Pupil diameter measurement errors as a function of gaze direction in corneal reflection eyetrackers

Whispering gallery mode (WGM) resonance is used for the diameter measuring method of a microsphere smaller than φ 1 mm. It is aimed to achieve measurement accuracy better than 10 nm. There are two electromagnetic modes for WGMs, and then mis-detection of the electromagnetic mode expands measurement errors more than 100 nm, so it is indispensably to distinguish the electromagnetic mode. As theoretical simulation implies, polarization mode of WGMs can be selectively excited by controlling polarization of the incident light in optical coupling. Based on the analysis, it was proofed experimentally that the polarization of WGMs could be classified. As a result, the diameter measurement for a microsphere was performed with measurement error of ± 1 nm.

Download Full-text

Improving pupil diameter measurement accuracy in a remote eye tracking system

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1071181319631176 ◽

2019 ◽

Vol 63 (1) ◽

pp. 49-53

Author(s):

Joseph T Coyne ◽

Noelle Brown ◽

Cyrus K. Foroughi ◽

Ciara M Sibley

Keyword(s):

Eye Tracking ◽

Measurement Accuracy ◽

Pupil Diameter ◽

Tracking System ◽

Reference Value ◽

Cognitive Tasks ◽

Diameter Measurement ◽

Average Difference ◽

Fixed Size ◽

System Data

Pupil diameter (PD) has been used to track changes in mental effort across a broad range of cognitive tasks for over 60 years. PD is often measured from remote eye tracking systems, which all have the same limitation: the lack of a known reference value to convert the pixels captured within the systems to millimeters. Researchers frequently normalize their data within an individual to overcome this issue, however recent studies have found individual differences in resting PDs. This paper investigated the use of a fiduciary marker of a fixed size and an individual’s interpupillary distance, as known reference values. Both techniques substantially improved the accuracy of PD data compared to the unadjusted system data. Further, the average difference between both techniques and the uncorrected pupil diameter was just under .4mm, which is approximately the equivalent of most studies finding differences in cognitive load.

Download Full-text

Effects of upper stem measurements on the predictive ability of a variable-exponent taper equation

Canadian Journal of Forest Research ◽

10.1139/x98-120 ◽

1998 ◽

Vol 28 (7) ◽

pp. 1078-1083 ◽

Cited By ~ 12

Author(s):

Antal Kozak

Keyword(s):

Measurement Errors ◽

Variable Exponent ◽

Predictive Ability ◽

Diameter Measurement ◽

Breast Height ◽

Taper Equation ◽

Taper Equations

Like several other taper equations, the predictive ability of Kozak's (1988. Can. J. For. Res. 18: 1363-1368) variable-exponent taper equations can also be improved by an additional upper stem outside bark diameter measurement. This study indicated that improvements were small and were mainly restricted to increasing the precision of the estimates. Also, it was demonstrated that if additional diameter measurements are justified, they should be taken between 40 and 50% of the height above breast height for greatest improvement. Measurement errors in upper stem diameters and in their heights above breast height affected both the precision and bias of predictions.

Download Full-text