Triangulate denser parts of contour

I am trying contourf(data) to plot the graph and I want to somehow enclose the more denser (or lighter) parts in some shapes like triangulate them. Please let me know if I can use some already available function or something that could help me achieve this. I have the contour image which I am posting here and the red triangles I have made with hand is something I am looking for. Thank you very much for the help.