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amm

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amm last won the day on March 29

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    Anto
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  1. By the way I've tried what I've suggested, and... really problematic part seems to be building the per-point orientation, somehow it is always arbitrary. So at the end of the day, three stages are minimum to build an curve based interpolation, as an robust method, just like you did , I guess. If I'm correct, there's something for preserving the curve segment's length in your method, like Maya curve 'lock length'. About ready for use solvers, while ago I've played with RBD constraints and Bullet, as an replacement for H wire solver, it showed great self-collisions, but entire sim was a bit too wild, more like ropes - 'loose' SDF based collision in Wire solver looked more realistic. H 'connect adjacent pieces' wasn't enough for building the relations (it takes nearby points in 3d space), had to build the replacement of 'connect...' thing. Other than that, VDB Advect or FEM soft body comes to mind, however there's too long way of forth-back conversions with both (for my taste) to use as rigging tool.
  2. If both stages are given, just for something like that, should be possible to get the angle by comparing the normals, also a line between two stages. These two, line and angle, should be enough elements to calculate the center of rotation by using some triangle formula (of right triangle). Cross product of normals (at first and last stage) should be a rotation axis. While entire thing will be rotating inward, unless you'll lower the ambition to less than 180 degree between stages. Not in front of Houdini, anyway I'd believe it will work. Multiple stages would be interesting to get by some SLERP , while this a bit too much for me to visualize, right now...
  3. Fusion Studio

    Well, people are usually going in opposite directions in last ten years or so, toward After Effects or Nuke, depending of what they are doing. Should not be hard to get into basics, however in my opinion, it's really old fashion app, full of specific solutions from 90s. Starting from numerical inputs where you are able to use sliders somewhere, somewhere not, somehow unusual choice of blending modes, different behaviors of copy - paste node, so on. Let's say if you want to re-create something like (not built-in) light wrap effect by nodes, that would be a way easier and straightforward in Blender compositor. While generally, Natron is much more Nuke - like, also, Natron provides you controls where you expect to find them, well at least for my taste. Nodal or not, I think After Effects is a way more unified app, making it easy to just override disadvantages of layers, in many cases. I'd say, if there is a particular advantage of Fusion, use it just for that. However, complete switch is hard to imagine, actually it sounds impossible.
  4. imported UVs

    Generally, if they are on vertices, keep them there. UV as vertex attribute makes possible to have "breaks" between UV islands, even on connected polygons, hard edge in case of normals, also ''per polygon'' vertex color (vertex color in case of FBX). Once they are promoted to point, you'll get UV connected all around, let's say between first and last UV edge of cylindrical UV map, so on. That's not what you want. In other word, promoting from vertex to point has sense only if each UV island edge is corresponding to polygon boundary edge. Why that difference is happening, I don't know, my wild guess is that Houdini performs some kind on optimization on import, if it is possible to promote UV or normals form vertices to points harmlessly , H will do that, otherwise it won't (I could be wrong for this 'who is doing that' part).
  5. OBJ transform to SOP lvl

    Wouldn't hurt. By the way, does anyone have some experience with SideFX GoZ for Houdini.
  6. OBJ transform to SOP lvl

    Not all the time. If you're using exporter from file>export menu, then yes, positions are baked into global space before exporting, in case of obj file. In case of FBX, it writes both, global and local. Same with Maya. However if you write something out using ICE Cache On File node, it's local position. If you take a Houdini File SOP as equivalent of ICE Cache On File node, it should be clear what happens. SOP VOP deformation, as well as ICE tree, is applied in local (object) space.
  7. OBJ transform to SOP lvl

    As far as I know, Obj format does not store any transforms at object level, there are point positions in global space and that's it. On Softimage - Maya - Houdini route, default up axis is same Y, result should be the same, as you already noticed. Most likely, zBrush did something according to its preferences or something else, these zBrush arbitrary changes are somehow traditional. Just for info another app with similar habits is Blender (because of Z up). If adjusting zB preferences doesn't help, should be enough to use Transform SOP, that's relative cheap, all at once deformation. If Houdini is able to display the mesh, should be able to evaluate Transform SOP, too.
  8. Distance from center in shops

    Well, then something else went wrong. From my small experience, it works....
  9. Distance from center in shops

    Should be something like in pic. That's SHOP, ''current'' space is camera.
  10. So here's attempt First of all, this is not an universal skin shader, exact replica or anything like that, I just tried to put some typical 'contemporary' methods into network. It is a mix of PBR Diffuse, PBR Single Scatter ( introduced in 16.5), and two PBR Reflections. It should showing what is possible to do, feel free to experiment with nodes inside shader network. There's just one subsurface scattering shader in mix. Houdini PBR Single Scatter has all map-able attributes, like scattering distance or attenuation color (while in old Mental Ray's Fast Skin, blurring radius is not) - things like exaggerated back scatter around ears or variances in attenuation color, are performed by simple trick: point color is used as mask for modulation. One SSS shader should be much faster to render than three, obviously. So at the end of the day, only typical Mental Ray's Fast Skin feature is screen blending of layers. I added switches between screen blend and plain additive. Important parameters: - Diffuse and SSS tint: that's 'modern' method, to multiply diffuse and SSS texture by complementary color, diffuse in light blue, SSS in orange. Overall is nearly the same as original color of texture, while complementary colors are there to get stronger diffuse - SSS difference. - Diffuse and SSS power: actually a gamma value, 1 is original, more than 1 is exaggerated darker color. - Diffuse and SSS Weights: for more of 'old paintings' style, feel free to raise the SSS weight. - Screen blending, Diffuse vs SSS, Reflections vs Diffuse and SSS: feel free to disable them just to see what happens. Nice side effect of screen blend is clumping of maximum direct lighting ( inside shader I set this to 1.25), making it easier to sample by Mantra. - Two reflections, first is wide, it acts more like additional diffuse shading. Second is sharp, intentionally disabled at edges. Bu some convention, shading model is set to Phong, as Phong does not fade the wide reflections (contrary to GGX) - so somehow Phong fits better, here. Any reflection parameter is a subject for tweaking, except maybe just one: in case of skin, it's always blueish tone, AFAIK that's natural effect of exaggerating the complementary reflection color in case of scattering media, something not automatically set by layered shading used in renderers like Mantra. Regarding wikihuman files, I've reduced resolution of bitmaps to make a smaller download, also I've used only three maps: diffuse color, specular color, and main displacement. Get files (around 30 Mb) there.
  11. I'd try to post Houdini scene this weekend, based on wikihuman files. Regarding Lee Perry's head, I'd say, enough is enough :).
  12. Hello McNistor, just a few thoughts: 'edge factor' in Mental Ray's fast skin (and default reflection falloff in all variances of MIA) could be a kind of very simplified Fresnel effect, precisely number 5 is exponent of dot product of shading normal and negated eye direction. In H, that could be 'normal falloff' node with mentioned exponent of 5 (or a bit more or less), plugged into 'fit range' node, where 'destination min' and 'destination max' are facing - edge weight, all that used to fade the reflection. That's simplified but gives a cleaner control over reflection weights than 'true' Fresnel. With unmodified 'fit range', it's zero at facing and one at edge. For subsurface shaders introduced in H 16 (honestly I don't know what is included in Principled thing), I'd definitively go to 16.5. Ones in 16 are utilizing indirect rays (while in 16.5 this switched back to direct) - so, I'm afraid, everything you'll be able to get with 16.0 versions, could be a long forum thread about long render times, fireflies and such. Unfortunately, there is no control over reflection color and face-edge weighting in H Skin shader, which makes it close-to-unusable. Why is that, I have no idea. PBR story should not be excuse for such brutal approach, IMO. IOR/Fresnel is present, but without precise facing/edge weighting control. Regarding Mental Ray's fast skin, 'subsurface' is actually based on wild approximations, it's baked diffuse shading to vertices and blurred later, that's why there's need for three layers. Anyway, author had a great artistic talent to get a good look out of all that. One important 'artistic' element is under 'advanced' tab, it is screen blending of layers, not plain additive, which helps to avoid 'burning' with strong lighting. That's in short. Last few months I've played a lot with this subject , basically I was able to get what I wanted. However, solution probably is not suitable for sharing all around. Anyway, it's possible to re-create a 'Master Zap's style' of shader components mixing in H. If anyone wants this, I'll be happy to help.
  13. Help With Speeding Up Render

    In case of glass, there's old trick utilized in some custom Mental Ray shaders, to distribute sampling, reflection *or* refraction, which on is more prominent for certain pixel. Worked well ten years ago, using machines of these times. Don't know what happens there, anyway result is really bad and unexpected. I've also tried your scene, tonight.
  14. Leaf Shader - How to get realistic translucency?

    Perhaps something like this. It is PBR Diffuse in translucency mode, 'shade both sides as front' is disabled. I think it should go as additive on top of some usual shader, as it seems it shades only opposite side of light. Alone is not enough.
  15. Smoothing Lighting in Material

    How about some light with soft shadows, that is, anything else than point or distant light. Another that comes in mind is blend based on luminance, instead of switch. Let's say 'fit' node with luminance as input, source max to something like 0.1, fit node as input of bias of color mix . Third option could be some subsurface shader (could be slower...) - some SSS shaders are based exactly on blurred diffuse shading, while I'm not sure does it apply to ones in Houdini. From my understanding, dealing with normals won't affect the terminator edge (that's old school name for edge between illuminated and no illuminated area). In case of lights with sharp shading and shadows, that's always sharp edge, while shading based on normal is able to smoothly fade the shading, down to zero on terminator edge - but not to change it.
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