Where is the center of gravity?

FenS

Hi all,

i´ve got one more sculptural problem with which you might be able to help...
A while ago i created some sculpture just by drawing a cube, drawing some lines and erasing some parts.
Finally i made this sculpture out of stone but then the problem became that it would fall backwards so i had to remove some stone in the back to make it more stable.
(an option is ofcourse to glue it to some plate or something, but i wanted it to be a single statue, without pedestal (google translate? a block of stone beneath it)
(if i am not mistaken, the statues will fall if the center of gravity is outside the base it is standing on, so here is my question:
i am trying to create future statues with the help of SU and this is typically one of those statues but would i be able to tell if it would fall or not?

Here is a (not so clear) picture of the statue (really balancing right now),
i will also insert the skp that i made today,
scene 5 is a little bit like i meant to make the sculpture (with the Rhino-nose not that straight though), but when i made it like this, it was falling backwards, so i had to remove the top and some stone in the back of the statue and it is still balancing)

beeld99.skp

pilou

Maybe some tricks can be made with Sketchyphysics3 by CPhillips
(made here with the Sketchyphysics2)
Put your object over the special plan, then launch it
You will see how it will be on the ground
(click on the image if scrollbars)

alexschreyer

Another approach: You can get the main cross-sections using the slicer plugin and then find the centroids of those faces using my centroid plugin (search index for both). That will give you an approximation until someone writes some volume centroid code.

FenS

Hi Pilou and Alex,

thanks for your replies!
I think i will give sketchyphysics a try,
heard a lot about it, never tried it, maybe it is time now

Thanks again!

Gaieus

I don't know how useful in this case CenterPoint.rb would be but as I imagine, when you have created your statue and set the center point for the whole structure, in theory a vertical line drawn to the ground plane from it would show if the center of gravity lies inside or outside the "base" of the statue.

alexschreyer

Hi All,

Sketchyphysics and centerpoint work well for convex or cubic volumes, respectively. For example, centerpoint will use the center of the bounding box. Both approaches will not give you the true centroid in your case, which you need to figure out the center of gravity (assuming you have a homogenous material). You can only do that with my plugin but only for 2d shapes.

If you need a better evaluation of the volume centroid, then look at a software like Rhino.

Cheers, Alex