Technical data

SightLine Applications Command and Control
Positive values of offset indicate shifts down and to the right. In order to render the tracking point of
interest in display coordinates, with (0;0) being the top left pixel, use the following equation:
x = (x
t
- x
d
- x
c
) * cos(A/128) + (y
t
- y
d
- y
c
) * sin(A/128) + x
c
y = (x
t
- x
d
- x
c
) * -sin(A/128) + (y
t
- y
d
- y
c
) * cos(A/128) + y
c
where (x
t
, y
t
) are reported tracking coordinates, (x
c
, y
c
) are the coordinates of the center pixel of the
frame, (x
d
, y
d
) are reported display offsets, and A is the reported screen rotation.
Byte offset Description
2 Packet length = 26 MOD 2.17
3 Packet type = 0x43
4 & 5 Tracking column in camera source coordinates
(signed 16-bit integer)
6 & 7 Tracking row in camera source coordinates
(signed 16-bit integer)
8 & 9 Horizontal scene translation columns in pixels, positive indicates
the scene has moved to the right (equivalent to panning left)
(signed 16-bit integer) Fractional portion is in byte 22. See
below for how to extract scene translation. MOD 2.17
10 & 11 Vertical scene translation rows in pixels, positive indicates the
scene has moved down (equivalent to panning up)
(signed 16-bit integer) Fractional portion is in byte 23. See
below for how to extract scene translation. MOD 2.17
12 & 13 Display column offset
(signed 16-bit integer)
14 & 15 Display row offset
(signed 16-bit integer)
16 Bits 0..6 Tracking confidence (0..100)
Bit 7 Target not visible flag
17 Scene measurement confidence (0..100)
18 & 19 Current display rotation (0..360 degrees) * 128
(unsigned 16-bit integer)
20 Camera Index
21 Frame number (0 to 255), count wraps to 0 when it exceeds 255.
NEW 2.17
22 Horizontal scene translation 8 bit fractional pixel (combine with
bytes 8 & 9). See below for how to extract scene translation.
NEW 2.17
23 Vertical scene translation 8 bit fractional pixel (combine with
Copyright © 2014-2015 SightLine Applications, Inc. Page 71 of 95 Jan 15, 2015