SightLine Applications Command, Control, and Script API  v3.5
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SLATrackingPositions_t Struct Reference


Periodic report of all tracked positions.

typedef struct {
u8 cameraIndex;
u8 numTracks;
struct {
u8 index;
s16 col;
s16 row;
s16 wide;
s16 high;
s16 velCol8;
s16 velRow8;
u8 confidence;
u8 flags;
} track[127];
u64 timeStamp;
u32 frameId;

Tracking and scene confidence scores indicates the system's confidence between 0 (low) and 100 (high). Tracking positions are in camera (unstabilized) coordinates. Enable with SLACoordinateReportingMode_t. For reporting telemetry to multiple destinations see SLASetTelemetryDestination_t.

Rendering Track Points

In order to render the tracking point of interest in display coordinates, with (0, 0) being the top left pixel, use the following equation :


where (xt, yt) are reported tracking coordinates, (xc, yc) are the coordinates of the center pixel of the frame, (xd, yd) are reported display offsets, (Zd) is the optional digital zoom factor, available in SLACurrentDisplayParameters_t, and A is the reported screen rotation. This information is contained in the SLATrackingPosition_t packet.

Primary Track

NOTE: In tracker only configuration only row, col, high, wide, confidence, and flags are populated with valid data, and only for one track.
NOTE: Telemetry output is not available in Demo Mode.

Message ID 0x51

Byte Offset Name Description
4cameraIndexCamera Index
5numTracksBits 0..6: number of tracks (up to 110 reported), Bit 7 indicates MTI tracks are present
variesindexTrack index N: 0-9 = Object tracker or Vehicle/Person/Drone detection; 10-109 = All other detection modes
variescolTracking column in camera coordinates
variesrowTracking row in camera coordinates
varieswideTrack width
varieshighTrack height
variesvelCol8Track horizontal velocity multiplied by 256 in pixels/frame – positive is to the right (only valid for Vehicle and Person Mode tracks)
variesvelRow8Track vertical velocity multiplied by 256 in pixels/frame – positive is down (only valid for Vehicle and Person Mode tracks)
variesconfidenceTrack Confidence (0-100) Bit 7 high indicates coasting of target (obstructed or out of FOV). It is important to use bit 7 to determine if the target is in a coasting state because the confidence at which a track enters the coasting state may vary based on the tracking mode.
variesflagsTrack flags
Bit Description
0 1 = Primary track, 0 = Not primary
1 1 = Selected track
2-3 0 = Track Off, 1 = Track Below Threshold, 2 = Track Off Screen, 3 = Track Active
4-6 Reserved
7 1 = Coast mode on (freeze model update, freeze search and update, or freeze propagation), 0 = Coast mode off. Controlled via SLAModifyTrackIndex_t
variestimeStampTimestamp, if auxiliary telemetry is enabled – see SLACoordinateReportingMode_t
variesframeIdFrame ID, if auxiliary telemetry is enabled – see SLACoordinateReportingMode_t