Houdini: Boolean Volume Denting

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When I saw this tutorial on Greyscalegorilla, it occurred to me that although I liked the results a lot the process of sculpting and posemorphing would be a bit too unflexible for my needs. And of course it would also be too tedious for a lazy nerd like me to manually sculpt dents. I was already trying to figure out a procedural approach for this dented look.

What I came up with is relying heavily on Houdini’s excellent implementation of VDBs. VDBs are a really fast representation of voxels. Voxels are for 3D the same as what pixels are for a 2D image. Think of them as tiny cubes. Each voxel can store a Value. In our case the distance to a surface. If a voxel is on the outside, it will store a positive distance towards the surface. If a voxel is on the inside, it will store the negsative distance towards the surface. If we want to convert a volume containing voxels to a surface (polygons) we simply have to find out where the volume’s voxels have a value of 0. This is called an SDF, a signed distance field.

Enough stuff about the theory of voxels in Houdini. Let’s get building!

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11 Comments

  1. Donnie Pitts says

    Wow. That was so straightforward. You guys are killing it! Thank you so much for doing these tutorials. This is going to help a lot of people (myself included).

    Really looking forward to what you guys have in store for the future!

  2. Moritz says

    Thank you! We’re mega excited about this whole thing as well! 🙂 Cheers!

  3. Excellent!
    The fact you explain the technique with a visualisation process (say in illustrator) is really super handy, at least for me and my small brain ;o)

    Thank you again for sharing your great knowledge.
    Awaiting for more.

    Cheers
    Regis

  4. Tiago Cardoso says

    That’s amazing, very nice tut.
    I have just one question, how you have done the render?

    • Moritz says

      Hi Tiago,

      I converted the VDB to a polygonal mesh, scattered points on it and connected them, then converted the resulting splines into polywires. Exported via alembic and rendered in C4D using Octane. Hope that helps,
      Cheers,
      Moritz

  5. Aleksandras says

    This is so awesome, super glad I found about you guys. I tried to avoid Houdini as much as possible because it looked so complicated compared to other 3D packages. Your explanation is really top notch and super easy to follow. The Illustrator part alone makes this tutorial excellent!

  6. kuzy62 says

    Great tutorial….so straightforward and easy to follow!

  7. kuzy62 says

    Can you randomize the size of the spheres that dent the larger sphere? Sorry I am a Houdini beginner….until now I worked totally in Cinema 4D…thanks!

  8. Michele Spaliviero says

    Thank you so much, very helpful!
    Since I don’t have H16, do you think I could use this as a basis to construct the torus to make the “packing the torus” tutorial?

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