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Activate last won the day on June 11 2017

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About Activate

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  • Website URL
    https://www.provos.org/

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  • Name
    Niels Provos
  • Location
    Mountain View, CA

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  1. Would anyone here mind posting an example file that produces Custom AOVs for Redshift 2.6.38 and Houdini 17.5? Neither default shader nor Store Color to AOV or anything else is working for me. Sample file is attached. broken_aovs.hiplc
  2. Tileable Noise

    That makes a lot of sense. Here is the same thing but converting one dimension to polar coordinates. It makes for a much better result. The tiled result looks nicer as well. noise_tile_v2.hiplc
  3. Tileable Noise

    @rohandalvi was asking on Twitter about tiling noise in Houdini. It seemed like this should be easy to do. That should have been a warning sign. Doing this right is much harder but here is a super quick blur based noise tiler: Since blurring is feature agnostic, it does not make for the best tiles but may be good enough for some cases. Hip file attached. noise_tile.hiplc
  4. Help with Leaves on a Tree

    Thanks for the feedback. The trees are not based on L-systems. The growing algorithm is based on papers published by Runions and Prusinkiewicz. The orientation and position of the leaves is based on phyllotaxis which is really hard to see in the image. Here is a close up: It's possible that I am anchoring too much on where the tree simulation places the leaves and instead should just go with some scatter based approach of placing the leaves. Part of determining in which direction the buds will grow into branches is based on space colonization and a volume that circumscribes the outer extend of the branches. The volume gets filled with marker points and uses space colonization to select the buds nearest to each marker. Houdini is still pretty much a learning experience for me. Graphics is not really part of my background but it's a good creative outlet. Thank you.
  5. Help with Leaves on a Tree

    Still trying to figure out leaves; some progress.
  6. Using python for convert file sequence path

    Do you have examples where this does not work? The regular expression replaces occurrences of $F4, etc with *. The * is a wildcard for globbing for matching files in the filesystem. expandString does all the Houdini magic to turn the expression into a complete path. If your path just contains file.$F.png, the regular expression above will not match and then expandString will substitute the frame number, i.e. you only get the first frame. Try to use r'\$F\d?' instead.
  7. Help with Leaves on a Tree

    I have not made much progress on the leaves but started with shading the trees. Not really what I asked about originally but here is the current look - most of this will not be visible once the leaves are attached as well. The tree bark is from a photo processed with Bitmap2Material to get the normal and displacement maps. The main challenge here was manipulating the UVs from Polywire, e.g. scaling the uv.y dimension by the length of the branches. If anyone here has feedback, I would appreciate it.
  8. Help with Leaves on a Tree

    Thank you. That is providing some good food for thought. I had previously only attached leaves where buds had not grown into branches. I like your attribute wrangle to bias the orientation of the leaves. I will experiment some more
  9. Help with Leaves on a Tree

    Hi everyone, I am wondering if somebody here would be gracious enough to help me with putting leaves on a tree. Here is the context, I grew myself some trees by implementing some standard algorithms: and am now looking to put some leaves on the trees. I modeled a super simple leaf and instanced it: I don't like the look of the leaves and I am not happy with their orientation or really the overall appearance of this. The process of growing trees gives me a lot of attributes to play with, e.g. the direction of the buds, the direction of tropism, the growth direction, the steps in the iteration, the degree of the branch, how much light a bud sees, etc. If somebody here with experience would be willing to put me on the right path I would appreciate it. Hip + geo attached. Thank you, Niels. tree_example.zip
  10. I am not sure if anyone has run into this but I thought I would quickly share this. I am using a pop sim to source vellum grain. The pop uses 2 sub-steps and for various reasons, particles get sourced on non-integer frames, e.g. 6.5. I noticed that when I am using vellum, the grains never appeared even though the vellum sim was set to 2 sub-steps as well. To make it work I had to change the time step to 0.5 in the vellum source sop solver enable solver node. Here is a screenshot: Someone else might find this useful at some point, I hope, or perhaps I am just doing something totally silly :-)
  11. Houdini 17 crashing constantly

    Houdini should tell you where it saves the crash logs. For me, they show up in C:/Users/<username>/AppData/Local/Temp/houdini_temp/. If you are lucky you can also find a saved version of your HIP file in there.
  12. Smoke is "killing" me

    Hmm. I was hoping that someone could share some sage wisdom but perhaps my questions are too naive :-)
  13. Smoke is "killing" me

    While the subject may have been true in the Bay Area last month, the subject is much more about the vexation of getting smoke right. I had found a little bit of time to go through Steven Knipping's Rigids II video and decided to add some debris and smoke. To source the debris and smoke, I processed the constraint breaks. For the smoke source, I made a tiny pop sim with noise and some velocity filtering. The smoke for the explosion has pretty high velocities, e.g. around 30 units/s. Initially, the smoke was basically just smooth mushrooms. I then introduced a high value disturbance against the velocity field in the low density areas. This broke up the smoke but I never was able to get it right. Here is where I ended after I had decided I had spent too much time; see video below - ignore obnoxious sound track :-) Would anyone here be willing to point me in a direction on how to improve this? I ran a bunch of wedges against lower resolution simulations. The overall smoke container ended up being really large, so sim-ing and rendering low resolution wedges took a few hours of turn around. Hip file attached for anyone who wants to take a look. Thank you, Niels. rigids2_v7.hiplc
  14. BTW, does anyone know how to texture a setup such as this one where the same pieces (from the wall) are re-used to create the whole building? Perhaps that is not a very common set up.
  15. This works great. Thank you! Starting with "fresh" points really did the trick :-)
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