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Justin K

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About Justin K

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    Justin K
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  1. 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!
  2. How can I set up my preferences so that simulations are disabled and update mode is manual whenever I open a houdini file? Thx!
  3. Hey--im reposting this here -- this video was extremely helpful in resolving my problem. Thank you Andrew!!!
  4. 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
  5. 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
  6. 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
  7. 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
  8. 3d Volume from Image?

    Thank you Konstantin,! Implementing this code this morning.
  9. 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
  10. 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.
  11. Hey all, the bake texture rop provides you with a convenient way of sending out point colors to a texture map which is really helpful. I sent out a costume curvature mask in this way created from the game dev curvature sop. All you need to do to get the curvature values out into a map is 1) Apply a principled shader to the desired geo. 2) Have a light 3) Set the shader to use point color. 4) In the bake texture rop, check the Surface unlit base color (basecolor) That was all it took --some thanks for some online help for this by the way. My question is, what would be the smartest way to kick out multiple masks from the bake texture rop? Say I wanted to send out 5 or 6 different curvature maps as flat color information, can I hijack one shader to do this? Im pretty confident I can but Im not sure of the workflow. My thought was I build up a set of attributes corresponding to my masks: say v@curve_mask_one v@curve_mask_two etc etc and then try to just hijack some of the preexisting inputs with this attribute --say the metallic, the transcolor, etc etc. Looking inside the shader network i can see how the various parts --basecolor, metallic are set up in a very similar fashion. I showed a pick of the the surface and the metallic to show how similar they are (pics 1 and 2). You can see they both have an option for using point color. If you then dive inside there is this bind labeled Cd (pick 3)--is this Cd attribute bind what is calling the point color to begin with? If so, I figured I could just replaced the Name: Cd with say curve_mask_one and the bake texture would behave appropriately? Maybe...... there is nothing inside these subnets that actually applies to how the shader is building the differences between the metallic and transcolor maps though, thats my fear here. I am trying this out now, but also sending this in hopes of getting any suggestions so I can avoid any rabbit holes here. Thanks in advance for any suggestions!
  12. Hello! Im trying to utilize the attr token provided in arnold. Its supposed to allow you to use user defined attributes to change things in the shader --in this case allowing me apply different texture sets to primitive groups with the same uvs. In this case there are six pieces of geometry, with an id attribute and a string attribute set to the file name they should be grabbing for the texture. The syntax is supposed to be something like this: https://docs.arnoldrenderer.com/pages/viewpage.action?pageId=55711930 (see pic as well) So Im pointing to the folder and then writing in the attr as is suggested, but Im not getting any results. Anyone know what I might be doing wrong? They are exr files--in one texture folder. When I point directly to the file location the file reads- so i dont think it is the file--i think I am just not typing something correctly. Yeesh. Thanks!
  13. Hey all, as I said yesterday I have everything working (well from a technical perspective lol) for my maps thanks to all your help. I am doing look dev now, and the feedback is well....a bit slow. It's not like I'm being brutal with settings either--I just have one flower I'm look-deving. Im doing my due diligence and am gonna try to use mantra for this--however--as an example- a scene with just a 1k environment light+one area light, one flower without material overrides, 1 displacement map for theflower, and two shaders (one for a sphere sitting between the petals and the area light, and one for the petal) is taking 10 minutes to render with standard mantra settings and a 1280x720 camera ???? Displacement effect scale is at .002- the geo is low res, transparency is set to .1152 --slightly translucent-- and the subsurface is set fully to 1. Im not sure this is gonna be all that efficient, unless mantras optimization starts to showcase itself when the amount of geometry significantly increases...... My question is would it be worth switching over to Arnold for this. Arnold has some really nice translucency capabilities-- and I have some decent experience with it for a paper project I did a while big. However, the big question then becomes: can I use these material override setups inside a third party renderer? or is this just a mantra specific technique? Thank you!
  14. Thank you everyone for your help! I have it working now! If anyone would like the file at some point just flag me and ill send out a simplified version All the best Justin
  15. Saw this while writing the other response--thank you! Looking at your file now
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