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About celd

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  1. render length with passes

    Thanks, I was hoping for this kind of solution, you saved us a lot of time!
  2. Hi, I am rendering pyro with 2 extra image planes, combined lighting "all" with light exports, which gives me 3 passes - the smoke lit by 3 individual lights (direct, enviromental and volume light) and combined emission "all_emission" which gives me just the flames. Now all of this is very useful in compositing process, however it also increases render time to 8-15 times the length of render time without passes. I would expect there would not be any increase of render time since it already is a part of the "beauty" render. Is there any way to get around this? Thanks
  3. signed distance field

    use volume gradient for a direction towards the surface and volume sample for a distance to the surface, then add the vector to the points position - use point vop
  4. Right angle box sweep

    Cant you simply use polywire?
  5. houdini vector blur.

    you need to go to Render/Sampling tab on the object you are rendering and tick Geometry Velocity Blur on, and on the mantra node in Rendering tab tick Allow Motion Blur on you will then have motion blur in the direction of velocity vector v in your render
  6. Two Pyro smoke questions

    I will try to answer this with various levels of knowledge I have about your questions: Pump preset introduces velocity into the simulation, you should always look into "SOP to DOP binding" tab, that's where you can see what is actually going on. As you can see in your hip file, it is trying to use a field called "pumpvel" and add it into simulations "vel" field. There is a second field, scalar field, called "pump", which is being added into "pump" field, I believe this scalar field does not actually do anything, however in Masks tab you can see its being used to mask out the vel field, so that the vel field gets multiplied by the pump field, effectively masking it. You can see how these fields are created on the SOP level. The pressure field is the one that you cannot visualize in the smoke object. It is an internal field that pushes against the velocity to make the simulation divergence free. Pressure solve is one of the steps of calculating the solver equation. Now the expand preset does indeed do what you originally wanted to do, that is, add divergence. I admit I am not entirely sure how it fits into the whole picture, but in the end it is not too important to know more than that it introduces divergence into the sim to make it expand. Hope this helps and if anyone wants to fill in the blanks - please do.
  7. Two Pyro smoke questions

    the combustion model's "gas released" parameter introduces divergence into the simulation, you can see it when you look at the field visualisation source it into the simulation just like any other field, as Alexander mentioned
  8. some ways to solve this would be either gluing the larger pieces together in the simulation, or using "active" attribute to not sim them at all it is not exactly what you want to do, but it does the trick
  9. Orientating stairs along curve

    you can use polyframe sop to calculate tangent and output it as N in point sop you can remove the y component of N so the stairs remain level you may also want to create "up" vector pointing up if the orientation isnt behaving correctly
  10. if you are trying to accumulate a value, it could be a good idea to use sop solver instead
  11. FLIP takes long Simulation time

    I believe that to disable caching flip sim into memory, you need to leave DOP caching on and disable Allow Caching on the flip object
  12. by zeroing out I mean literally setting its translate and rotation values to zero, also you connected the fetch/blend/camera the other way arround the idea is that fetch node gets the transform values from your imported camera and blend node filters out its scale, then you parent your copied camera which only follows along, reason why you copy it is simply so it has all the camera settings as your imported one also you dont want your fetch to be connected into the null you scale your imported camera with
  13. you can scale your imported camera by plugging it into a null and scaling the null, you then duplicate the camera, drop fetch and blend nodes and connect it like this: duplicated camera->blend->fetch uncheck SX SY SZ on the blend node, check "use parent transform of fetched object" and zero out all transforms on duplicated camera this way you get translations and rotations of your scaled camera only and wont have render issues due to scaling
  14. Collision field deleting the density field

    in my experience this is often due to "collisionvel" field not being properly set up. this can cause problems especially if the collision object is moving quickly through the smoke volume. it will not transfer its velocities to the smoke vel field and will simply eat the smoke away
  15. Nor am I suggesting you use Maya, having said that, I have not tried rigging in Houdini, but I assume the process would be similar and even easier to automate. From what I can see, the rig is doing what its supposed to, but the deformation is simply too extreme. if you looked at your own arm doing that kind of a motion, it would be twisting almost all the way to the elbow, anything short of that will simply not look good with this kind of polygon density.