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

Guillaume Laforge guillaume at alamaison.fr
Thu Aug 7 05:29:35 EDT 2008


>... 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.


I don't understand why you need a Cache Sop before the Time Blend ?

If I understand well,  the difference with the Time Blend and the Cache 
is that the Time Blend interpolate also the velocity attribute ?


Guillaume


Pablo Giménez a écrit :
> 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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>>>>>>>>> Sidefx-houdini-list at sidefx.com
>>>>>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>                   
>>>>>>>> _______________________________________________
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>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>                 
>>>>>>> --
>>>>>>> Guillaume Laforge | la maison
>>>>>>>
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>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>               
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>>>>>>
>>>>>>             
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