NOMOGRAMS FOR TORSION AND DIRECTION OF REGARD
Glenn Ansel Fry · Optometry and Vision Science · 1968
Nomograms have been prepared which make it possible to transform a specification of the direction of regard in terms of any pair of angles (latitude, longitude, elevation, azimuth, meridian, eccentricity) to any other pair including mixed pairs such as elevation and longitude, which are used for tangent screens. These nomograms can also be used for transforming a specification of a direction in the field of view which has its origin at the entrance-pupil. Nomograms are also provided for computing the torsion of a troposcope target and also the torsion of the eye at the primary position of the line of sight. A formula is presented for computing the torsion at a secondary position of the line of sight.