Boundary command

[PGia]

Hi
I’ve run into this problem several times, but I was never able to understand why — until today.
Sometimes I need to use the "boundary" command to obtain the perimeter of complex enclosed areas, but occasionally the area of the region returned by the command does not match the expected value.
Today, I finally discovered why.

In the image, I show an example of this. The thick yellow line is part of the original geometry, while the thinner dark-colored line is the one returned by "boundary".
I repeated the command several times, but it always makes the same mistake.
Does anyone understand why this happens?
Is it possible to solve it somehow?

Thanks in advance.

[BIGAL]

No idea what the thick yellow line is ?

 

If its a pline with a width then boundary is correct, it does not recognise pline thickness. I am sure there is ways to make a outline of the plines can then run boundary.

 

If it's a hatch then can get outlines of hatch's then should be able to do a boundary.

[hmspe]

https://lee-mac.com/polyoutline.html  or  https://lee-mac.com/advpolyoutline.html  will outline a pline.  https://jtbworld.com/autocad-hatchb-lsp

 willoutline a hatch.  I can't tell what might be required to automate the process without a DWG of a full pline set or hatch set example.

[PGia]

I think I didn’t explain myself properly.

The idea is to run "boundary" and click inside the largest closed area shown in the image.

After checking the result — by zooming into the area indicated by the arrow — you’ll understand what the image in my previous message is referring to.
I’ll attach a drawing.

Boundary.dwg