magneto Posted February 4, 2015 Share Posted February 4, 2015 (edited) Hi, If you have a dense particle system, is there a way to upres this so you get a much denser result, as if you had a lot more particles in your simulation. Currently I am saving them to disk and vary the seed with a Wedge ROP and then bring them into the render using Delayed Load Procedural, but I am wondering if this is the proper way and/or if there are better ways to have extremely large particle counts? If there are multiple ways, I would love to know each. Thanks Edited February 4, 2015 by magneto Quote Link to comment Share on other sites More sharing options...
rayman Posted February 4, 2015 Share Posted February 4, 2015 Never tested on particles-to-particles, but it should work http://forums.odforce.net/topic/20333-sand-blowing-over-sand-dunes/page-2 2 Quote Link to comment Share on other sites More sharing options...
ciliath Posted February 4, 2015 Share Posted February 4, 2015 well, u could always use a point replicate in sop 2 Quote Link to comment Share on other sites More sharing options...
magneto Posted February 4, 2015 Author Share Posted February 4, 2015 (edited) Thanks guys, I tried point replicate but the results are not as good since I want them to blend/interpolate using particle velocities, etc. I might be missing some options though. Btw rayman, that sand solver you made is insane Edited February 4, 2015 by magneto Quote Link to comment Share on other sites More sharing options...
pbarua Posted February 4, 2015 Share Posted February 4, 2015 Since POPs are now in DOP land so upres should work. Alternately you can use Point Replicate Procedural SHOP to replicate point at render time. That way you can save memory load. It's just same as Point Replicate SOP but gets run by Mantra at render time. Only drawback is viewport display which you can see using Point Replicate. If you have good machine then you can go even billions of points using Point Replicate Procedural SHOP. 1 Quote Link to comment Share on other sites More sharing options...
magneto Posted February 4, 2015 Author Share Posted February 4, 2015 Thanks, what kind of technique is best to emulate particle advection to particles using Point Replicate Procedural SHOP? If I just add more points within the radius of each point, then it doesn't look very realistic. rayman's method should be a good solution here I think. But if there are other ways to spread more points in the velocity field of other points, I would like to know them. Quote Link to comment Share on other sites More sharing options...
pbarua Posted February 4, 2015 Share Posted February 4, 2015 Go through these: http://vimeo.com/89832209 http://www.sidefx.com/docs/houdini14.0/nodes/shop/vm_geo_ptreplicate http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=28211&highlight=&sid=5adde06add68aeb72b1af1c1f7a95935 https://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=35453&sid=44020071e126a5e25612e40ce7bd68a2 http://forums.odforce.net/topic/18474-add-particles-at-rendertime/ 1 Quote Link to comment Share on other sites More sharing options...
3iart Posted February 6, 2015 Share Posted February 6, 2015 But if there are other ways to spread more points in the velocity field of other points, I would like to know them. I think that's your answer right there, couldn't you just create a low rez velocity volume from your original point cloud, then add your uprezed points and advect the points in a volume sample vop? 1 Quote Link to comment Share on other sites More sharing options...
magneto Posted February 6, 2015 Author Share Posted February 6, 2015 I can try that though I am not sure if a low res volume can capture the movements of the particles accurately as move very chaotic, not jittery. Quote Link to comment Share on other sites More sharing options...
sebkaine Posted February 22, 2016 Share Posted February 22, 2016 (edited) Ryan i would be curious to have your conclusion on the subject ? I have to replicate tons of particle like in krakatoa ... Basically we have : - SOP point replicate - SHOP point replicate - custom tools i am not that impress by the default tool , but maybe i'm doing things wrong ? - SOP is slow and not impressive - SHOP is not exportable for external engine like arnold or clarisse for the moment i'm more on trying to find my own vop/vex tools do achieve this ... something with a mix of : - addpoint vex command + pop velocity + non divergent curl noise + point proximity what do you think ? Cheers E Edited February 22, 2016 by sebkaine Quote Link to comment Share on other sites More sharing options...
fuat Posted February 22, 2016 Share Posted February 22, 2016 I have to replicate tons of particle like in krakatoa ... another option is the Wedge ROP. i used it recently for a krakatoa-job, simmed "only" 30 mio particles, wedged 10 times with different seeds (takes a few minutes to setup), which made 300 mio particles in the end, rendered with Krakatoa: http://insekt8.de/I/houdini-custom-divergence/ fuat Quote Link to comment Share on other sites More sharing options...
sebkaine Posted February 22, 2016 Share Posted February 22, 2016 Thanks for your help Fuat ! In fact i have omitted this option, and it might be the most intelligent and straightforward as it is what Krakatoa do at the end ... So we have : - SOP point replicate -> Slow not so impressive outpout - SHOP point replicate -> Mantra Only not exportable - Wedge ROP + Various seed sims -> Simple to setup / accurate dynamics - Custom VEX / VOP tools that use the addpoint fction -> might be nice too but harder to do Other things i have forgot ? Any hint on the subject would be useful ! Cheers E Quote Link to comment Share on other sites More sharing options...
bandini Posted February 23, 2016 Share Posted February 23, 2016 (edited) Emmanuel, You could try the gap-filler otl I posted in this thread: http://forums.odforce.net/topic/18111-flip-smorganicsheeter-effect/page-6#entry145719 Some of the methodology/theory behind it is described in this paper: http://magnuswrenninge.com/content/pubs/ProductionVolumeRenderingSystems2011.pdf (Starts at page 157). This isn't a complete version, as described in the pdf, but a good base to start from (and the code isn't too complicated, either). This is done in sops but can easily be done as a point replicate procedural. -Adam Edited February 23, 2016 by bandini 1 Quote Link to comment Share on other sites More sharing options...
sebkaine Posted February 23, 2016 Share Posted February 23, 2016 (edited) Thanks a lot for your help Adam ! This look great , and it's full vex ! Thanks also for the surf-up publication, this the best starting point i could find ! So we have now 4 working methods to do uprez of particles in H 1 -SOP point replicate 2 -SHOP point replicate // I would be curious to know if they are exactly using the same methods under the hood or if one is more advanced ? The SOP point replicate is not good enough imo , but i might be doing things the wrong way ! 3 - ROP wedge to create various seed sims 4- your point replicate tool base on the surf-up paper Do you have any other idea on how to do this , 3 and 4 looks at the moment the best choice ? I would also have think about generating a volume from the low rez POP sims add some noise according to velocity and readvect more pop from this rework volume , that might be too slow or stupid but maybe VDB has some tool to offer with VDB advect + VDB analysis ? any test done in this direction ? Thanks for your lights ! Cheers E Edited February 23, 2016 by sebkaine Quote Link to comment Share on other sites More sharing options...
bandini Posted February 23, 2016 Share Posted February 23, 2016 I believe SOP and SHOP point replicate are the same thing, just one done in geometry context, and the other done at render time. I played a bit with render time point replicate and found it to be a little slow, but able to handle a lot of points. I would say for best results, to go with wedging multiple seeds of the same sim. This is what I have done in the past when I need lots of points. I usually set up 10-12 wedges with a wedge rop and send them off to a render farm, so each machine does 1 sim. Pretty fast and efficient that way. The gap filling method will produce some internal cellular patterns, which could be ok or might look strange. There's a variety of looks it can produce. Velocity sampling... I guess I would skip volumes and just attribute transfer velocity from one sim to a higher resolution emitter point cloud, through point cloud lookups. Not sure you need to convert to a volume. This is similar to smoke upres methodology. Adding some wavelet or curl noise on top would create some additional details. This can work, in a sense, but I think you will end up with some fuzzy looking results. Might be ok, I am not sure what your final goal is. 1 Quote Link to comment Share on other sites More sharing options...
bandini Posted February 23, 2016 Share Posted February 23, 2016 One other thing to think about, as well, is to optimize the pscale of each particle, so they render out as pixel, based on distance from camera. You may need less particles than you think, this way. 1 Quote Link to comment Share on other sites More sharing options...
sebkaine Posted February 24, 2016 Share Posted February 24, 2016 (edited) Many Thanks for all the info Adam ! I'll go with the wedge ROP , simple , predictable and give accurate outpout. Like you said when you point replicate you sometimes introduce weird stuff. For the pscale things basically you advise me to do the same as the default point particle in Maya. Basically whatever the distance the point will looks to have the same size. So i deduce from this that in H you can't have point that have all the same size like in Maya, so you have to compensate this with a ramp from distance to cam. Thanks again for the tips ! i post the peter quint tuts about the wedge rop here just in case; https://vimeo.com/154723870 https://vimeo.com/154721078 https://vimeo.com/154721076 Edited February 24, 2016 by sebkaine Quote Link to comment Share on other sites More sharing options...
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