Delete triangulations outside the outline polygon and z value manipulation

I have an outline polygon traced using impoly, over an image of an outline. When I triangulate it using delaunay command, triangulations extend outside the polygon. how to delete these unwanted triangles, and then manipulate the z values of the polygon, to change its orientation? I'm using Matlab R2008a

Answer 1

[Paul Rötzer]

I know the answer comes very late but i struggled with the same problem today.

For newer version of matlab the following should work:

% P contains the points on outline of polyshape 
polyin = polyshape(P);
EdgeConstraint = [(1:length(P))' [(2:length(P))'; 1]];
DT = delaunayTriangulation(P, EdgeConstraint)

%% remove outside triangles
C = incenter(DT);
TF = isinterior(polyin, C);
InsideTriangles = DT.ConnectivityList(TF, :);

[Yonni f]

Amazing. I was just strugging on the same thing and I found your response to a decade old post.

To ellaborate a bit more on Paul's answer, I edited the triangulation by calling a new structure called dts and then removing the connections outside the border:

dts = struct('Points', DT.Points, 'ConnectivityList', DT.ConnectivityList);

dts.ConnectivityList(~TF, :) = [];

x=triangulation(dts.ConnectivityList, dts.Points);

triplot(x);