calculate surface area from xy coordinates (R2017a)

hello, so I have this x y coordinates of a foot from 3d scanning (graphical form as shown in the picture), can I use matlab to calculate the surface area based on the division of the area like this (ex: midfoot, heel)? or should i divide the area first and then calculate the area later? thank you in advance

Answer 1

[KSSV]

Let (x,y) be your coordinates....

idx = boundary(x,y) ; 
bx = x(idx) ; by = y(idx) ;
A = polyarea(bx,by) ;