrong. I always sim at real-world scale. All of your forces default to real world scale, and if your sim is scaled up 10x, then your movement will not look correct. I can't tell you how many grid lines represent one meter, but one unit in houdini is one meter. If you middle mouse on your node, you can see the xyz size of your geometry. Just looking at your smoke object I saw that the intial bounding box was 26^3 which means it's 26 meters on each size. But if I do a simulation of a candle, that puts it really really tiny in the scene. I do understand like for real production and all that it really matters, but what about like a fireplace, or a candle with fire that I just mentioned. I would suggest bringing down the size of all of your other elements to real-world scale as well. Your scene scale also determines other important factors in rendering like motion blur and depth of field. what should be a good resolution for such scale? Like for reference, 1 cubic meter should have a Max axis at 100.(I'm more used to the max axis reverse the resolution like 0.1 or something), Sorry for so many questions, I appreciate your help I personally don't ever use max axis, because with a resizing bounding box, you can't be sure the resolution will stay consistent. I always use division size for my fluid sims. As for what size, it really depends on the type of simulation and how it's going to be rendered. General rule of thumb is that you want 0.5-1 voxel per pixel. So if you're rendering a candle and the flame is 900 pixels tall and 300 pixels wide on screen, then you'd want a sim that's around 150x450x150 (assuming the z-sixe of the candle is the same as x). That's a total of 10,125,000 voxels. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.