Trouble triangulating a surface

I have attached a text file with the data I am discussing.

I need to triangulate this data so that I can write the triangulation to an stl file using stlwrite (from the file exchange). The problem is that this sequence produces triangles that are NOT in the plane for seemingly no reason. As can be seen, all of the points are in a circle. How can I triangulate this surface without the wierd out of plane triangles appearing??

>> D = importdata('Endcap.txt');

>> TRI = delaunay(D(:,1),D(:,2),D(:,3));

>> trisurf(TRI,D(:,1),D(:,2),D(:,3))

>> hold on

>> plot3(D(:,1),D(:,2),D(:,3),'*r')

Note that I expected something like this:

>> surf([D(:,1),repmat(mean(D(:,1)),length(D),1)],[D(:,2),repmat(mean(D(:,2)),length(D),1)],[D(:,3),repmat(mean(D(:,3)),length(D),1)])

[darova]

try alphaShape for triangulating

[David Winthrop]

Thank you but this didn't do the trick.

For example:

>> Du = unique(D,'rows');

>> TRI = alphaShape(Du(:,1),Du(:,2),Du(:,3));

>> trisurf(TRI.Points,Du(:,1),Du(:,2),Du(:,3))

Error using patch

Value must be of numeric type and greater than 1

Error in trisurf (line 91)

h = patch('faces',trids,'vertices',[x(:) y(:) z(:)],'facevertexcdata',c(:),...

[darova]

I don't have alphaShape

Try

plot(TRI)

see HELP