-- Y --
Term Definition/Description Source
yaw 1. (air navigation) The rotation of an aircraft about its vertical axis so as to cause the aircraft's longitudinal axis to deviate from the flight line. Also called crab. 2. (photogrammetry) The rotation of a camera or a photograph coordinate system about either the photograph z-axis or the exterior z-axis. 3. In some photogrammetric instruments and in analytical applications, the symbol k may be used. HDBK-850
yaw angle See angle of yaw. HDBK-850
y-axis 1. (JCS) A vertical axis in a system of rectangular coordinates; that line on which distances above or below (north or south of) a reference line are marked. especially on a map, chart, or graph. 2. The line which is perpendicular to the x-axis and passes through the origin. HDBK-850
y-coordinate The y value, ordinate, coordinate of a point in a plane Cartesian system obtained by measuring parallel to the y-axis. ISO/TC 211
y-coordinates See ordinates. HDBK-850
y-displacement A component of image displacement. When a point image is to be located by coordinates with respect to rectangular axes, y-displacement represents the distance moved in the y-direction. HDBK-850
year The period of about 365 1/4 solar days required for one revolution of the Earth around the Sun. See also anomalistic year; calendar year; eclipse year; fictitious year; great year; sidereal year; tropical year. HDBK-850
y-level See wye level. HDBK-850
y-parallax The difference between the perpendicular distances of the two images of a point on a pair of photographs from the vertical plane containing the air base. The existence of y-parallax is an indication of tilt in either or both photographs, or a difference in flying heights, and interferes with stereoscopic examination of the pair. Also called vertical parallax; want of correspondence. HDBK-850
y-scale (JCS) On an oblique photograph, the scale along the line of the principal vertical or any other line, inherent or plotted, which, on the ground, is parallel to the principal vertical. HDBK-850
y-swing method See one-swing method. HDBK-850
y-tilt See pitch. HDBK-850

Last Updated by Mark Owens 17 February 1999.