Frequently Asked Questions

Tracking - Answers

Is there an automatic tracking?
Yes, in Simi Motion or Simi MotionCapture 3D, not so in Simi MoStill or Simi TwinnerPro.

How is tracking done?
With SIMI°Motion or SIMI°MotionCapture you can use colored, black and white or reflective markers. Once you have identified the marker, the system tracks the points automatically as long as they are visible. If they are hidden, the system stops and you can estimate where they are and click manually or you leave the frames out until they are visible again. Then you have to identify them again and let the system track them automatically again. With special marker sets you can calculate joint centers, moments and forces. In a 3D view (skeletal, stick or other models) you can trace single points and superimpose them. You also can trace joint centers or centers of gravity of single segments.

How many markers can I use?
You may us up to 200 markers.

What size are the markers?
The size can be as small as < 1mm and - depending on the distance of the cameras to the object - as big as you want. The system tracks pixels. The minimum pixel requirement for tracking is 16 pixels (area of 4x4 pixels).

What type of markers can be used with the SIMI Products?
Users may choose between reflective or non-reflective markers, white or colored markers. Colored markers are good when capturing a small area and markers are close together.

Does your system require active markers?
No, all markers are passive.

Do I have to wear a special suit?
No.

How are the markers attached to the body?
The markers may be easily attached using double sided tape or may be fixed to a bodysuit.

How good must the contrast between the markers and the background be for automatic tracking? How is automatic tracking done? Is it via centroids or iterative prediction?
The human eye can not always detect good contrast between the markers, but the software does because it looks through a number of color spaces to detect the shape of the marker. The most important thing is to have clear information of the shape of the marker. If the color of the marker merges with the background color, you may have a problem. The algorithm is a dynamic algorithm, which means that the marker template is updated and adjusted frame by frame.

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