Two important things play a role here: in a Data video measurement, every data point is linked to a specific pixel in a specific video frame and using the option Smooth replaces the original measurement data. These two facts conflict, because:
- If the measurement would be interpolated and more data points would be generated, the 1-on-1 connection between a data point and a frame is lost
- The X and Y values of the data points will change by the smoothing operation, which makes the connection to a specific pixel impossible
In short, it is not possible to use the Smooth option.
Note (09/10/2017): from Coach version 7.3 (september 2017) onwards it is possible to do Smoothing in video measurements due to a change in how data processing works.
Alternatively you can smooth your data by using a formula. Click with the right mouse button in the Data table and select Add a New Variable… > in Data Series > Formula. Fill in the formula “Spline(X;Y;-1)” and replace X and Y with the corresponding variable names from the video measurement (default: P1X and P1Y).