IOU and KLT tracking

Whats the difference between IOU and KLT tracking in machine vision?

IOU (Intersection Over Union) is an evaluation metric used to measure the accuracy of an object detection model. The metric calculates the ratio of the area of intersection (overlap) between the predicted bounding box and the ground truth bounding box and the area of the union of the two boxes. KLT (Kanade–Lucas–Tomasi) tracking is an algorithm used to track the motion of objects in videos. It is based on an iterative process of finding the maximum correlation between the feature points of an object in two successive frames. It is used to track the position of an object between the frames, enabling the user to determine the velocity and acceleration of the object.

IOU working method:

1. The object to be detected is first identified using a feature detector such as a Haar cascade classifier.
2. The detected object is then represented by a bounding box that encircles the object.
3. The intersection over union (IOU) metric is then calculated by dividing the area of overlap between the predicted bounding box and the ground truth bounding box by the area of the union of the two boxes.
4. The IOU value is then used to evaluate the accuracy of the object detection model. If the IOU value is close to 1, then it indicates that the model is highly accurate; if the IOU value is close to 0, then it indicates that the model is inaccurate.

KLT working method:

1. Calculate the intensity gradients of the image.
2. Find the feature points in the image by looking for local maxima in the gradient magnitude.
3. Create a feature tracking window (also known as a search window) around each feature point.
4. Calculate the sum of the squared differences (SSD) between the feature points of the current frame and the search window of the previous frame.
5. Calculate the correlation coefficient (CC) between the feature points of the current frame and the search window of the previous frame.
6. Select the feature point with the highest CC.
7. Update the search window location to the location of the selected feature point and repeat steps 4–7 until all feature points are tracked.

The accuracy of either metric depends on the application. IOU is more suitable for evaluating the accuracy of object detection models, while KLT tracking is more suitable for tracking motion in videos.

KLT tracking is based on an iterative process of finding the maximum correlation between the feature points of an object in two successive frames. This allows it to track the position of an object between frames more accurately than IOU, which only measures the overlap between two bounding boxes.

Visioline has tested both, in real life, CPU and GPU usage is approximately the same.