Main Page → Active Marker Tracking
This page provides instructions on how to set up and use the OptiTrack active marker solution.
The OptiTrack Active Tracking solution allows synchronized tracking of active LED markers using an OptiTrack camera system. Consisting of the Base Station and the users choice Active Tags that can be integrated in to any object and/or the "Active Puck" which can act as its own single rigid body.
Connected to the camera system the Base Station emits RF signals to the active markers, allowing precise synchronization between camera exposure and illumination of the LEDs. Each active marker is now uniquely labeled in Motive software, allowing more stable rigid body tracking since active markers will never be mislabeled and unique marker placements are no longer be required for distinguishing multiple rigid bodies.
Sends out radio frequency signals for synchronizing the active markers.
Base Station LEDs
Note: Behavior of the LEDs on the base station is subject to be changed.
This adjusts the complexity of the illumination patterns produced by active markers. In most applications, the default value can be used for quality tracking results. If a high number of rigid bodies are tracked simultaneously, this value can be increased allowing for more combinations of the illumination patterns on each marker. If this value is set too low, duplicate active IDs can be produced, should this error appear increase the value of this setting.
Setting the number of rays required to establish the active ID for each on frame of an active marker cycle. If this value is increased, and active makers become occluded it may take longer for active markers to be reestablished in the Motive view. The majority of applications will not need to alter this setting
The color assigned to this setting will be used to indicate and distinguish active and passive markers seen in the viewer pane of Motive.
For tracking of the active LED markers, the following camera settings may need to be adjusted for best tracking results:
With a BaseStation and Active Markers communicating on the same RF, active markers will be reconstructed and tracked in Motive automatically. From the unique illumination patterns, each active marker gets labeled individually, and a unique marker ID gets assigned to the corresponding reconstruction in Motive. These IDs can be monitored in the Live-reconstruction mode or in the 2D Mode. To check the marker IDs of respective reconstructions, enable the Marker Labels option under the visual aids (), and the IDs of selected markers will be displayed. The marker IDs assigned to active marker reconstructions are unique, and it can be used to point to a specific marker within many reconstructions in the scene.
Rigid body definitions that are created from actively labeled reconstructions will search for specific marker IDs along with the marker placements to track the rigid body. Further explained in the following section.
Duplicate active frame IDs
In recorded 3D data, the labels of the unlabeled active markers will still indicate that it is an active marker. As shown in the image below, there will be Active prefix assigned in addition to the active ID to indicate that it is an active marker. This applies only to individual active markers that are not auto-labeled. Markers that are auto-labeled using a trackable model will be assigned with a respective label.
When a trackable asset (e.g. rigid body) is defined using active markers, it's active ID information gets stored in the asset along with marker positions. When auto-labeling the markers in the space, the trackable asset will additionally search for reconstructions with matching active ID, in addition to the marker arrangements, to auto-label a set of markers. This can add additional guard to the auto-labeler and prevents and mis-labeling errors.
Rigid body definitions created from actively labeled reconstructions will search for respective marker IDs in order to solve the rigid body. This gives a huge benefit because the active markers can be placed in perfectly symmetrical marker arrangements among multiple rigid bodies and not run into labeling swaps. With active markers, only the 3D reconstructions with active IDs stored under the corresponding rigid body definition will contribute to the solve.
If a rigid body was created from actively labeled reconstructions, the corresponding Active ID gets saved under the corresponding rigid body properties. In order for the rigid body to be tracked, the reconstructions with matching marker IDs in addition to matching marker placements must be tracked in the volume. If the active ID is set to 0, it means no particular marker ID is given to the rigid body definition and any reconstructions can contribute to the solve.
› Q : Active markers are flickering from both the 3D viewport in Motive.