Our company builds augmented reality mapping systems for a wide variety of FLIR, Wescam, and other gyro-stabilized platforms ( overview video
) As a result, we have a tremendous amount of experience with the systems, and in particular calculating camera position and orientation. We generally receive this data over a serial, ethernet, or HD-SDI (VANC) input, but some variation of the data we use can also be "burned into" the video when video symbology is enabled (as it usually is, and we see in this video).
Every make/model of camera tends to have a unique manner in which they represent turret metadata on-screen -- the symbology in this video is clearly from the Wescam MX line of cameras (they make turrets in a variety of sizes, but the MX-15, having a 15" diameter, is very widely used, and has the same focal lengths seen in the video)
The original MX-15 was Standard Definition only, then evolved to have a High Definition daylight (EOW) camera with a standard definition (640x512) thermal focal plane array that they upscaled by 2 and inserted into the 16:9 aspect ratio HD video frame. In our software, we need to crop out the video so we can replace the border with synthetic imagery. That is the MWIR sensor used in this video.
The EOW camera is a commercial off-the-shelf "block camera" -- while the fields of view vary from camera to camera (we often have to calibrate the FOV and optical center for our customers), it is generally fairly close to the reported values. In addition to the optical zoom, 2 stages of digital zoom are available.
An EOW focal length of 13 = 40.5292 degrees horizontally, and 200 = 2.7494 degrees horizontally. You can see the operator engages the digital doubler (1.5X and 2.0X several times) in the video.
The HFOV we care about in this video is for the MWIR camera. From previous data we have collected, an IR focal length of 675 = 1.0849 degrees (for the active portion of video) For the entire width of the screen (including the black bars to the left and right), it would be 1.0849 degree * (1920/1280) = 1.62735 degrees HFOV. Because this is essentially a prime lens, the accuracy of the reported field of view is generally quite high and consistent across cameras.
As Antoine Cousyn, François Louange and Geoff Quick had assumed a HFOV of 1.3 degrees, the values they computed based on this number should differ accordingly.
The INS never aligned during this flight (which can happen) and so target coordinates are not displayed. The ground altitude of -489 FT and "North" indicator arrow are meaningless in part because of this as well. The turret azimuth and elevation orientations relative to how it was mounted on the aircraft (ticker tape displays) are not affected by this and are accurate.
Wescam documentation of the same can be found looking at the datasheet for the older MX-15 "True HD" turret: http://airbornesurveillance.com/pdf/mx_15_True_HD.pdf
Sensor #1 is the Thermal IR, and they are rounding the "1.0849" degree value to "1.1 degrees". The 26.7 degree value is for the 27mm focal length, and consistent with our own data logs as well.