Tracking motion using optical flow

In this recipe we will learn how to track motion in the images produced from a webcam using OpenCV using the popular Lucas Kanade optical flow algorithm.

Getting ready

We will need to use OpenCV in this recipe, so please refer to the Integrating with OpenCV recipe from Chapter 3, Using Image Processing Techniques and add OpenCV and it's CinderBlock to your project. Include the following files to your source file:

#include "cinder/Capture.h"
#include "cinder/gl/Texture.h"
#include "CinderOpenCV.h"

Add the following using statements:

using namespace ci;
using namespace ci::app;
using namespace std;

How to do it…

We will read frames from the camera and track motion.

1. Declare the ci::gl::Texture and ci::Capture objects to display and capture from a camera. Also, declare a cv::Mat object as the previous frame, two std::vector<cv::Point2f> objects to store the current and previous features, and a std::vector<uint8_t> object to store the status of each feature...