Forums Technical Discussion Cloth Mass Density Unit?

Cloth Mass Density Unit?

   5260   8   1
User Avatar
Enivob
Member
2631 posts
Joined: 6月 2008
Offline
 
Does anyone know what units cloth mass density are in?

The tool tip claims “This is the amount of mass per volume.”

What does this mean?
How do I relate this value to the size of my piece of cloth?
Using Houdini Indie 20.0
Windows 11 64GB Ryzen 16 core.
nVidia 3050RTX 8BG RAM.
 Report
User Avatar
symek
Member
1390 posts
Joined: 7月 2005
Offline
 
My guess is that it's density of a matter per unit volume, which is cubic meter in Houdini:

1000cm3 of water weights exactly a ton, because density of water is…, well, 1000kg/m3

In case of cloth:

cloth_weight = area of the polygons * thickness of the cloth * material density.
Edited by symek - 2017年10月12日 20:54:58
 Report
User Avatar
Enivob
Member
2631 posts
Joined: 6月 2008
Offline
 
Hmm..I still don't understand what the units are, even if I solve the equation.

Using the equation let's assume I have an area of 1 and a thickness of 1 and I am using the default 1,000 for my Mass Density.

How much does that weigh?
I think I still need to know what is the unit of Mass Density. If it is Kg then my 1x1 grid weight 2,200 pounds. Does that seem right?

Attachments:
Untitled-1.jpg (54.8 KB)

Using Houdini Indie 20.0
Windows 11 64GB Ryzen 16 core.
nVidia 3050RTX 8BG RAM.
 Report
User Avatar
symek
Member
1390 posts
Joined: 7月 2005
Offline
 
Enivob
Using the equation let's assume I have an area of 1 and a thickness of 1 and I am using the default 1,000 for my Mass Density.
How much does that weigh?

1000kg == 1m2*1m*1000kg/m3
I think I still need to know what is the unit of Mass Density. If it is Kg then my 1x1 grid weight 2,200 pounds. Does that seem right?
Unit of mass density is not kg, but kg per volume, like unit of speed is distance per time interval.

Density unit is mass/volume, so in Houdini it is kg/m3.
Edited by symek - 2017年10月13日 11:06:51
 Report
User Avatar
tamte
Member
8839 posts
Joined: 7月 2007
Offline
 
additionally you can look at the units tag in the Type Properties or Edit Parameter Interface windows when you select certain parameter
Edited by tamte - 2017年10月13日 11:13:16
Tomas Slancik
FX Supervisor
Method Studios, NY
 Report
User Avatar
Enivob
Member
2631 posts
Joined: 6月 2008
Offline
 
Ok, the math still does not make sense to me.

How about this…

How much does a 1x1 default grid weigh if I turn it into cloth with a density of 1000?
Using Houdini Indie 20.0
Windows 11 64GB Ryzen 16 core.
nVidia 3050RTX 8BG RAM.
 Report
User Avatar
symek
Member
1390 posts
Joined: 7月 2005
Offline
 
Enivob
How much does a 1x1 default grid weigh if I turn it into cloth with a density of 1000?

With default thickness (0.001m) its wight will be 1kg.

1m2*0.001m*1000kg/m3 = 1kg
 Report
User Avatar
Enivob
Member
2631 posts
Joined: 6月 2008
Offline
 
So that is 2.2 pounds.

When you write a series of symbols on the screen like 1m2 what does that mean in coding language? Is that one times the variable m to the second power?

I don't understand math symbols but I do understand code.
how do I convert “1m2*0.001m*1000kg/m3 = 1kg” to a function?
float result = 1 * m^2 * cloth_thickness * cloth_density / (m^3);
Is that right?
Using Houdini Indie 20.0
Windows 11 64GB Ryzen 16 core.
nVidia 3050RTX 8BG RAM.
 Report
User Avatar
BabaJ
Member
2129 posts
Joined: 9月 2015
Offline
 
The series of ‘symbols’ is so that one know what the parts of the equation stand for.

So expressed in code:

float      size = 1;   // 1m2 or 1x1
float thickness = .001 // .001m
float density   = 1000 // 1000kg/m3

float result    = size * thickness * density; // result represents kg because of the units used in the formula
                                              //ie. m2, m and kg/m3
 Report
  • Quick Links