Calculate the obstacle velocity

[yanhaochiu]

Hi, tysik! Thanks for providing this obstacle_detector package! It's awesome!

I have a problem about the calculation of velocity. I don't find the place where did you calculate velocity.
The extract node initialize the velocity to 0 and publish it to topic raw_obstacles.
The tracking node subscribe the topic raw_obstacles, and use kalman filter to update the value.
But the custom type TrackedObstacle initialize the velocity by obstacle's velocity which the value should be 0. Can you tell me how did you calculate the velocity?
Thank you very much!!

YanHao,Chiu

[tysik]

Yes, the initial velocity is 0. As the obstacle moves from sample to sample, you get a better estimate because KF settles.

The algorithm first tries to resolve the correspondence between obstacles from previous sample and current sample. If there is no ambiguity about the correspondence between two obstacles, the algorithm simply takes the new position and feeds it into the KF update.

However, if there were two or more obstacles that merged into one, or conversely - one obstacle that split into two or more it is a little bit more complicated since you have to take more factors into account. Please find the .pdf in the docs folder for more information.

[zhengzh]

@tysik Hi, I have a question about the velocity of the circles, when a person walks a straight line, I can see circles track the people very well, but when the person disappear (occluded), the circles just stay there, why don't they move with previous speed before losing the person.