inside and outside region identification from 2D contour A 3D model is sliced against a plane and the resulting 2D contour is projected onto the plane. I am looking for an efficient algorithm to identify the inside and outside region of the contour. Simultaneously I need to identify outer and inner loops within the contours. 

Any references from articles/books is earnestly requested.

Thanks
In general, I recommend the book Real-Time Collision Detection.

For your particular case, my first choice would be to use the 3D test for point-inside-mesh. I assume that the contour is a sequence of 2D segments (a sequence of vertices, essentially) and that the model mesh is "sealed", i.e. there are no holes in its surfaces that would make distinguishing the "inside" and "outside" of it impossible.


Find a bounding box for your mesh.
Cast rays from an edge of the bounding box to the tested point. In your case, the ray would be coplanar with the slicing plane, and the point would be one of the vertices of the contour.
Count how many times the ray crosses mesh triangles.
Odd number of crossings means that the point is on the inside; even number means it's on the outside.
Repeat points 2-4 for all contour vertices.
Classify contour regions by whether their vertices are on the inside or outside.