# How to measure surface area in mm^ generated using triangulaiton of a 3D object model by Matlab

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M.S. Khan on 24 Aug 2020
Edited: Bruno Luong on 26 Aug 2020
I have geneated Cone Model. The cone was generated using radius 78 mm and height 188.4 mm. Using trimesh(), i have triangulated it to measured its suface area. Please help me how to measusre caliberation factor to approxite it surface area or volume. i will be very thankfull for your cooperation and guidance.
Attached are coordinates and the figure of the cone. Thanks for the guidance of KSSV and Uday.
Regards,
bx = Boundary(:,1) ; by = Boundary(:,2) ; bz = Boundary(:,3) ;
T = delaunay(bx, by)
TO = triangulation(T, bx(:),by(:),bz(:));
area = 0;
for i = 1:size(TO.ConnectivityList,1) %the number of rows gives the number of triangles produced
a = TO.Points(TO.ConnectivityList(i,:),:); %this gives the 3 vertices of the ith triangle
if any(a(:,3) > max(bz))
continue;
end
%extract the three vertices
p1 = a(1,:);
p2 = a(2,:);
p3 = a(3,:);
format compact
area = area + 0.5 * norm(cross(p2-p1,p3-p1)); %calculate the area of the small triangle and add with previous result
end
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The above code gives me surface area = 47975.3181943477. This represent pixel, right.
How to measure the real surface area by applying caliberation factor. Please help me how to measure caliberation factor because i am new in this field.
The cone is orginally genereated having radius 78 mm and height 188.4 mm.
Bruno Luong on 26 Aug 2020
Edited: Bruno Luong on 26 Aug 2020
No. This is the correct formula
V = 1/3 * pi * r^2*h
anything different than that is not.