[Sidefx-houdini-list] Maya .anim curves in Houdini

Andrew D Lyons tstexture at gmail.com
Wed Feb 21 20:29:41 EST 2007


Talking to Edward off list, (sending screen snaps of CHOP viewer etc)
he's pointed out that my test animation channel has values ranging
across 230 units - so my 0.01 unit deviation in percentage terms is
really only 0.0000043%

Looking at it that way I guess it's not so bad.

Still - Doubles!!!

Cheers


On 21/02/07, Ivan DeWolf <ivan at martian-labs.com> wrote:
>
> if you're dumping the data to an ascii file, that might be the precision error.
>
> often it seems ascii dumps of floating point numbers are truncated...
>
> Quoting Edward Lam <edward at sidefx.com>:
>
> > Hi Andrew,
> >
> > Andrew D Lyons wrote:
> > > Before I look into writing new curve functions for Houdini, I just
> > > want to find out if anyone used this math to get super precise
> > > results?
> >
> > That I don't really know as I was only told that it worked after I gave
> > someone the math. :)
> >
> >  > I'm not sure where the problem is at this point. I'm using
> >  > the mel xform function to sample values out of Maya to do comparisons
> >  > in CHOPs. Maybe it's there?
> >
> > The equations rely on tan() so it's possible to get precision error. There's
> >
> > also the issue that Houdini only deals with single precision float's in
> > channel so depending on your values, you might also be running into that.
> > Make
> > sure you're performing the formulas in double-precision?
> >
> > -Edward
> >
> > > On 21/02/07, Edward Lam <edward at sidefx.com> wrote:
> > >> I helped someone do this before as well. The formulas for cubic
> > >> interpolation
> > >> can be found here:
> > >>
> > >> http://odforce.net/wiki/index.php/KeysToHoudini
> > >>
> > >> -Edward
> > >>
> > >> Lucio Flores wrote:
> > >> > I wrote something like that at DD years ago. YOu need something to
> > >> dump a text
> > >> > version of the keyframe data onto disk. Most animation channels are
> > >> just cubic
> > >> > hermite or bezier functions, so its just a matter of getting the
> > >> > slope/time/value info, and correctly translating that into houdini.
> > >> Some
> > >> > packages have the slope derivative as value per frame, or value per
> > >> second, so
> > >> > there may be a fps multiplier in there. Using that was enough to
> > >> translate
> > >> > keyed channels between softimage, lightwave, maya, and houdini.
> > >> >
> > >> > --- Andrew D Lyons <tstexture at gmail.com> wrote:
> > >> >
> > >> >> Hi,
> > >> >>
> > >> >> Have any studios successfully found a way to accurately convert Maya
> > >> >> keyframes into Houdini keyframes?
> > >> >>
> > >> >> If so - how was it done?
> > >> >>
> > >> >> My current guess is that we would need the HDK to replicate Maya's
> > >> >> curve functions as Houdini curve functions. Not sure if there is other
> > >> >> keyframe infrastructure needed though as well...
> > >> >>
> > >> >> Cheers
> > >> >>
> > >> >> --
> > >> >>
> > >> >
> > >> > -------------------------------------------
> > >> >
> > >> > God, how much more profitable would it be,
> > >> > if the Thinker would learn from the Drunk?
> > >> >
> > >> >                                    - Kafka
> > >> >
> > >> >
> > >> >
> > >> >
> > >>
> >
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>
> -Ivan
>
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-- 
=======================================
Andrew D Lyons | Digital Artist | http://www.tstex.com
=======================================



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