Compute SIFT keypoint descriptors on a regular grid over the input image. Beware that changing the values for the step and binsize parameters changes the output image size, so you need to adjust your video mappings accordingly. Hence, setting those parameters is best done once and for all in the module's optional params.cfg file. This module can either have a color YUYV output, which shows the original camera image, keypoint locations, and descriptor values; or a greyscale output, which is just the descriptor values.
This algorithm is implemengted using the VLfeat library. It is quite slow, maybe because this library is a bit old and appears to be single-threaded.