How to make united polygons from separated polygons?

I have 3 separated polygons of each variables (Polygon#1, Polygon#2,Polygon#3).

I would like to make one united polygon from 3 separated polygons as the picture.

I tried with union funtion of matlab, but it works only for contacted Polygon.

Please give me some helps or hints...

Answer 1

[KSSV]

Let P1,P2,P3 be your three polygons data which I am assuming as column dominant.

P = [P1; P2; P3] ; % merge the data
idx = boundary(P(:,1),P(:,2)) ; 
P = P(idx,:) ; 
plot(P(:,1),P(:,2))

The above shall work if not share the data.