The final word on nCloth Space Scale

#1

Hopefully someone can definitively answer this question about the ‘intended’ and/or 'correct ’ workflow for nCloth in Maya 2015. I have a ton of experience with nucleus stuff but I guess I missed the day when what seems like some essential info was passed around. It would be great to get confirmation on this.

In the 2009 white paper for nucleus it’s documented that the best practice, when working in default Maya scale (cm), is to change the Space Scale attribute on the nucleus to 0.01.

  1. Set Space Scale on the nucleus node based on
    one’s unit settings. If one modeled in meters,
    set it to 1.0, but if one modeled in the default
    centimeters, set it 0.01. The main effect is to
    set gravity to the correct amount, as dynamics
    in Maya always interprets units as being meters
    regardless of the units setting.

Is this still the expected workflow? I’ve delivered many projects with the Space Scale at the default of 1. So many such projects that one of our senior TD’s asked me for some advice about setting up a sim and one of the first things I mentioned was that his Space Scale being at 0.01 was a bold choice. Then he pointed me to the white paper.

This would be great to get confirmation on. I love learning new tips. But it is a bit crazy that the default scale of Maya (cm) is not reflected uniformly throughout the application.
Of course I get that Dynamics are interpreted in meters, but I assumed that the default Space Scale attribute was taking this into consideration. I feel that this attribute should really be set to 0.01 by default since that is the needed setting when working in Maya’s default unit scale. It just makes sense…at least to me.

Thanks in advance for any tips.
~Ben

#2

The classical maya dynamics were interpreting units as meters (primarily for gravity) and thus this was retained for nucleus for backwards compatibility. The actual Maya unit setting (cm is the default) was ignored.

At any rate pretty much the only thing affected currently by the space scale is gravity. Thus a scene scale of 0.01 is equivalent to a gravity of 980.0. If you don’t change either the gravity or the scene scale then a scene in cm will have much too low gravity.

Also lift should be affected by space scale, but currently is not, so for large scale scenes one should use very small lift values to avoid artifacts. (usually I start with it at zero then increase until the desired effect is produced)

Things like field dropoffs are also part of the classical dynamics and not affected by space scale so one needs to adjust field magnitude based on scale and dropoff in a similar fashion to the decay from lights.

Duncan

#3

Amazing Duncan. Just the man I was hoping to hear from.
That clarifies everything. I usually ended up with gravity of 980 when doing gravity based stuff. That makes sense, since I had been leaving the Space Scale at 1.
Great tip about Lift too. There is always more to learn!
Thanks so much for the info.
Can’t stress enough how great it is that you keep in touch with us here!
~Ben