How to determine an estimate of speed and overall distance travelled

molly mactaggart
2 Posts

Hi All,

I apologise in advance, I am very new to this software and am not techy at all, I am sure this is very easy!

I have a video of a maggot moving. I have made a track using point mass and manually tracked its movement through around 20 frames. I have used a calibration stick of 1cm.

As I am sure you can imagine this maggot is not moving in a straight line, basically wiggling from side to side.

Firstly I would like to calculate the overall distance travelled by the maggot. Surely this is possible by adding all of the distances between the points I made. Then the distance would be unitless, but as I used a callibration of 1cm, the programme could then compare to the calibration stick to give me an answer in cm?

Secondly I would like to calculate the average speed travelled by the maggot. Again, surely this is possible using a similar method as before.

I am sure this is very simple to do, and I am being incompetent by not finding this out myself. Again, I am very bad with technology! Thank you in advance for your help and patience.

I would really appreciate some help as soon as possible, as I am finding this all rather stressful and overwhelming!

Re: How to determine an estimate of speed and overall distance travelled -

Douglas Brown
339 Posts

Hi Molly,

For total distance traveled, you could use the method you describe, and yes, the calibration in cm means the total distance you determine will be in cm. Another way would be to look at the speed (velocity magnitude) data in the Data Tool (first show the v vs t plot in Tracker, then right-click and choose Analyze to open the data in Data Tool). In Data Tool, click the Measure button and check the Area checkbox. The area under the curve is the total distance. However, this will NOT include the first or last posiition so it will be a little smaller than your method. In Data Tool, you can also click the Analyze button and check the Statistic box to see statistics, which includes the mean value. So you can get the average speed this way.