Two problems with tracking motile cells

Hi all,

I have two problems when I’m tracking migrating cells:
1: new objects are not assigned a unique identifier. According to the manual, when using the TrackObjects module, “Label: Each tracked object is assigned a unique identifier (label). Results of splits or merges are seen as new objects and assigned a new label”.
When I have splits, the cells are given the same label. Is it possible to get unique identifiers? This would make the tracking a lot easier.
2: when I’m analyzing migrating cells, the output values for ‘DistanceTraveled’ are increasing linearly over time. The manual states “The distance traveled by the object from the previous frame to the current frame (calculated as the magnitude of the distance traveled vector).” , however when I compare the actual X-Y position of any object in two frames it does not correspond to the DistanceTraveled. As example, the shift in position based on XY-coordinates is around 8 to 10 pixels between frames, but DistanceTraveled returns values of 100 and higher. Do you have any idea what’s happening?

I’m looking forward to understanding the problems,
Thanks in advance,

Michiel

ps. if needed, I can attach some images of tracking results with output values.

At this point, no (and we apologize for the misleading help entry). However, we have this issue listed as a recommended feature for a future release.

It turns out that DistanceTraveled is calculating the wrong thing, at least from what is described in the help :astonished:. What’s being calculated as DistanceTraveled is the point-to-point distance from the initial (x,y) position of the object to its current (x,y) location, and not the frame-to-frame distance as the help describes. We will make a point of correcting this in the help text for the next release.

In the meantime, you can calculate the frame-to-frame distance moved as the square-root of the squared sum of the TrajectoryX and TrajectoryY measures. You can do this using the CalculateMath module or offline in Excel with the final table of figures.

Thanks!
-Mark