loopyllama Posted August 16, 2009 Share Posted August 16, 2009 (edited) This explosion is an upres sim of 200 divisions (the low res sim was 50). Thank you for the nice shader video Mario! I had a tough time dealing with the integration of the smoke and fire. In Mario's video he erodes away the smoke surface with noise to reveal the underlying fire. I tried that here as well. I couldn't really get that classic fireball look that some other houdini pyro users were able to get. Any tips there? I have a smoke density of 40, with the density field being modified by noise. My noise acts on density range 0.0 to 0.6 with a 1.0 to 0.0 distribution curve, and it "eats away" at the density because my output range is -3 to 1. This noise only exists in density field. Related to this--since I am eating away at the density of the smoke, how can I get nice noise on the surface? I would think that I would have to add to the density rather than eat away. This one throws me for a loop--- if I modify smoke density by a default field, there is no change (which I expect). If I modify density by a noise field, the noise acts on the density accordingly (which I expect). If I modify the noise field by the a default field, then modify the smoke density by the noise field, all of a sudden it looks different than just being modified by the noise field. The default field doesn't do anything, so I am confused about that. I am guessing the stretching on the bottom of the explosion is not fixable. The smoke is being pushed along that lower boundary and I think weird things are happening. Is the only fix for this to not let the smoke hit a boundary like that? My rest leapfrogging is every 50 frames (so I am pretty sure that means a handoff every 25 frames). I don't think it is a rest thing becuase it would look fine every 25 frames at the handoff point, unless I misunderstand. Lastly, the smoke has a very "steppy" feel to it, like it needs a whole lot of motion blur. I see that houdini only supports geometry blur. I allow motion blur and increase the geo time samples and indeed my render looks different. It seems to expand a little, as compared to disallowing motion blur. It doesn't seem to blur or anything like that. Has anyone had any luck with pyro motion blur? Maybe something in my setup is wrong and it makes the geo blur look bad? Is there a better way? I know it is a lot of questions. I can't post the high res explosion because it is too large. But I can take pictures of my settings or explain my scene a little better. I am hoping some pyro guru can look at my scene and suggest a few things I can try. Thanks for reading. edit: I figured out my problem with the default modifier affecting my renders. There are two slots for modifiers next to density field. I had the first as density, second as noise. Then I left first as density and made second a modifier than was based on noise. I figured out I should set the first to the modifier based on density and leave the second as noise. Then it works as I would expect. I guess the choppiness isn't as bad as I thought. If anyone has tips for motion blur on volumes, how best to render temperature against density to get that classic explosion look, or what that stretching is at the bottom of my sim, I would greatly appreciate any insight! explosion_v12.mov Edited August 16, 2009 by loopyllama Quote Link to comment Share on other sites More sharing options...
xmetallicx Posted August 16, 2009 Share Posted August 16, 2009 Hey there, do you mind sharing your hip file on that explosion? I've just started on the pyro tools and have been trying to get that initial burst and shape for the explosion but i'm not sure how to do that. Thanks! Quote Link to comment Share on other sites More sharing options...
loopyllama Posted August 16, 2009 Author Share Posted August 16, 2009 I can't post my hip file right now but check out Jason's hip file here: (the shaped charges one) for my explosion I have a sphere that has the lower half with radial velocities scaled way up. If I can clean up my hip file I will post it. this link should get you going though... Quote Link to comment Share on other sites More sharing options...
xmetallicx Posted August 16, 2009 Share Posted August 16, 2009 (edited) Ah thanks for the reply, i am actually using that point velocities for my motion, maybe i didn't scale mine big enough...either that i'm probably keying the wrong parameters in the pyro solver, will keep trying but thanks again for your help! Well i will look forward to your hip file if you ever do post it Cheers dude! Edited August 16, 2009 by xmetallicx Quote Link to comment Share on other sites More sharing options...
loopyllama Posted August 19, 2009 Author Share Posted August 19, 2009 for the curious: -the stretching was the gas being stretched beyond the sim border. a simple geo matte on the sim border fixes it -the steppiness was because my density was too high -I couldn't get the classic explosion look because I didn't understand the tools at the time (it is all in Mario's video, I just had to watch it 3 times) in the video, the sim is clipping at the top because it is not in frame, and on the side and bottom because of a building and the ground not visible in this test in the image, it is a higher step size so the image is a little fuzzy. it is too much noise in the smoke for my taste, but I wanted to post the image to show the effect explosion_v14.mov 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.