[Sidefx-houdini-list] Time warping a point cloud

Pablo Giménez pablogipi at gmail.com
Thu Aug 7 04:14:39 EDT 2008


You can do a time wrap, I use to prefer the time shift, but using a ramp,
and indexing into the ramp.
I have used it recently to retime several animation in base of some stamp
parameter so I can get several copies of teh same animated thing but
retimed, and works really well.
For me it gives more control than using only the cache and because you are
using the time blend you ensure that you get correct results for moiton blur
in case you need it.
Hope this helps.

2008/8/7 Guillaume Laforge <guillaume at alamaison.fr>

> Hi Pablo,
>
> Yes I've got the same number of points but I need to control the time
> warp with an fcurve so "chf" expression to drive the index of a cache
> SOP works better in my case, unless I miss something with the Time Warp
> SOP ?
>
> Cheers
>
> Guillaume
>
> Pablo Giménez a écrit :
> > Hey Guillaume, I don't know if the topology of your point cloud is
> changing,
> > probably yes, but if this is not the case you can use the Time Blend SOP
> > after  a Cache SOP and the you can use Time Warp SOP or Time Shift SOP to
> > retime the animation, it works pretty well.
> >
> > 2008/8/6 Guillaume Laforge <guillaume at alamaison.fr>
> >
> >
> >> Lot of very good advices. I've got much more control on my little points
> >> now :).
> >>
> >> Thanks Ben.
> >>
> >> Cheers
> >>
> >> Guillaume
> >>
> >>
> >> Ben Schrijvers a écrit :
> >>
> >>> And for the time warping... uhm... maybe use an animation curve instead
> >>> of $T  :-)
> >>>
> >>> Ben Schrijvers wrote:
> >>>
> >>>
> >>>> Hi there,
> >>>>
> >>>>  I just gave that a go and you just need to set the geometry CHOP's
> >>>> start and end paramers to $T.
> >>>> In that way it just reads the current frame.
> >>>>
> >>>> With time slicing and things like lag, jiggle etc you can only play
> >>>> forward so I geuss you bring back the channels into sops and render
> out
> >>>> a point cloud sequence again.
> >>>>
> >>>> cheers,
> >>>> benS
> >>>>
> >>>>
> >>>> Guillaume Laforge wrote:
> >>>>
> >>>>
> >>>>
> >>>>> Hellooooww Ben :),
> >>>>>
> >>>>> The timeslicing option sounds interesting but I can't find a way to
> >>>>>
> >> activate this parameter directly in the geometry CHOP.
> >>
> >>>>> It is possible to turn it on in the lag CHOP but the memory could be
> >>>>>
> >> full before this node :-/.
> >>
> >>>>> I'm at home know, so I can't test on my point cloud sequence. I will
> >>>>>
> >> let you know how it works tomorrow.
> >>
> >>>>> Thanks.
> >>>>>
> >>>>> Guillaume
> >>>>>
> >>>>>
> >>>>> On Tue, 05 Aug 2008 20:01:16 +0200, Ben Schrijvers <
> >>>>>
> >> ben.schrijvers at guerrilla-games.com> wrote:
> >>
> >>>>>
> >>>>>
> >>>>>> Bonjourrr...
> >>>>>>
> >>>>>> For the time warping part you indeed are better of with a sop
> method.
> >>>>>> For CHOP's tou might consider looking at timeslicing. Each CHOp has
> a
> >>>>>> toggle in the last tab.
> >>>>>> Not sure if it's documented somewhere but I believe it means it's
> just
> >>>>>> keeping a few frames in memory.
> >>>>>> Not all CHOP's will work but things like lag, jiggle or spring will.
> >>>>>>
> >>>>>> cheers,
> >>>>>> benS
> >>>>>>
> >>>>>> Guillaume Laforge wrote:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>> Hi,
> >>>>>>>
> >>>>>>> I'm trying to do some time warping on a bgeo sequence  of points
> >>>>>>>
> >> coming
> >>
> >>>>>>> from a fluid simulation. I thought that I could use CHOPs to
> control
> >>>>>>>
> >> the
> >>
> >>>>>>> motion but
> >>>>>>> unfortunately when I reference my bgeo file in a geometry CHOP, it
> >>>>>>>
> >> gives
> >>
> >>>>>>> an error or crash Houdini. I've got 7000 points in my bgeo files
> and
> >>>>>>>
> >> a
> >>
> >>>>>>> duration of 120 frames. Maybe it is to much data to handle in CHOP
> ?
> >>>>>>> I tried the Timewarp SOP too but it gives less control than CHOPs
> (no
> >>>>>>> lag, jiggle etc...).
> >>>>>>>
> >>>>>>> Any advices to setup a time warping on a bgeo sequence of 7000
> points
> >>>>>>>
> >> on
> >>
> >>>>>>> 120 frames is welcome !
> >>>>>>>
> >>>>>>> Thanks
> >>>>>>>
> >>>>>>> Guillaume Laforge | la maison
> >>>>>>> _______________________________________________
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> >>>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
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> >>>>>>
> >>>>>>
> >>>>> --
> >>>>> Guillaume Laforge | la maison
> >>>>>
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-- 
Un saludo
Best Regards
Pablo Giménez



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