I need the landmark points of a contour
===

I need to detect the source of leakage of a gas. I have numerous images of contours of gas spread from a point source under various atmospheric conditions. The images, i have got using ALOHA software, which gives the contour of gas spread under atmospheric conditions. So, i need the landmark points of the contour with which i can train my neural network to redraw the graph and detect the source of leakage. the prob is in effort to get the landmark point, i might get some wrong coordinate because the contour i have is in the form of image(a graph(a grid)), so the algorithm might get confused in which black line it should consider for image processing. Please help me to get the landmark points of the contour. I wish I could upload an image for better clearance but I think there is no such possibility.Thank You