Measuring data for a moving object often requires the use of specialized measurement devices which may be costly, complex and time-consuming to install. Dartfish offers a set of drawing tools that allow measurements to made quickly from video images
This lesson shows you how to use the angle, distance and timer tools.
Your questions answered
Can I record these measurements using Dartfish?
Yes. The data table drawing tool can be linked to any drawing and used to record its position. These coordinates can be used to calculate distances and speeds. In the specific case of he measurement tools, the data table can record the measurements made by angle and distance tools. The data table records time so there is no need to have a specific action related to the timer tool.
Has the accuracy of the measurements been independently verified?
No. If accuracy is important, and particularly if measurements are being used for research, you must verify the accuracy and establish error margins. There are too many variables to be able to give a single answer for everyone. Although Dartfish does not distort the images it receives from the camcorder, any light passing through a lens suffers from a degree of distortion. The image quality will affect how easily you can identify the positions being measured. Dartfish can only make measurements in two dimensions, therefore objects being measured should remain square on to the camera and the camera placed at a distance to the object to avoid the effects of parallax.