# MATLAB: How to measure surface area layer by layer using Matlab

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i am using following code to find area of layers. I am trying but masking somewhere some mistake. Any help from community will be highly appreciated.
Attached file are the xyz-coordinates. I measure the surface area of one layer using bellow code. This coding is combining all layers. I want to find area of each layer individually. Regards to all for their cooperation and guidance.
``vertices = load(' attached file ')vertices = round(sortrows(vertices,2));Vx = round(vertices(:,1));Vy = round(vertices(:,2));Vz = round(vertices(:,3));G_surface_area =0layer = []surface_area = 0for i = min(Vy):10:max(Vy) % This for loop, i am using to measure by 10 spacing.    minVy =  i        for j = i:i + 9   % This measure is for layer to find its area.                        layer_new = vertices(any(Vy== j,2),:);                  layer = [layer; {layer_new}];        end                             layer = cell2mat(layer)                                   Lx = layer(:,1);                Ly = layer(:,2);                Lz = layer(:,3);                surface_area = polyarea(Lx,Lz)                  G_surface_area = G_surface_area + surface_area            end``

• ``data = importdata("Cone_20000_points.txt") ; data = round(data) ; x = data(:,1) ; y = data(:,2) ; z = data(:,3) ; zi = unique(z) ;   N = length(zi) ; A = zeros(N,1) ; tol = 10^-5 ; for i = 1:N  idx = abs(z-zi(i))<=tol ;   % layer coordinates   xl = x(idx) ; yl = y(idx) ; zl = z(idx) ;   Layer = [x(idx) y(idx) z(idx)] ;   % these are the Layer coordinates   % get boundary of layer   id = boundary(xl,yl) ;   Boundary = [xl(id) yl(id) zl(id)] ;   % Boundary coordinates   A(i) = polyarea(xl(id),yl(id)) ; end``