Finding the center of an irregular shape

[VTwin]

Nice demo. I now understand that the "pole of inaccessibility" is the desired point.

[engkin]

Nice demo. I now understand that the "pole of inaccessibility" is the desired point.

The article posted by Edson in reply #8 is really nice.

Need to work on that Sqrt(MinDisSq) again. Without the ABS around MinDisSq there is a - value that pops in there if you add some points and move it off the screen or around at different places.

I don't think you need to change it. GetSegDistSq returns positive numbers always:

Code: Pascal  [Select][+][-]

1.     Result := round(dx * dx + dy * dy);

Here is a comment from the Javascript file:

// get squared distance from a point to a segment

I believe the error you're seeing is probably a range error from trying to round and fit a double value bigger than MaxInt into an integer variable in the same line:

Code: Pascal  [Select][+][-]

1.     Result := round(dx * dx + dy * dy);

[DomingoGP]

Based on the implementation of jamie and engkin I have reimplemented the routine using floating point variables and a Priorityqueue instead of a list.
I have also implemented the routine to work with BGRABitmap using TPointF.

I have allowed myself to include the license (ISC) just like the original project.

jamie, I have put your data as co-author of the routine (I think they are correct, if not, correct me).
engkin, I can give you credit in the file but I need your real data.

P.S. I have tested it in a real map project and it works fine.

The project now depends on BGRABitmap, but the dependency can be removed by commenting out the definition
  {$ define IMPLEMENT_TPOINTF}

[engkin]

engkin, I can give you credit in the file but I need your real data.

Thank you for your efforts. I did not do anything worth to be credited.

[DomingoGP]

I have used this function in https://github.com/DomingoGP/geopackageViewer and works fine.

but i had to change the test for CellSize because if the polygons are too small i get OutOfMemory error.
const
  MIN_POLYGON_SIZE=10;


  //if CellSize = 0 then      // error out of memory
  //begin
  //  Result.PlotX := MinX;
  //  Result.PlotY := MinY;
  //  Result.Distance := 0;
  //  Exit;
  //end;
  if CellSize < MIN_POLYGON_SIZE then  // poligon to small, return center.
  begin
    Result.PlotX := (MinX+MaxX)/2;
    Result.PlotY := (MinY+MaxY)/2;
    Result.Distance := 0;
    Exit;
  end;