# Finding the center of multiple surfaces

Hi,

I am building a structure made with sheets. The structure is made of several irregular surfaces. I am trying to find the center (average) in order to make a hole and locate an axis that could help me to build the mock up.

I was thinking creating a bounding box for each surface and then find the center for each layer.

Would like to ask you if there is any other way to find the average center for the structure. Kind of an average center of mass which could help me to find the right spot in order to get the placement of the axis through this irregular surfaces.

Find attached the image .

Thanks so much

That’s not a bad idea. AreaCentroid should also work (for planar surfaces). I tried this on Windows.

// Rolf

AreaCentroid does not require planar surfaces. Select a group of surfaces and AreaCentroid will determine the area weighted average centroid for the group.

Actually worked! Did not know that function. Unfortunately I do not have one “center” that all surfaces share…but that is not your concern hahahha thanks a lot

Interesting stuff this. I tested a truncated cone with the largest disk at the bottom. When I calculate the area centroid of the closed polysurface and the volume centroid of the same, the AC sits higher than the VC. Which makes sense.
However, when I explode the polysurface into individual surfaces, the AC and VC of the combined surfaces coincide! So the AC of a polysurface is not the same as the AC of the combined surfaces! Go figure that…

PS. I have been messing up, forget the above.

Do you think for my situation I should use Volume? I am using Areas cause they are surfaces, but thinking it …I am treating them as volume…mmmmm

I am not quite sure what you are after, but if you want to calculate the center of gravity of your combined sheets, it may be best to extrude them to volumes/polysurfaces and calculate the combined volume centroid. At least you will be able to see if it makes a difference to the AC you did already calculate.

Thanks man!

Deleted.
I have been messing things up terribly, sorry for the confusion. Read the PS on my above message. But @Bruno_Suraski: I still believe making your sheets into actual volumes is the surest way to calculate.

Max.