Standard Velocity Unit

asked 2018-08-14 02:40:35 -0500

thac00 gravatar image

ello everyone!

I'm currently using this code, to extract clusters from a Point Cloud and track them via a Kalman Filter with constant velocity: GitHub Source

Esentially it's segmenting a pointcloud into clusters of interest, based on euclidean distance. For each cluster it retrieves the cluster center (using PCL).

To associate the clusters between frames consistenly, OpenCV is used, to apply a hungarian algorithm to compare the euclidean distance of the cluster centers and pair them with the minimum distance cost.

A Kalman Filter from the OpenCV library is then applied to track the clusters across a path.

Right now I'm trying to publish the Position and Velocity Values above the segmented Clusters. I'm doing it by using:

KF0.statePost.at<float>(0)
KF0.statePost.at<float>(1)
KF0.statePost.at<float>(2) 
KF0.statePost.at<float>(3)

(for all the Kalman Filters KFi I've initialized, 6 in total)

0 and 1 give me the correct X and Y Position, which I have verified, so 2 and 3 should be the corresponding velocity, however I do not know what the Units are. It cant be m/s because its of the order 10^(-6) and I can't think of any reasonable Unit. Maybe its an angle?
I've read online about pixel/second but that would be a) even more unlikely, because it should be higher than m/s and b) I'm only working with pointclouds and no image, so I'm not sure where I can find a pixel to meter relation.

Screenshot

Thanks in advance and best regards

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