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Justin K

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About Justin K

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  • Name
    Justin K
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    NYC
  1. Revolving Pyro Simulation

    Hey! Im trying to get a pyro simulation that slowly rotates around in a circle, with an open center. Best way to imagine this is with a camera that is inside a hollow tornado, surrounded by a circular wall of smoke. I have to make a section of this wall. Then Im hoping I can instance the simulation a few times to get more depth...... Ive had decent success with the vortex force and a static collision object. Vortex force drives a circular motion and then a static obstacle object in the center keeps it hollowed it out. I run this for a bit and then I get a revolving band of smoke. PROGRESS! There are some issues though. The simulation itself is slow (a thousand reasons for this I know there could be). The thing is I have been pretty thorough with keeping the resolutions and voxel grids as large as possible for the test part of the process. I was hoping I could iterate quickly. But its not happening. I have a just a few spherical emission points arrayed in a circle (only 11,000 voxels), and then I feed this into a pyro sim with a pretty agreeable division count (result is around 150,000 voxels). Its still taking a long time to sim. I udnerstand this is hard to debug without a scene file, but out of curiosity has anybody found an efficient alternative way to do this? I originally created a radial velocity field in hopes of driving the sim, but the control was nowhere near as good as the vortex force. Any tips example files or suggestions would be appreciated! Thank you!!!!
  2. Trying to recreate a venation algorithm.

    Hey Ballington, Its been awhile since I have worked with this stuff. I have successfully gotten a leaf venation system to work, building off of the efforts of those who have gone before me. It turns out, the most efficient method to get you started with leaf venation is a reuse of the space colonization algorithm showcased here: Now i guess it depends on what your goals are. I wanted to make realistic veins for texturing displacement. Using seeds to randomize the result. This is quite possible. Ive attached some picks that show the system working based off entagma's code. There is a problem though. The algorithm is not intelligent enough to organize the resulting geo in a logical manner. Its a madhouse of prims and points, trust me. Thats where you come in. You need to create a logical system to help with the creation of geometry itself. First, you need a generational pattern. Main stem, first gen, next stem, second gen etc. Ive attached a pick that shows the logic of this process. Once you have a generation setup, you can loop through each generation using connectivity, and create a a width attribute along each 'vein' this will be what drives the size of each vein when you actually add geo. Ive shown some picks of a nice result. You can then literally project this geo onto a heightfield and export a displacement texture. Now its challenging and there are all sorts of loopholes along the way. I wish I could show you the code, but its not soemthing I am allowed to share. All the best mate!
  3. Hey folks, trying to get a heightfield map, exported as an exr, to work as a texture on a grid in solaris. Im trying to get it work with both the viewport first, and then karma second, but I am not having much success. Anybody have any experience with this? Attached the scene file and the exr texture. Thanks!! height_v001.exr heightfield_testing.hiplc
  4. Storage

    Thank you Symek, thunderbolt 3 in conjunction with the ssd g-speed shuttle would be perfect, but it seems like getting it working with an AMD system might be a bit tricky, which is unfortunate. I guess only two motherboards for amd cpus are thunderbolt approved, and they trade the 40 GB network spot on the motherboard for a thunderbolt 3, and so dont have both :(. Might seem trivial, but it makes flexibility more of an issue--if I ever wanted to run things using a network. The usb 3.2 gen 2x2 (usbc type) is the closest equivalent (20Gbs), and is about half as fast as thunderbolt until usb4 comes out, so perhaps that will be good enough.... At any rate, that speed shuttle is beautiful--seems like it would be perfect for storing footage on location, though as you say despite redundancy probably would need to have that stuff saved elsewhere. Now for the network option, can I get away with not using one of those expensive switches if I only plan on directly connecting to one pc?--and then perhaps just being able to look at files here and there on a slower wif based laptop? The actual NAS storage seems somewhat 'reasonable' otherwise-by that I mean around 3k. Reading this article here anyways: https://nascompares.com/2019/10/07/thunderbolt-3-vs-40gbe-nas-in-2019/ It conveniently also showcases thunderbolt, but I am not going intel for this build largely for price reasons....... At any rate appreciate the points though. I might wind up getting a high speed 2 tb ssd to work locally off of, and then get a network nas to just back stuff up to on a daily basis. It wont be live, but at least it will be safe (enough). Im just a bit worried about the 2 tbs. I feel like with iterations you can run out quite quickly :(.
  5. Storage

    Hey folks, I’m building a new workstation, first personal build, and I’m struggling a bit with understanding the best way to set up high speed storage for simulation work. Now in my current pc I use a small high speed ssd (128 gb) for my boot drive, and an additional mirrored raid for storage. That raid drive does not have nearly the read write capabilities of the ssd drive though, which in the end impacts performance. I’m upgrading and I want to find the most optimized way to work with large amounts (> 1 tb) of data, in a way that doesn’t require constantly transferring files and folder structures. So this is what I’m struggling to grasp. I’ve been told to get the lowest latency fastest read write combo for the boot drive. So I’m getting a Octane 905P (storage up for debate) for my boot drive coupled with a threadripper processor. That all makes sense. That in and of itself can have up to 1 tb of storage, which is a lot. However, does it really make sense to work off of that drive? I frankly don’t think so. Though it would fit a lot of simulations, if I had a 14 shot sequence, with iterations, then it would probably make sense to have a live storage capacity of let’s say 10 Tbs worth of storage to hold the data....... But then your speed is compromised right? If my Houdini files are housed in the same locale as my sim and render data, then I’m at the mercy of that drive’s read and write speeds regardless of how fast my boot drive is right? I guess that’s the key here. How do I pair a high profile boot drive with a blazing fast storage solution. Ive done research into setting up nvme raids in pcie4 slots, which could get me say 4 tbs of storage, but anything higher than that is seagate nas level storage with I don’t know much about and doesn’t seem to be the fastest way to work live.... I don’t have an insane budget, around 6k and also know nothing about setting up something like a home nas. But usually that seems to be for long term storage not ‘live’ storage, though I have heard about fiber optic cable connections with (10 gb/s) transfer rates- I’m all ears for insight on that. Well.....trying not to be ranty here, but I hope this all makes sense. Absent a render farm, the multi core threadripper (3970 or 3990) with an optane boot drive seems to be the fastest home combo for Houdini sim and rendering, now I just need to understand this elephant in the room, STORAGE. thanks in advance for any insight!!!
  6. Hey! Can anyone explain the difference between these two approaches when applying velocity fields to a pyro sim? Example 1: sop vector field piped into a field force after the pyro solver itself Example 2: Same sop vector field imported into dops using a source volume dop. Volume is called force. This volume is called in a gas advect dop --piped into the advect input of the pyro solver itself. Im having issues with method 2. Overall I am trying to make a pyro sim narrower--and am using a custom velocity vector field to try and force the gas to stay more compressed, but I cant get convincing interaction with the divergence stage of the sim. I had been trying the gas advect for a while, but now Im trying the example 1 approach. I was curious as to whether or not the field force would work better because it is actually operating independent of the pyro solver with its nondivergent stage . Thanks!
  7. How can I set up my preferences so that simulations are disabled and update mode is manual whenever I open a houdini file? Thx!
  8. Hey--im reposting this here -- this video was extremely helpful in resolving my problem. Thank you Andrew!!!
  9. Hey, besides gas curve or gas blur (the microsolver being used for the viscosity parameter), is there a way to keep a smoke sim column tightly compressed for a longer period than usual? Basically I want to keep a smoke plume compact for a long period of time (tumultuous but not dissipating), even as it is being pushed by a wind force. Im struggling to achieve this affect without the column being blown apart. Viscosity keeps the column together, but also makes the plume move like a fluid . Id like to keep the column compressed but also have a lot of turbulence within the column. The result is achievable easily enough without wind--with wind it seems difficult.... Ive attached flipbook of what i have at the momvent--the column shape would be great if the smoke movement wasnt so contrived looking Thanks sim_test.mp4
  10. Hey, Ive been tasked with recreating smoke plooms for a composite. Im new to pyro, but Im slowly familiarizing myself with the pyro solver for the task at hand--apllied houdini dynamics has been enormously helpful for this. The best reference for what we are attempting to achieve large scale structure wise is this https://www.shutterstock.com/video/clip-1006794988-chimneys-power-plant-sunset-air-pollution-concept Secondary example would be this: https://www.shutterstock.com/video/clip-1022524201-hamilton-ontario-canada-january-2019-factory-steel Two issues I am really struggling with are: 1) keeping the structure of the plooms together over time (say 800 frames)--while still moving in the specified direction. Im referring to this as the large scale shape. 2) keep high levels of disturbance and movement within the plume structures even when they get far away from their original vel source. Small scale detail retention I have noticed that generally speaking, over time in the pyro simulation, the sim inevitably starts to disperse and smooth out. I know there could many reasons for this:. A few things that could be affecting this as far as I would know: 1) temperature diffusion (this could cause smearing)--consequently to counteract this, I have this very low. 2) turbulence issues: Its needed as far as I can tell to give the plumes variation in structure. However turbulence applied globally over a long enough duration with secondary wind force will slowly spread the density apart in all directions throughout the volume. This makes sense but is perhaps also a problem. We need turbulence, but the turbulence cant blow apart the structure with time in this case. 3) rules of incompressibility in pyro sims? --Ive listened to some explanations where this rule is actually somewhat problematic when it comes to something like a smoke plume or an explosion, where the volume of the sim should actually be increasing over time. I currently am NOT using combustion though....perhaps I should be? Perhaps a useful question to ask is: When smoke leaves an exhaust pipe is it combusting? Or simply cooling off very quickly when it interacts with air? --science help! (thx!)) 4) Incorrect temperature change?--right now I have it losing temperature very quickly--which I believe is what happens in nature with smoke plumes, but Im not sure. Im hoping this gives the smoke a heaviness and keeps it from rising--However, the smoke column still needs to be very active within the confines of its own shape....... 5) Incorrect time steps? Right now I have the timescale of the sim set quite low (.2) --in hopes of keeping the sim from emitting and blowing apart too quickly--again, not sure though At any rate, any tips on this stuff would be REALLY appreciated. I understand on a basic level what the differnet microsolvers are doing, difference between importing volume fields to affect things, as opposed to using microsolvers, and alternative effectors like wind force, so any tips would be helpful. OK, so, the current state of my terrible sim lol: I have tried a variety of different things to achieve the desired look. One of the first things I tried was driving the plumes along a curve. However, I could not get the sweet spot as it were with this method-- the sweet spot being: the plume followed the curve structure wise, but did not stretch out and loose shape as it followed the curve. Basically the plume wiould start to smear with the curve if the attraction was too high, or, conversely, if the curve attraction strength was not strong enough, the velocity pushing it along the curve would not be enough to keep the plume from rising into the atmosphere with temperature. I did try for a while to get the velocity force along the curve and the temperature to play nicely together, but was unsuccessful overall in keeping the plumes from looking like they were being pulled rather than pushed in a direction. I gave up on this art directable shape idea, and instead went with a costume wind volume I built in sops. This is currently pushing the volume in the wind directionx, and there is some slight oscillation in the y values and the amplitude to give it some visual interest. A turbulent noise is running with a time offset as well. THis velocity volume, I should point out, is NOT being applied globally to the voxels, Im using the density as a mask in hoping of keeping the thing from falling apart--and yet it still is .. One side noteL As a side note: the intial shape of a pyro sim is different look wise from the look in say 200 frames, where the emission and the general look have become more consistent. In other words, there is an initial blast structure and then what comes afterwards. In my case, I dont want the initial blast of plumes, but instead want what the sim looks like when it has achieved some sort of balance. Is there a way to avoid having to look at this rev up time every time I sim? I was thinking of saving checkpoints, say to frame 200, then simming from that checkpoint. I would sett keyframes for everything I was tweaking at frame 200, and then at 210 dialing in new values and see what my sim looks like as the changes evolve? Is that a common thing.? Any other questions you have about my set up feel free to ask! Ive provided a scene file--SCENE IMAGE shows the network that is being used for this --everything in the purple background. Ive attached a flipbook still for whatever reason as well. Hope this is enough enough here all, Any tips or pointers would be greatly appreciated. Thank you! smoke_plooms_v003.hiplc Still_Ref.zip
  11. 3d Volume from Image?

    Just as an update on this--we have killed the project. The image we were given did not relay itself well to the concept itself-- it was an image of a man comped against a sky to begin with. If we were to do this in the future, we would generate some 3d geometry to help the cause. Szymon your heads up on the depth matte from image software is a really great thing to keep in mind though. Thanks for the tips both of you. Best, JK
  12. 3d Volume from Image?

    Thank you as well Szymon, Taking a look at your file as well. Unfortunately we do not have depth from the image. As you questioned, that is the challenge here. And I agree with you completely, having some sort of geo should help. Im gonna see what happens applying Konstantin's code to a premade 3d cloud volume and see what i get. What we might try--is to generate some real proxy geo of the image, project the image onto the geo as a texture, convert that into a volume, and drive both the color and the density of the volume with the color from the point or vertex level. Maybe? Lol Thank you both. Ill post here again with a file if I have any success. Cheers, JK
  13. 3d Volume from Image?

    Thank you Konstantin,! Implementing this code this morning.
  14. Hello, Is it possible to generate a 3d volume with depth from an incoming image? Request is to convert a figure from an image into a cloud like structure, and Im trying to figure out an intuitive way to do this. Currently Ive just manged to take an image mapped to the uv coordinates of a piece, scatter points based on the color, and then create a volume from that, but that is all i have so for. My thought was to perhaps deform the geo based on the luminance values of the image so as to give it more depth, but overall Im not really sure how to approach this. Ive attached a pic and the current scene file. Any tips would be appreciated. Thank you! image2cloud_testing.hiplc
  15. Well....it works!!!! you dont even need to go into the subnet--just bind your parameter to the outputs you want--you can then rename the channels if you want the export names to be different.
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