Centre of Gravity (C of G)

[dchope]

Within the oil and gas industry there is a requirement to determine the center of gravity of both elements & groups of elements. A beam on its own would be easy to calculate but how would you work of the c of g on say some living quaters needed to be craned into location. Does ANYONE know of any add-ins to Revit that can help calculate this?

Regards

[damon.sidel]

Sounds pretty interesting. I don't know of any add-in that does this already, but the people at CASE Inc. do this kind of custom add-in and would be able to help you (for a fee, of course). It seems pretty intriguing, requiring knowing the mass and calculating the centroid of each piece of your object. I could write the script in Rhino, but that would require translating the model and data between Revit and Rhino. I think your best bet is hiring a developer like CASE Inc. to write you a custom add-in. It would be a cool one.

[MikeJarosz]

I had to calculate the COG of a 2D polygon in Acad once. The formula was to find the min and max x coordinates and take the average, then do the same for Y. (Avg X) and (Avg Y) is the COG. I imagine for a 3D object the same applies to the z-extents.

[damon.sidel]

Here's a paper on the subject... more info than necessary, but I love math so I couldn't help but dredge up some old memories:
http://ruina.tam.cornell.edu/Book/COMRuinaPratap.pdf

[MikeJarosz]

You would have had fun with Acad's light polygons. They were heavier than lead. The x and y coords were cartesian, but the z was a vector. What a nightmare. I had to learn dot products and cross products. Someone from New Zealand whose name I have forgotten bailed me out on that one. The polygon had to be transformed to be perpendicular to my nose, or something like that, before I could manipulate it.