Find out CENTER OF GRAVITY of a odd shaped 2d area

[wimal]

cad version 2009 ,can anybody help

[Tharwat]

cad version 2009 ,can anybody help

 

Is it closed ?

Can you post image or a dwg of that shape ?

 

Tharwat

[MSasu]

Use REGION command to transform the said shape into a region entity and after apply the MASSPROP command on it – along other features will return the center of gravity too. The region entity support also boolean operation – that it, if case, you can create holes in that shape (SUBTRACT) or define it from two or more parts that are not in touch (UNION).

As Tharwat observed, the center of gravity have no meaning for a contour with gaps.

[wimal]

yes it is closed

SAMPLE2.dwg

[MSasu]

Just use the solution I suggested above - it will give you the desired information (listed as X and Y coordinates in current UCS under Centroid criteria).

Out of curiosity, what units do you use? The size of that shape is huge (167794 x 105499) in drawing units.

[Tharwat]

yes it is closed

 

Check the property of the object and it is not closed .

 

Select shape and press Ctrl+1

[wimal]

Thanks everybody . It works.

[Dadgad]

Good call Mircea, it seems that lots of users overlook the MASSPROPERTIES functionality.

The units are inches.

Based on the ASSUMPTION that it is drawn full size in modelspace, as it should be.

I drew a line of 1500 units and put an architectural dimension on it and it gave me 125'.

1500/125=12

[MSasu]

Check the property of the object and it is not closed

This in not mandatory; as long the ends of that contour are in contact, the entity will be accepted by REGION command.

[Dadgad]

yes it is closed

Tharwat is absolutely 100% correct.

It appears to be closed, but is not, and yet Mircea's region technique is unaffected by that.

All's well that ends well.

[Tharwat]

Here is my code but on closed Polylines only .

 

(defun c:Test (/ spc s)
 ;;; Tharwat 25. July. 2012 ;;;
 (vl-load-com)
 (if (not acdoc)
   (setq acdoc (vla-get-activedocument (vlax-get-acad-object)))
 )
 (setq    spc (if    (> (vla-get-activespace acdoc) 0)
         (vla-get-modelspace acdoc)
         (vla-get-paperspace acdoc)
       )
 )
 (while (setq s (ssget "_+.:S" '((0 . "LWPOLYLINE") (-4 . "&=") (70 . 1))))
   (progn (setq cn
         (vlax-get (setq
                 r    (car (vlax-invoke
                      spc
                      'addregion
                      (list (vlax-ename->vla-object (ssname s 0)))
                    )
               )
               )
               'centroid
         )
      )
      (print cn)
      (vla-delete r)
   )
 )
 (princ)
)

[Tharwat]

@ Dadgad

 

You have written my name wrongly

[Dadgad]

Tharwat, I am very sorry, I am typing on my dell and I get lots of double entries.

When I first posted that I noticed that there was an extra 't' at the end of your name, went right back in to fix it......

Didn't do a very good job of that, sorry!

[Tharwat]

Tharwat, I am very sorry, I am typing on my dell and I get lots of double entries.

When I first posted that I noticed that there was an extra 't' at the end of your name, went right back in to fix it......

Didn't do a very good job of that, sorry!

 

It's Ok

 

Cheers

[amarcon]

Here is a solution I stumbled across a while ago. This was *free* so I hope the author doesn't mind me sharing (could not find the old link). To test, simply drag/drop attached 'Centroid.vlx' (within attached ZIP archive) on your drawing and type CENTROID. Select Polyline, Region or 3D Solid. I use it to check my other routines when I have complex 3D solids, however, just as useful in the 2D world as well. Hint just adjust PDMODE = 66 to see centroid clearer.

Centroid.zip