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mzo

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About mzo

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  • Name
    Maurizio Zappettini
  1. Flip sim driven by 2D animation

    Thanks for this. Yes, I can see the velocity is now correct in terms of moving in the sim as in the animation. I'm trying to understand what I was doing wrong. Was there a specific step that was preventing it from working?
  2. Flip sim driven by 2D animation

    Thanks, I tried all of those things already but had no luck so far. Here is the hip file. Please take a look when you have a minute. Thanks Anim1.hiplc
  3. Flip sim driven by 2D animation

    That's great, thanks. I had a quick look already, and it seems very useful. Later today, I will follow it step by step to learn better. In the meantime, I have a quick question about the method you suggested yesterday. I put it together in one sim. I used volume rasterize before attribute transfer to get the velocity from the flat volume slice (originating from volume optical flow) and copied it into a 3D box filled with points representing my 2d image. It seems to work as the velocity vectors match the character, including its thickness. For the rest of the attributes (viscosity and density), I assigned them manually to the points depending on their color (I have only two colors). However, once I dive into DOP and start the sim, I disable the gravity, so I only see the velocity influence, and this changes from outside DOP. The movement inside the sim is different, and also the vectors look different. Why is this happening? Thanks
  4. Flip sim driven by 2D animation

    Thanks, this makes sense. I will try to add the velocity computed from the optical flow to the mixing fluid from image data and see if that works. Regarding adding custom velocities to create the swirling, etc., could you point me to some example HIP file where I can study how that works? I normally do procedural modeling in Houdini, so working with sim and velocities is something I'm a little rusty about.
  5. Hi, I'm kind of stuck with something I'm trying to achieve. If anybody could point me in the right direction, that would be fantastic. I'm trying to combine two techniques in the same shot. I have an image that drives a flip simulation. Image has two colors and each color will become a different fluid that interacts/mixes with the other one. Initially, this image was still and it was easy for me to achieve that with attributesfrommap and mapping Cd to viscosity and density. Now I need the underlying image to be an animation (only the character moves, the rest is still). I got the character animation driving the particles representing its shape using the volume optical flow technique. However, I'm struggling to find a way to merge these two systems together and basically add the character movement to the fluids mixing together generated from image Cd. This is a test project folder, which includes the images to drive the sim. motionFromAnim.zip
  6. Hi, I'm trying to achieve an effect where a creamer gets poured into a coffee cup and the two fluids mix nicely together and smoothly like in the referenced video. I'm attaching my project file. So far I either get it too splashy or too dense where there is no mixing. If anybody could point me in the right direction that would be super appreciated. Thanks! testMilkPour.hiplc
  7. This tip is gold. You can't imagine how many times I got frustrated with this silly but very annoying issue.
  8. UPDATE: it now works - I was caching the VDB in the wrong way. However, I hope they will fix this problem soon and allow us to use SOPimport for volumes to be rendered with Arnold in Solaris. It is very limiting to have to write VDB's every time if one wants to build a procedural system.
  9. Hi, I'm unable to render volumes in Solaris with Arnold. I read that sopImport doesn't work with volumes for Arnold so I exported as VDB and imported in lops with both volume and file nodes. The scene renders fine if I use Karma but if switch to Arnold the VDB won't render at all. I'm attaching a sample scene. Can anybody take a look and let me know what I'm doing wrong. Thanks! testSmoke.hiplc
  10. Hi, I am working on a scene where I have a particle system that forms gradually. There is a barrel in the scene that progressively dissolves and a foam-like substance takes its place before melting down. The barrel animation is driven by a pyro source spread, that in conjunction with an Axiom solver also drives the velocity of the POP simulation. The simulation works fine. However, in rendering (with Arnold) I have a bunch of tiny particles under the intended particles that reflect the light source while flickering and these are not present on every frame. This flicker only appears in the render. I cannot see anything in between the "real" particles and the box object below in the viewport. I am attaching the first 6 frames. Any idea what is causing my issue? Thanks
  11. Universal dynamic car rig

    Hi, did you then figure this out? I'm looking to create an automatic/responsive car rig in Houdini for a project I'm working on but I couldn't find any tutorial about this. Do you have any information on this subject? Thanks
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