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Everything posted by ssh

  1. Ship Kelvin Wake

    Sure. Attaching file for Houdini 17. This should work in Houdini 16 as well. Let me know if something does not look right. ssh_kelvin_wake.hipnc
  2. Hello, Here is short video showing how volumes can be used to shade and texture semi-translucent organic things. Volumes For Organic Assets This approach allows to achieve close-up realistic organic look for semi-transclucent assets where SSS or colored refraction is not enough. An object with UV's is converted to signed distance volume with UVW grid. Then volume is used to set density and perform uv lookup in rendering. This way density can be adjusted by depth. I.e. not so dense near the surface and very dense at the core. Or not very dense, then dense patch like island of fat, then not dense again. UVW grid is used to texture volume. Different textures can be used at different depth. This approach allows very flexible yet powerful way to place any texture at given depth. Texture X at depth Y. I.e. big veins are 5mm under the surface. This approach is best for close up organic hero renders where SSS or refraction are not looking good enough. Attaching example file volumetric_textures_example.hip
  3. Ship Kelvin Wake

    Made an updated version for Houdini 16, should work for H15 as well. Wake deformation done as point wrangle. Get the scene file here: http://www.shlyaev.com/files/hip/ssh_kelvin_wake.hipnc To see source code look onto point wrangle node.
  4. This is proof of concept for simulating water inside of air field. The only difference in simulations is the presence of that air field. Done with standard Houdini flip tools. Inspired by ILM's Siggrpah talk on "Battleship". See the huge difference and much more realistic behavior. Watch it here: https://vimeo.com/57182252
  5. Water inside of air field

    This turned out to be an Orbolt glitch.
  6. 2*pi probably comes from the fact that Mantra expects probabilities expressed in hemispheres as well as other render engines do. Surface area of a full sphere is 4*pi*r^2. Surface area of hemisphere above the shading point will be half of that, 2*pi*r^2. Since it is unit hemisphere, we can ignore r^2. So it is just 2*pi.
  7. Awesome work, Jim!
  8. Microfacet Refractions

    It was done in 2011 for Mantra micropoly. Using ggx bsdf that I've implemented by myself. AFAIK, Houdini does not have this model built-in at the moment.
  9. Microfacet Refractions

    Hey John, That video is actually from Mantra. Edit: I've updated Youtube video's description mentioning that it is Mantra.
  10. Water inside of air field

    That's cool Ian. The other approach to bubbles in the flow may be using reseeding in flip solver. Playing with oversampling settings to get different sampling settings for the surface and interior of the fluid gives cavities as well. That trick is working great in Naiad (https://vimeo.com/47556195 skip to the end of the video).
  11. FLIP with "Air Field"

    Just to add: anyone interested in airfields can download setup from Orbolt. http://www.orbolt.co..._with_air_field Also it was discussed here at Odforce as mentioned by edward: http://forums.odforc...e-of-air-field/ Edit: In terms of simulation speed, latest version of my setup does not add significant overhead for final resolution sims. I.e. when simming tens of millions points it takes same time to compute a frame as without the air field.
  12. Water inside of air field

    This setup is now available via Orbolt asset store. http://www.orbolt.co..._with_air_field
  13. Hello, Just would like to share hair shader I've done. This shader implements well known Marschner model proposed here: http://www.graphics....r-sg03final.pdf Video on Vimeo: http://vimeo.com/18197441 Youtube: Tested both in H10 and H11. Shader Parameters: Diffuse color and intensity. please note that for dark hair diffuse intensity is usually very small Overall specular intensity and color. Computed speculars are multiplied with this values. This parameters are not physically correct and are provided for convinience only. Different light masks and categories lets specify which lights are contributing to diffuse and specular computation. Specular components: Primary Highlight (R ): Strong primary specular peak. Secondary Highlight (TRT): Colored secondary peak. Backlight (TT): Colored component that appears in back lighting situations. That is the bright halo around the hair. Each component has it's own intensity and color multipliers for ease of use and tuning. Shift sets shift amount of speculars from root to tip. Width sets width of speculars. The more the width the wider they are. Usage: 1. Download and Install ssh_marschner_hair.otl (File->Install Digital Asset Library) 2. In SHOP context start typing ssh_marschner_hair_model and choose this shader. Update: There are hairDiffuseExport and hairSpecularExport export variables so diffuse and specular data may be separated. UPDATE: Shader supports texture maps as well as ramps that allows to remap colors and opacity from root to tip. Latest version of the shader is avaliable here: ssh_marschner_hair ssh_marschner_hair.otl
  14. Marschner hair model

    Do not know about the default fur. In my shader they are used for the purposes of light linking. So you can choose which lights are illuminating hair and which are not. Categories are passed straight to illuminance loop inside of shader. For more information on this please refer to the docs: http://www.sidefx.com/docs/houdini12.1/light/lightandshadowlinking#categories http://www.sidefx.com/docs/houdini12.1/vex/functions/illuminance
  15. Marschner hair model

    You need to set light categories in shader as well, so it knows which lights to pickup. Take a look at the attached file. ssh-marsh-light-cat-prob.hipnc
  16. Marschner hair model

    Can you please post an example file so I can check and fix it?
  17. Water inside of air field

    I was working on it for some time. Check it out: https://vimeo.com/60134752 Air is added only where it's needed basing on sdf of main fluid. No bounding box needed. One can control thickness of air shell, amount of air particles, limit air to specific hero regions etc. Also done some extra steps to proper detect droplets with this approach.
  18. Water inside of air field

    As a nice side effect one do not need to do any additional tricks to get better behavior. Which saves fx artist's time a lot. Container, emitter, initial velocity - done.
  19. Water inside of air field

    Time difference is probably caused by the fact that you have to simulate much more particles. Because all the rest of container is filled with air. There might be way to optimize this and have air only where it's needed. I am checking it now. This is just a proof of concept to see how much can we get from this approach.
  20. Water inside of air field

    There is no smoke solver involved. Water and air are simulated with one flip solver.
  21. Water inside of air field

    Thank you Erik, don't think pdfs exist. I know it from the guys who attended it on Siggraph. Thanks, this is very usual Flip setup with density being overrided. Some particles(air) have very low density and some particles (water) have high density. All is simulated in one step. E.g. no need to simulate air first then apply cache to water or anything like that. This is very simple setup.
  22. Water inside of air field

    Thanks, water with air is 2-3 times slower then just water. Worth it.
  23. Ship Kelvin Wake

    More complex(and slower) model. This one takes boat length, width, speed and draught into account. boat_wake.otl ssh_kelvin_wake.hip
  24. Ship Kelvin Wake

    Check the attachment for the simplest case. This is done with vex sop that deforms points of incoming ocean geometry. ssh_kelvin_wake.hip
  25. Hot as a force

    Actually it's Naiad, not Houdini.