Use Norfair with a bbox obtained with selectROI from OpenCV about norfair

[moooises]

Hi @facundo-lezama, thanks for the quick response.

I'm interested in having both application, tracking with an object dectector and with a box made by hand.
I'm planning to deploy them in a camera with motion sensor and it want to see how to make the camera moves following a tracked object. Because I have been working using Norfair for the past month, I was trying to make it work using Norfair too.
But it is ok, I will just use an OpenCV tracker for this case.

Thank you so much.

[facundo-lezama]

Hi @moooises, thanks for the detailed explanation.

Norfair is designed to be what is called a tracker by detection, meaning that it expects to have detections to be able to track objects. The motion estimation is done by a Kalman Filter that expects detection evidence to estimate new positions for the objects. There's no visual information included in the estimation, so it isn't possible to estimate future positions based on a single detection (the first one defined by hand), it is necessary to give a couple of detections so the positions and velocities can be estimated. This being said, even if you feed the Tracker with a couple of detections at first, it isn't possible to estimate the positions of the objects through the rest of the video because Norfair's Tracker expects to be fed detections at least once in a while.

Norfair is designed to allow some frame skipping in case the user needs some extra speed, and it also allows for some missing detections, but it heavily relies on having detections to track objects.

Can you mention a bit more about the use case? Why do you need to select the object yourself?

[facundo-lezama]

Let us know how it goes! Maybe this is something we can discuss internally and see if it fits what we want for Norfair.