Houdini Units + Flip Simulation

[catchyid]

Hi,

I am importing an alembic cache where objects don't have realistic dimensions, i.e. the height of one character is 8.99 units (i.e. if I use bound node, I will get a size of 9 x 8.99 x 3). Since I cannot scale down the imported alembic cache, I need to adjust Houdini such that each unit length in the scene is 0.2 meters, hence a 8.99 tall character will be 1.798 meters only. This is needed because I am doing FLIP simulation in the scene and I want the simulation to look realistic. I have two questions:

1- does setting Houdini Preferences -> Hip File Options -> Unit Length (m) to 0.2, is the right way to do that? plz see attached image

2- Even when I did the above steps, FLIP particle simulation does not change!!! Meaning, I was excepting FLIP particles to flow faster (because each Houdini unit is actually 0.2 meter), however particles flow has not changed (i.e. same speed, they moved the same distance...)???

Thanks,

 

[Skybar]

Why cant you just scale the character down? It will save you a lot of headache. Then afterwards, if you need to, you can simply scale the simulation back up. This is usually how its done in production. 

[Sepu]

Yep just agreeing with David here, you def do not want to change units in Houdini, it will get messy. As David mentioned just scale down your character by .1 or .01 depending your program, but usually for Maya that is what I do, then export the sim and scale it up. 

Usually you do not want to change the unit measures in any 3D software, for dynamics. 

[Guest tar]

So you need to change the preference scale then create the dop objects. All it does is multiple the values like gravity, particle separation etc.

You can test it easily by set the unit length to 1, create a gravity node, then set the unit length to 10, create a gravity node. and the vales will be -9.80665 & -0.980665 respectively.

[catchyid]

Alright guys, I'll do as you suggested  Thanks Marty for explaining how it works, I've tested and it works as you said