TIG's Centerpoint Finder gets confused by triangles

I always believed TIGs “Add Centerpoint” plugin was the go to tool for adding a Center Point and in my tests its appeared to work very well.

But I needed the centre of a star and added a point using the tool and then drew my model around it… But when I reviewed it afterwards its was clearly not the centre.

And this is easy to see if you create a star on the central axis and then add the centerpoint.

As you can see its not in the center at all… So i tried a triangle and was surprised at the results:

When you measure you can see that its not finding the centre, but a point 1/2 way along the red axis.

So then I tried rotating the traingle off axis a bit to see what happens and now I don’t have a clue what its doing… NOw the centre is not an any mathematical centre that I can find:


I guess there is some logic to this, but I can’t work it out… So I just wonder if anyone knows of another ‘Find Center’ plugin which might help?

TIG’s extension simply marks the center of an object’s bounding box. I seem to remember that there once was a center of gravity plugin - you might have better luck with that. The problem becomes the more interesting the more asymmetry the figure has. I don’t think there is a single formula that can determine the geometric center of an arbitrary figure, if there is one.


Illustration of what Anssi described.


If you want to find the ‘Center-of-Gravity’ [Centroid] it is not always the same as the center of the bounding box…
I have CofG extension in the SketchUcation PluginStore…


Here’s a simple plugin I wrote to find the centroid of a face: jimhami42_face_centroid.rbz (817 Bytes)