Exploring SIFT

SIFT stands for Scale Invariant Feature Transform. It is a patented algorithm that looks for feature points or "interest" points  in an image. These points of interest are independent of image scale, rotation, and illumination and are also quick to compute, making them very robust features.

Each feature point has a scale and orientation. From these images, scale is denoted by the size of the circle, and orientation is denoted by the direction of its radius. Here are some examples of SIFT features detected using OpenCV.

From the images, there are too many cluttered feature points, so it might be best to choose the most important ones, and leave out others. Next time I will try to use these SIFT features to detect bilateral symmetry, and other key features.