Hi, I am trying to find the surface area of a figure and as the title suggests and am unable to do so. I have tried a couple ways (a double integration of the surface normals by calling the trapz function within a trapz function) and taking the cross product to find the area of the individual triangles and then adding the areas up. I keep running into errors though and was hoping I could find help here. I think my problems lie in a misunderstanding of the triangle indices data I have and how to use them to find the surface area.
I have 3 matrices, vertices(mx3), triangles((~2*m)x3), and normals(mx3). My understanding is that the columns of vertices are the x, y, and z coordinates respectively, the columns of normals are the x, y, and z coordinates of each vector for each point in vertices, and then triangles is what I am a little confused about. I think it is the indices of the coordinate points in vertices, but am not sure. Could someone shed some light on what it probably is, and if I am right, give an explanation so that I may understand it better?
Further, if you could provide a push in the right direction to getting the surface area, I would greatly appreciate it!
x = linspace(floor(min(conc(:,1))),ceil(max(conc(:,1))));
y = linspace(floor(min(conc(:,2))),ceil(max(conc(:,2))));
S = sqrt(normals(:,1).^2 + normals(:,2).^2 + normals(:,3).^2)./normals(:,3)
SA = trapz(y,trapz(x,S));
where conc is the concatenated matrix of the matrices of vertices (there is more than one vertices matrix, but I just concatenate them vertically), and normals is the vertically concatenated matrices of surface normals.
This leads to the error "Error using trapz (line 58) LENGTH(X) must equal the length of Y in dim 1."
Thanks in advance for any help and insight!
