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Josami

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About Josami

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    Jos
  1. Hi! A couple of months ago I started a topic about a FLIP simulation crashing after reaching some frames. I decided to open a new topic because after a lot of research I finally found what the problem was and it had nothing to do with my GPU and had not experimented a Houdini crash in the last two or three weeks. First of all I want to tell you that the problem got worse than what I wrote in my last topic. In the beginning the problem had to do with FLIP sim crashing at certain frames. It could be 1/3 into the simulation or, more commonly 2/3 into. I only could do low res simulation. That was weird and because of that began to think that it was a hardware limitation problem. Then, after learning more about checkpoint files and kind of giving up on solving the problem, I decided to try some render. Again I wasn't able to go over 50% with medium quality settings. So I took my PC to a technician and start working with him. He did some hardware cleanup, replaced my GPU thermal paste and chage it to a different slot, and clean my ram sticks and change their order. After those adjustments I finally could finish my sims and even render! I did several simulation tests and run a render that went on for more than eight hours straight, which was great news. However, after I picked my PC and plug it in in my house, the problems came back. I started to think it had to do with my UPS or my socket not delivering enough power, so I tried to connect it on different rooms in my house. One thing to notice is that, at least, at this point Houdini was returning me an actual error code, which was: Command Exit Code: -1073741819. It is a windows error. I found some topics in this forum and sidefx's, but unfortunately none of them included any solution. Windows forums talked about some incompatibility issue caused by audio drivers. Maybe because constant crashes and the core problem being stressed, my PC started outisde of houdini and went through many blue screens with many different errors. New things I tried: followed the instructions about audio settings, used directx in order to look for any incompatible driver (NoMachine Audio one popped up, so I uninstalled it after reading in some site that it was cpu expensive), tried both sim and render in houdini and in the background (which was a lot more unstable). So I decided to open my case and test every ram slot and run test stress. After several hours I discovered the problem was, indeed, my ram. My configuration had 128gb ram, however, I first bought a 4x16gb kit and then add another 4x16gb same model, same frequency, same everything, but different kit. Despite of being the exact everything, those kits were not tested together and so run through incompatibility issues when working together. If I put my old kit, everything went fine; If I put my new kit, everything went fine; but as soon as I combine them, the problem arose. So, just to sum it up: my solution to several houdini crashes and windows crashes, and error Command Exit Code: -1073741819 was ram incompatibility. I should have bought a single 4x32gb kit instead of 2 4x16gb of the same model and frequency.
  2. GTX 1080 may be crashing sims?

    Great! Thank you very much for your observations. So basically, it was indeed pushing my workstation to some point, although it was still kind of manageable. Those are great news! I will resim taking that into account for sure. Thank you very much again!
  3. GTX 1080 may be crashing sims?

    Hi! I've been trying to push my computer in order to find out its limits. I have a *Threadripper 1950x *128gm ram at 2400 (I know I could go for a better choice, but I wasn't aware at the momment) Right now *GTX 1080 *Windows 10 *CPU max temperature 67C // GPU temperature max registered is 71C according to HWMonitor, but it usually is between 45 and 71. I'm running a FLIP simulation with .075 particle separation and a box container of 75x75x125. It is an 89 frames long simple animation of a water emision colliding with two rocks and a terrain. Its final particle number is 10.5m and the surface and velocity volumes are along 8m. While I have rendered the total number of frames succesfully one time, it did crash a lot before. Frame number varies, but it could be between 30-70 frames. Whenever this happened, my task manager registered a GPU peak from 0%-3% to 100%. It doesn't fills the ram. At crashing time it could be using something between 28-60gb of ram. At this point I've already tried 1) updating my gpu drivers, which indeed was allowed the simulation to finish, 2) disabling opencl in the flip solver also keeping it on but with CPU calculations instead of GPU. This made the simulation slower and I still got the random GPU peak. 3) trying to disable GPU right from the houdini.env, which was a bad idea because my CPU temperature got really high. Something interesting is that at some point of like two frames per minute, my CPU goes from registering peaks to a constant 100%. When this happens, time spent in simulating a frame can go up to ten minutes, although after it finishes, the next two or three could take a couple of minutes. The one after those will again last ten or more minutes, twenty minutes for the last frames. Ram could be around 60gb at this point. Maybe I've already met my PC limitation, which is fine if that's the case. However, something feels weird and maybe someone knows what is going on. Thank you very much for reading my message.
  4. create interactive Fog

    Hello angeldev, How are you trying to approach this? You could use collision inside a smoke solver.
  5. Problems with dandelion wire sim

    Ok, I think I found the answer to all the questions. 1.- The forces are being applied at all time, but the speed of the movement makes it difficult to notice. I slowed down the simulation using a Retime node and a Polywire, and the noise is there. A SOP alternative to intensify the vibration could be adding more noise over the rest position of the probes, but I think that won’t be needed. 2.- This one has to do with the force and the frame when the objects are released. In frame number 0 of the “dopnet4”, all the seeds have a pintoanimation value of 1. However, in the next frame, where the seeds are modified by the forces, that value has already become 0. I think the starting frame of the sim is used to feed the solver, so it makes sense to me that the next frame is some kind of stabilized version of frame zero, that is now being affected by the forces. That being said, if you want to keep the modified shape of the seeds you also have to keep the “Solve on Creation Frame” box on the Wire object checked. Otherwise, they will jump back to their initial state, despite of the threshold being reached. 3.- You can animate forces if you change the Default Operation from Set Initial to Set Always. There’s more information in the next link: http://www.sidefx.com/docs/houdini/dyno/top10_medium.html#set-initial-vs-set-always 4.- As I said, I think the starting frame is used to load the object and forces. The noise in my example is due to “noise wind”. Once the sim really begins, everything behaves as it should.
  6. Problems with dandelion wire sim

    Hi! Hope everyone's doing great. I've been working on a dandelion scene, but I have some questions about the simulation itself. Hopefully, someone could help me figuring this out. My setup feds some procedurally generated seeds into a wire simulation. The attributes klinear and kangular are already set in SOPs. Inside DOPs, several forces nodes try to replicate the behavior of the wind. To release the seeds, a Sop Solver compares how much force are receiving the constraints, with a threshold. My questions are: 1.- While the seed is still attached, you can see every prob vibrating because of the “noise wind” node, but once it is released, the forces seem to act over it as a whole. It still moves around, but freezes in its last position. Do you know how I can get all my forces affecting the seed all the time? 2.- Well, the seeds are flying in the same position. Ok, they are moving fast and still rotating so it is not that noticeable. The problem is the last position is different depending on the amount of force received or the time when the seed is freed — I don’t know which, but I think is the first one. That’s kind of obvious, but let me explain. In “dopnet4”, seeds are released at the very beginning. I used two time shift nodes to show how the position of an arbitrary selected seed is affected by the forces, but jumps back to its original state after being released. However, in “dopnet5”, where the seeds are released at the end of the sim, that selected seed behaves as it should and both positions are the same. Do you know why is this happening? 3.- Can you animate forces inside of DOPs? Right now I’m using a vector field to prevent the wind nodes from reaching their goal position. That way the objects keep moving. Maybe there’s a better solution I’m not seeing at. 4.- My simulation starts at frame 0, before my scene begins. That’s because the start frame of all the wire sims I did was weirdly shaped. Maybe the solver needs an initial frame in order to properly load the object, but I was wondering if that’s the reason, or if there’s a proper way of solving it — assuming it is an issue. The “frame_0” nodes show what I’m talking about. Here is the folder with the sim nodes and the baked geometry. It would be amazing if some of you know the anwers. Thank you very much! DANDELION_TEST.rar
  7. Light data to generate geometry

    Thank you very much for your answer konstantin! It was really helpful. I’m thinking of using that shadow as a vector source to modify particles emitted from the character’s body. However, the shadows I'm trying to use are the ones cast over the character's body — didn't explain myself. Based on your sample file I came across the idea of using an external geometry point as a fake light object, using its position to calculate the dot product. Just have to set a normal in the same direction the spotlight is pointing, and reference its position. It's a pretty basic and common setup, but maybe someone finds it useful. FAKE_LIGHT.hiplc
  8. Hello! I've been trying to get light data in some attribute or texture in order to use the shadows to generate geometry. Until now, the best approach has been baking the light as a texture and loading it using Attribute from Map. However, the baked texture works only if the character is static. What would be the best approach to cache or cast lighting data in order to procedurally generate geometry? A shader, maybe? Thank you in advance.
  9. Music Visualisation

    I found your experiments both beautiful and inspiring. Thank you for sharing your website :).
  10. Hello to everyone! I'm fairly new to Houdini and to vfx at all and been struggling trying to do this by trial and error and searching in forums. Even though I have learned a lot by doing that, I think it's better to ask for someones help. I want to create some dust clouds (like a small dust storm) for a shot. Because the area that I'm trying to fill is big and my resources are limited, I thought it would be a good choice trying to achieve the effect using SOPs instead of a smoke simulation in DOPs. The setup related to this part of the effect is basically some boxes each modified by a Volume VOP to add some noise and animation by frame. I read that Billowy Smoke Shader can help you to get a more fluffy look at rendering. My first frame was great, but the next weren't as good because of the noise. The shader is supposed to use the rest field of your simulation to position it, but I'm in SOPs. Another user asked for something like this in the forum: He says: "just create a vector rest volume in the beginning that has the world coordinate of each voxel as its value. Be careful to do all the same advection operations on your rest volume as you do on your density volume". But I think a main difference is that they are working with shaped geometry and my whole dust storm is, well... a box. Until now my tests have been: 1.- Expose rest attribute with a wrangler before my volume vop and create a surface attribute named rest. 2.- Create it after the volume vop. 3.- Create the noisy volume, then convert it back to polygons, add a rest field and then again convert it to fog. And nothing worked. My questions are: 1.- Is there are way to use a rest field from SOP to shape noise in the billowy shader? If yes, what is it and how do you work it. 2-. Or would it be better to create a noisy volume, convert back to geometry, add pyoclastic noise and convert it back to volume? Thank you in advance. I would really appreciate your comments.
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