I have a 3D human face model. Now I'd like to find its boundry when it is projected onto 2D plane. I googled about how to implement it in VTK and find vtkFeatureEdges. However, the result from vtkFeatureEdges is a little confusion to me. It's not only give me the contour of a human face in red color, there are also green curves to draw the outline of nose and mouth. Moreover, the most confusing part is there is a red curve starts from the forehead and stops at the chin which across the face.
Can anyone explain to me how to use vtkFeatureEdges to extract a contour of shape? By that I mean the close curve formed by outermost points.