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About kelvincai

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    Los Angeles, CA

    FX were sim in Houdini and Maya (FumeFX). Fire rendered in Mantra and deep comp in Nuke with hard surface rendered in Arnold.
  2. Gridless advection

    The characteristic map might be the next step, to solve io bottleneck?
  3. rendered a dcm .exr from h13. However, the .exr is black in nuke8v1. In mplay, the .exr is not black. In nuke8, the DeepSample node could display sample data. Using iinfo dcm.exr, the WorldToCamera and WorldToNDC matrices are all zero. Is it a bug? File: ./dcm.exr (OpenEXR format) Resolution: 1920 x 1080 Pz: Data: 32 bit float Color Model: Single Channel Channel Depth: 32 x 1 (32 bpp) Of (r,g,: Data: 16 bit float Color Model: RGB Channel Depth: 16 x 3 (48 bpp) C (r,g,: Data: 16 bit float Color Model: RGB Channel Depth: 16 x 3 (48 bpp) A: Data: 16 bit float Color Model: Single Channel Channel Depth: 16 x 1 (16 bpp) Depth-Complexity: Data: 16 bit integer Color Model: Single Channel Channel Depth: 16 x 1 (16 bpp) Format Specific Information: Image Type: Deep Compression: zips Comment: none Created: 2014:01:29 17:37:13 Depth Interpolation: discrete Samples Composited: true WorldToCamera: [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] WorldToNDC: [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
  4. Exr data window h13

    Possible to have exr data window in H13? Or mantra still can't do it? I remember in R+H we could have data window from mantra for the proprietary image format.
  5. MPM Solver - Multiphysics

    Trying to implement a MPM solver. DOP first for sure. Prob. need to HDK once proof of concept. Anyone had attempted? If so, any advices would be greate.
  6. My linear algebra is a bit rusty now. But I think if you got the velocity vector (V) and the original point world coordinate position (P0), P0+V = P1, you get the next point world coordinate position (P1). Sorry if I didn't interpret your question correctly.
  7. Any sprite or smoke shader out there?

    You gotta use Rest Position before the isoOffset node to make the noise not to swim in billowysmoke material. Upping the step size and sampling number also smooth the noise. There is a spirteFog material in the Material Palette.
  8. mia_material VOP OP

    Hi Stu, Thanks for the input. BSDF is a PDF itself, while PDF is a more general term which could apply to statistics and other fields. What we need might be only a Ward BSDF, which we might be able to manipulate to match mia. Another advantage of custom BSDF is that we could use measured data from the labs, so that we don't even have to shade and match the physical materials in real world (lack of artistic freedom though). Anyway, I didn't have time to look at it further yet, neither does production demand it. Let's wait till 11 and see if we are freed then.
  9. why use renderman monolithic shaders?

    In Slim, you could share the nodes and reuse the networks. In RfM, it translates Maya shading nodes and networks pretty good. In 3delight, it even translates mental ray shading nodes and networks. But, I agree that RenderMan doesn't have as much advanced shaders (ie. mia_material) off-the-shelf as mental ray.
  10. why use renderman monolithic shaders?

    RenderMan's approach is actually more flexible and efficient than mental ray, VRay, etc approach, for a large scale production. For Arch and/or other smaller scale projects, which shading, lighting, rendering and comp are done by one or few artists, mental ray and VRay approach is simpler and more convenient. In a large scale production, most often the off-the-shelf shaders from both RenderMan and mental ray are not sufficient for the entire production, and most often new and/or new functionality of current shaders will have to be implemented and improved. The only way to write new shaders for mental ray and VRay is in C/C++ via their API. Writing shaders in C/C++ is much harder and troublesome than writing shaders in RSL, and C/C++ compiled code is platform dependent which is harder to maintain for render farms. In addition, RenderMan offers much more extendability via DSO etc, than mental ray API. From simple shaders, using Slim is as simple as using Hypershade or alike. For complex or cutting-edge shaders of large production, studios could have resources to have dedicated shading TDs and programmers to implement the shaders. Forgot to mention, you could write mental ray shaders in MetaSL. I don't know if VRay has any equivalent. But MetaSL is not production proven yet, and not as mature as RSL. Arnold will have its SL too once it is out.
  11. Materials & Shaders

    Study the shader(s) you have at hand, via its VOP networks or VEX codes. Then add the functionality you need, if the shader(s) doesn't provide it. And, it is not so hard to write a new shader from scratch too. It is so much easier to write VEX/RSL shaders compared to mental ray or vray shaders.
  12. mia_material VOP OP

    Latest version I am using on my reel. Sorry that I didn't update the shader for awhile. I am spending much time working on my reel and only develop the shader when I need to. 1. Fixed a bug of thin wall and fresnel refraction. It might happen because of different implementation of 3delight and VEX of fresnel(); 2. Added ray level and threshold control of reflection. Threshold control is hidden though as I didn't fully test it yet; 3. Added translucency (mia_material style, so it is only approximation. Use SSS if you want accurate translucency); 4. Added diffuse, specular, reflection, refraction, etc, export variables, for extra image planes output. A test render of this shader in a production scene with v_gilight and HDRI reflection environment. VOPArchitectural.otl
  13. Materials & Shaders

    You could assign groups on the geometry via Group SOP and assign different shaders via a Material SOP. If the geometry doesn't give you straight lines, you could assign UVs and use texture maps. If the shader you using doesn't take textures, you have to add the textures function by yourself in VEX/VOP or use other shaders which take textures. These are about what I can think of for now.
  14. Volumetric Motion Blur

    I had little success rendering volume/metaball motion blur, beside the i3d motion blur option in image3d gen or post/comp. Are there any other ways to render motion blur for volume? And, can or how the new Pyro render with motion blur? Thanks,
  15. Houdini Fur shader mod to Kajiya Kay

    check the prman.h in $HFS\houdini\vex\include there is a section in help for converting RSL codes to VEX. They are very similar.