Recording position and speed


dat_position

Linking a Data Table to any drawing object is done in the same way as linking an angle drawing.  However when you are specifically interested in positional information it is important to calibrate the image first.

If the position of an object is being tracked using automatic tracking or by using a spline then data can be automatically added to the data table at a fixed interval.

swf_icon_1_small Calibrating and measuring distances

swf_icon_1_small Data Tables - automatically recording distance & speed

swf_icon_1_small Setting an origin for a Data Table

 

Update

Since this tutorial was created it has become possible to set an origin in a new way: right click a marker cross and select Set as origin from the quick menu.

 

Your questions answered

I don't want to know the distance from an origin, I want to know how far my tracked object moves between each sample.  Can a Data Table show this?

Yes.  Record positional data as shown in the animations then add an Interval Length column to your data table.

Can distance data be added when I choose instead of at a fixed interval.

Yes, these examples automatically added data as the movements of the drawings were tracked but data can be added manually in the same way as the angle drawings were linked in the previous topic.

What units are used for distance and speed?

By default, Dartfish uses meters and meters/second but this can be changed to a range of other decimal and imperial measurement units in the Tools > Options menu.  If the image is not calibrated, then the measurements are shown as pixels.

How do I display the data in the graph?

It is not possible to use the Data Graph or the graph drawing tool to display data table data. These features are only used to display imported or linked data as discussed elsewhere in this tutorial.
However, you can export the data to a spreadsheet and graph it there.