Video Analysis¶
The lecturesight-videoanalysis-templ bundle performs template-based
video analysis and provides the ObjectTracker service.
The tracker will follow a maximum of 6 targets, using template-matching between frames to maintain persistence. New targets are identified when cells in the overview image exceed defined change thresholds. Targets are dropped when they are inactive for a defined period.
The tracker provides the list of active targets to the Camera Operator which is responsible for selecting one or more targets to follow. The Object Tracker display shows the targets being tracked.
Configuration¶
| Key | Default | Description |
|---|---|---|
| cv.lecturesight.videoanalysis. change.threshold | 48 | Pixel color change threshold. A pixel has changed if the summed difference in all color channels of the pixel in two consecutive frames exceeds this value. |
| cv.lecturesight.videoanalysis. cell.activation.threshold | 3 | Threshold for when a cell is activated. If there are more than this number of changed pixels in a cell, the cell is activated. A cell is 8x8 pixels. |
| cv.lecturesight.videoanalysis. object.cells.min | 2 | Minimum number of active cells in a cluster to be considered a tracking target. |
| cv.lecturesight.videoanalysis. object.cells.max | 128 | Maximum number of cells that a tracking target may consist of. |
| cv.lecturesight.videoanalysis. object.match.threshold | 15 | Template match score must exceed this value for the object at the template location to be considered the same object between successive frames. |
| cv.lecturesight.videoanalysis. object.move.threshold | 3 | Movement threshold: the target is considered to have moved between two successive frames if the distance between positions exceeds this value. |
| cv.lecturesight.videoanalysis. object.dormant.min | 400 | Minimum time in ms that a tracking target may be dormant before it is discarded from the list of targets. |
| cv.lecturesight.videoanalysis. object.dormant.max | 8000 | Maximum time in ms that a static tracking target may be dormant before it is discarded from the list of targets. |
| cv.lecturesight.videoanalysis. object.dormant.age.factor | 0.5 | Scaling factor that increases the dormant timeout value as the object ages. Older objects have a higher timeout value. |
| cv.lecturesight.videoanalysis. object.active.min | 500 | Minimum time in ms that a tracking target must be active before it is included in the target list provided to the camera operator. |
| cv.lecturesight.videoanalysis. object.timeout | 60000 | Maximum timeout in ms for target. This timeout is applied when the target has moved at least a certain distance from its original position. |
Template-Matching Video Analysis uses the ConnectedComponents service, which has the following configuration options:
| Key | Default | Description |
|---|---|---|
| cv.lecturesight.blobfinder.bl obs.max | 100 | The maximum number of blobs that an instance of a BlobFinder can work with. This value affects the size fo several GPU buffers. Thus this may help to solve memory shortages on older GPUs. |
| cv.lecturesight.blobfinder.bl obsize.min | 20 | Default minimum size (in pixels) of a valid blob. This value is usually set by the consumer when instantiating a BlobFinder. |
| cv.lecturesight.blobfinder.bl obsize.max | 10000 | Default maximum size (in pixels) of a valid blob. This value is usually set by the consumer when instantiating a BlobFinder. |
Commands¶
| Command | Description |
|---|---|
| va:reset | Clears the target list and resets the tracker. |