[Sidefx-houdini-list] Curves normals

Olex P hoknamahn at gmail.com
Tue Aug 31 06:42:47 EDT 2010


H11.0.446 is fine.

2010/8/31 Pablo Giménez <pablogipi at gmail.com>

> 2010/8/31 Olex P <hoknamahn at gmail.com>:
> > Hey Pablo,
> >
> > Was it you asking about IPR and fur rendering? Something about IPR
> getting
> > stuck on the kd tree generation stage. Could you try the same scene but
> with
> > BVH (ta-dam we have it now!) instead of kd tree (Mantra ROP, Rendering
> tab,
> > Ray Tracing Accelerator parameter). Construction of BVH should be way
> faster
> > than of kd tree plus it could be less expensive in terms of memory
> > consumption. Maybe it could solve your problem.
> Hey Olex, what version of housdini I have to use?
> I only have 11.0.446.9 at the office
> >
> > 2010/8/31 Pablo Giménez <pablogipi at gmail.com>
> >
> >> 2010/8/28 Szymon Kapeniak <szymon.kapeniak at gmail.com>:
> >> > 2010/8/28 Peter Bowmar <pbowmar at gmail.com>:
> >> >> Indeed, there is a new property that turns on/off shading curves as
> >> >> surfaces. I don't remember what it's called though...
> >> >
> >> > ..."vm_curvesurface" as mentioned previously, but as far as I
> >> > understand Pablo's problem was, that even with this property turned
> >> > on, early build of Mantra H11 didn't create "s" variable for hair (I
> >> > can't verify this though). With H11.0.485 all seems to be fine.
> >> Yes, that was the problem, but now seems to be working in latest daily
> >> built.
> >> >
> >> > Anyhow, this optimization is interesting, I made some test renders
> >> > yesterday comparing H10 and H11 with Marschner, Arno Zinke nad
> >> > Houdini's default textured hair shaders. It seems to work well both
> >> > for rendering speed and memory footprint but also has a huge impact on
> >> > fur quality in a middle to close-up shots. No elliptical hairs shape,
> >> > flat less vivid speculars, less distinctive hairs in a far field
> >> > scenario.
> >> >
> >> >
> >> >
> >> >
> >> >>
> >> >> On 28 August 2010 01:34, Louis Dunlevy <louisdunlevy at gmail.com>
> wrote:
> >> >>> actually I betcha it's just a new default rendering parameter for
> that
> >> >>> optimisation that was mentioned earlier, you can probably switch it
> >> back
> >> >>> to the old method..
> >> >>>
> >> >>> On 08/28/10 00:58, Pablo Giménez wrote:
> >> >>>> Yes definitely seems to be a bug in H11.0.446.9 , yes you got it is
> >> >>>> the current production version!
> >> >>>> Latest daily build work well and creates the s coordinate properly.
> >> >>>> H10 also works fine.
> >> >>>> Just in case somebody else is havign a similar problem.
> >> >>>>
> >> >>>> 2010/8/26 Louis Dunlevy<louisdunlevy at gmail.com>:
> >> >>>>
> >> >>>>> parametric s should not be zero. If it is, I'm thinking it may be
> a
> >> bug
> >> >>>>>
> >> >>>>> On 27/08/10 03:02, Pablo Giménez wrote:
> >> >>>>>
> >> >>>>>> Hi Andrew.
> >> >>>>>> I have done similar things for other stuff, but my problem is
> that
> >> the
> >> >>>>>> s coordinate is constant 0 for all the points in the curve
> geometry.
> >> >>>>>> The t is fine, going from 0 to 1 along the curve lenght, but s is
> >> >>>>>> supposed to be along the curve "cross sections" width, and this
> is
> >> not
> >> >>>>>> happening.
> >> >>>>>> With a proper s coordinate along the width of the curve would be
> >> easy
> >> >>>>>> to fake a rounded look.
> >> >>>>>> cheers
> >> >>>>>>
> >> >>>>>> 2010/8/26 Andrew D Lyons<tstexture at gmail.com>:
> >> >>>>>>
> >> >>>>>>
> >> >>>>>>> I did this recently to generate fur sprites. If you get the
> curve
> >> >>>>>>> tangent and stack some cross products with another version of
> the
> >> >>>>>>> curve with normals hard coded to point towards the camera (or
> some
> >> >>>>>>> cardinal axis) then you should be able to derive a normal that
> is
> >> >>>>>>> always pointing in a general direction - but which follows the
> >> >>>>>>> contours of the curve.
> >> >>>>>>>
> >> >>>>>>> 2010/8/26 Pablo Giménez<pablogipi at gmail.com>:
> >> >>>>>>>
> >> >>>>>>>
> >> >>>>>>>> Hi.
> >> >>>>>>>> I am rendering some poly lines as curves, using the 'width'
> >> attribute
> >> >>>>>>>> to control every filament width.
> >> >>>>>>>> That's all right.
> >> >>>>>>>> Problem is that this geometry is created at render time and the
> >> >>>>>>>> normals and texture coordinates are a little bit odd.
> >> >>>>>>>> My main problem is that Mantra creates the needed geometry
> using
> >> the
> >> >>>>>>>> width attribute but seems that is only shading the original
> curve
> >> >>>>>>>> attributes.
> >> >>>>>>>> I mean the hair geometry is created extendin the shaded point,
> >> >>>>>>>> perpendicular to the point of view, and the new geo seems to
> use
> >> the
> >> >>>>>>>> same shading as the original point.
> >> >>>>>>>> Is similar to what happens with points rendering, where the
> point
> >> is
> >> >>>>>>>> shaded once, and then all the geometry created at render time
> >> around
> >> >>>>>>>> the origian lpoint use the same shading from the original one.
> >> >>>>>>>> So you don't have proper normals to make for instance a diffuse
> >> >>>>>>>> lighting that gives you some "rounded" look.
> >> >>>>>>>> I have tried the hairNormalVOP, creating my own tangents,
> created
> >> >>>>>>>> texture coordinates with s going along the hair line from 0 to
> 1,
> >> but
> >> >>>>>>>> the normals I got are just pointin towards camera, they are not
> >> doing
> >> >>>>>>>> the "Rounding2 effect that is suppose to do this operator.
> >> >>>>>>>> So is there any way to go away from the planar look of curves
> >> shading,
> >> >>>>>>>> any way to have sense whre you shading point is in the new
> created
> >> >>>>>>>> gemetry so you can for instance fake normals o apply any othe
> >> rtrick.
> >> >>>>>>>> Thanks
> >> >>>>>>>> --
> >> >>>>>>>> Un saludo
> >> >>>>>>>> Best Regards
> >> >>>>>>>> Pablo Giménez
> >> >>>>>>>> _______________________________________________
> >> >>>>>>>> Sidefx-houdini-list mailing list
> >> >>>>>>>> Sidefx-houdini-list at sidefx.com
> >> >>>>>>>>
> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >> >>>>>>>>
> >> >>>>>>>>
> >> >>>>>>>>
> >> >>>>>>>
> >> >>>>>>> --
> >> >>>>>>> =======================================
> >> >>>>>>> Andrew D Lyons | Digital Artist | http://www.tstex.com
> >> >>>>>>> =======================================
> >> >>>>>>> _______________________________________________
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> >> >>>>>>>
> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >> >>>>>>>
> >> >>>>>>>
> >> >>>>>>>
> >> >>>>>>
> >> >>>>>>
> >> >>>>>>
> >> >>>>> _______________________________________________
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> >> >>>>>
> >> >>>>>
> >> >>>>
> >> >>>>
> >> >>>>
> >> >>>
> >> >>> _______________________________________________
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> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> No, I am not on Facebook.
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> >> >>
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> >> >
> >>
> >>
> >>
> >> --
> >> Un saludo
> >> Best Regards
> >> Pablo Giménez
> >> _______________________________________________
> >> Sidefx-houdini-list mailing list
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> >> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>
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>
>
>
> --
> Un saludo
> Best Regards
> Pablo Giménez
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