0 the position of an object in the sky, expressed as an angle related to a distance on the horizon of the Earth --
The visuotopic displacement of each pair was measured as the difference in azimuth between the centers of the two aggregate receptive fields.
An equal angular velocity was then applied to all instrument azimuths.
The parameters that describe the rays' diffraction here are two, one more than for the ordinary: the altitude and the azimuth.
Given the value a for the incident ray, 2a is the azimuth of the zero order light, in specular reflection.
The horizontal axis for both graphs is used to plot either the azimuth or elevation of the test surface.
The orientation of the test surface varied in azimuth and elevation from trial to trial.
The azimuth is an arc of the horizon circle of this place, measured from a point taken as its origin.
Finally, elliptical functions were fitted to the threshold data and their area, ellipticity, and azimuth were measured.
