Finding Contours can be useful in creating masks for images and to segment and extract features from an image. Its used by Meteorologists to understand weather maps and for analysis and forecasts. The following post describes how contours could be identified in an image.
Implementation would be based on EmguCV the popular .NET ported version of OpenCV. Even though OpenCV is built in C++, EmguCV provides a wrapper which manages to invoke the same OpenCV libraries.By use of the EmguCV wrapper it provides all the necessary functions as well as data types of OpenCV in a .NET compliant library making it easier to implement.