E T V I S I O N M A N U A L
51
6
Right eye Corneal Reflection 2 found
7
Left eye Corneal Reflection 2 found
overtime count, 2 bytes
, unsigned integer. Shows how many records were lost prior to this one.
Typically contains the value zero.
Mark value byte
– will be last integer “Mark” value entered by user.
XDAT
– 16 bit integer set by external device.
CU video field number
– Internal field (or record) number kept by system. It is the number of eye
camera frames received from the eye cameras since the
ETVision
program was activated, and rolls
over to 0 after every 180 frames. Useful mostly for debugging purposes.
pupil_pos
– coordinates proportional to horizontal (0 to 320) and vertical (0 to 240) pupil position
with respect to the eye camera field of view.
Pupil_diam
– value proportional to diameter of the pupil image on the eye camera. More
specifically, the value is major axis of the ellipse shape identified as the pupil image. Note that this
value is computed to a fraction of a pixel. Note also that this value will not be affected by degree of
image ellipticity, and will not change (except for measurement noise) if the diameter of the actual
pupil does not change and camera to eye distance does not change. The units are eye camera pixels
multiplied by 100. To find the value in pixel units, the value recorded on the file or transmitted in
real-time must be converted to a float and multiplied by 0.01 (the scale factor shown on the chart,
above). This pixel value is the value displayed on the
ETVision
application (on the
Data Display
window), and the value shown by the Argus Science data analysis program,
ETAnalysis
.
Pupil_height
– the minor axis of the ellipse shape identified as the pupil image. Scaling is the same
as that described above for pupil_diam. Note that unlike “pupil diam" (major ellipse axis) the minor
axis of the ellipse image shape will change length as degree of ellipticity changes due to eye
movement, even if true pupil diameter remains constant.
cr_pos --
coordinates proportional to horizontal (0 to 320) and vertical (0 to 240) corneal reflection
with respect to the eye camera field of view.
cr_diam
– Diameter of the corneal reflection image in eye camera pixels.
gaze_coord
– horizontal and vertical coordinates of computed point of gaze with respect to the head
mounted scene camera 1280 x 720 pixel field-of-view (fov), multiplied by 10. Convert to float and
multiply by the scale factor 0.1 to get the pixel coordinate value. Note that fractional pixel positions
are represented. Also note that the values are signed. Negative values represent positions to the left,
or above the scene camera fov, while values greater than 1280 horizontal or 720 vertical represent
positions to the right of, or below the camera fov.
gaze_offset
– Manual offset added to horizontal or vertical gaze coordinate in scene camera pixel
units.
vergence angle
– The angle, in degrees, between the left and right eye lines of gaze.