Tracking objects manually

You can draw trajectories by manually tracking object in the video clip. For example, you could draw the swing plane as illustrated below. The yellow curve represents the up-swing and the orange one, the down-swing. Dartfish creates the trajectory by joining selected points while smoothing the curve in between. The trajectory redraws as the video plays (see image on the right).

To draw a curve, use the Spline tool and proceed as follows:

1.	Right-click on the Line button and select Spline from the context menu.

2.	Position the playhead at the beginning of the performance.

3.	Click on the object you want to track. A white square indicates the first point of the curve.

4.	Use the [ctrl] + left/right arrow keys to move the playhead forward a few frames.

5.	Repeat steps 2 and 3 as many times as needed.

6.	Right-click and select Finish from the context menu to terminate the curve.

To modify the trajectory, select it and move any point you have defined. The curve modifies accordingly.

The trajectory draws as illustrated above only if it is deselected (white squares not visible). To do this, click anywhere in the image but on the curve itself.

The curve can be drawn on a single frame. In this case, no tracking takes place.

The number of points you have to define varies according to the speed of the object. The faster the object, the more points you have to add to get a smooth curve.