[Sidefx-houdini-list] DOPS and scale

Alex Czetwertynski disciple1 at gmail.com
Tue Jan 18 17:13:12 EST 2011


Yes, it makes sense that there should be a unit measure.  Good to know the good old metric system is the one to use, I still haven't gotten used to feet and inches :)
Thanks
Alex

On Jan 18, 2011, at 2:08 PM, Robert Kelly wrote:

> woops I see you said what not why.....
> 
> there are plenty of values that are sensitive one way would be to make
> some shelf smoke as cm and another as meters and compare the values on
> them.
> 
> On 18 January 2011 14:06, Robert Kelly <isstuff at gmail.com> wrote:
>> you fall at a rate of 9.8 m/s² if your unit scale is  1 unit = 1 meter
>> then you put in your gravity force 9.8
>> BUT !
>> if your unit scale is 1 unit = 1 center meter other wise known as 1
>> unit = .01 Meters then your gravity force gets a value of 980.
>> 
>> There are other real world values that are unit sensitive.
>> 
>> http://en.wikipedia.org/wiki/Equations_for_a_falling_body
>> 
>> On 18 January 2011 13:50, Alex Czetwertynski <disciple1 at gmail.com> wrote:
>>> Thanks for the answers...
>>> 
>>> What nodes are scene unit sensitive?
>>> 
>>> Thanks
>>> Alex
>>> 
>>> On Jan 18, 2011, at 1:46 PM, Robert Kelly wrote:
>>> 
>>>> if your doing DOPs you want to set your unit scale before putting down
>>>> any DOP nodes. They change values on the nodes that are scene unit
>>>> sensitive on creation. So if your not careful you can make a scene
>>>> with some values made for meters and some set for center meters.
>>>> 
>>>> On 18 January 2011 09:08, Michael K. O'Brien <mobrien at pixar.com> wrote:
>>>>> Hola~
>>>>> 
>>>>> There are several constants in physics simulations that have dependencies on
>>>>> distance that aren't exposed (like damping factors). If you try to do really
>>>>> large or small scale simulations, float precisions starts to creep in as
>>>>> well.
>>>>> 
>>>>> We usually scale the world down so something that is 1 unit == 1m when
>>>>> possible. We've had problems with changing the units.
>>>>> 
>>>>> MO
>>>>> 
>>>>>> -----Original Message-----
>>>>>> From: sidefx-houdini-list-bounces at sidefx.com [mailto:sidefx-houdini-
>>>>>> list-bounces at sidefx.com] On Behalf Of Peter Bowmar
>>>>>> Sent: Monday, January 17, 2011 8:19 PM
>>>>>> To: sidefx-houdini-list at sidefx.com
>>>>>> Subject: Re: [Sidefx-houdini-list] DOPS and scale
>>>>>> 
>>>>>> I believe 1 unit defaults to 1 metre and 1 weight unit is Kg (forget
>>>>>> exactly). It's in the Preferences->Miscellaneous section. So the
>>>>>> "smaller object" would have lower mass and therefor less force
>>>>>> required to accelerate it.
>>>>>> 
>>>>>> Unless I've really badly forgotten my highschool physics :) in which
>>>>>> case I blame the antibiotics...
>>>>>> 
>>>>>> Cheers,
>>>>>> 
>>>>>> Peter B
>>>>>> 
>>>>>> On 17 January 2011 19:00, Alex Czetwertynski <alex at franktheplumber.com>
>>>>>> wrote:
>>>>>>> When modeling objects to be used in DOPS, does one have to pay
>>>>>> attention to scale?  I noticed a wind force had a much stronger
>>>>>> influence on a smaller object, but I'm not sure what the rule of thumb
>>>>>> is in terms of getting things to be in a good mid-range?
>>>>>>> staying within the range of the initial grid maybe?
>>>>>>> 
>>>>>>> Thanks
>>>>>>> Alex
>>>>>>> _______________________________________________
>>>>>>> Sidefx-houdini-list mailing list
>>>>>>> Sidefx-houdini-list at sidefx.com
>>>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> --
>>>>>> No, I am not on Facebook.
>>>>>> _______________________________________________
>>>>>> Sidefx-houdini-list mailing list
>>>>>> Sidefx-houdini-list at sidefx.com
>>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>> 
>>>>> _______________________________________________
>>>>> Sidefx-houdini-list mailing list
>>>>> Sidefx-houdini-list at sidefx.com
>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>> 
>>>> _______________________________________________
>>>> Sidefx-houdini-list mailing list
>>>> Sidefx-houdini-list at sidefx.com
>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>> 
>>> ---
>>> http://www.disciplefilms.com
>>> http://www.aenhancers.com
>>> 
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> Sidefx-houdini-list mailing list
>>> Sidefx-houdini-list at sidefx.com
>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>> 
>> 
> _______________________________________________
> Sidefx-houdini-list mailing list
> Sidefx-houdini-list at sidefx.com
> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list

---
http://www.disciplefilms.com
http://www.aenhancers.com







More information about the Sidefx-houdini-list mailing list