MEASUREMENTS OF THE EFFECT OF UNBALANCED ILLUMINATION 
UPON ELEVATION READINGS WITH A MOVING FLOATING MARK 
IN A STEREOPLOTTER MODEL 
by 
Gilbert G. Lorenz 
Chief, Map Compilation Branch 
U, S, Army Engineer Research and Development Laboratories 
Fort Belvoir, Virginia 
" 
Precis 
Experiments are described in which a Stereoplanigraph is used 
for measuring the effect on elevation readings of unbalanced 
illumination in the stereomodel. Errors in elevation reading 
plotted against light imbalance ratio are presented for two 
speeds of floating mark travel based on observations made 
during this experiment. 
Des experiences au sujet de 1! effet de l'illumination mal 
équilibrée dans 1’ emploi d’un stéréoplanigraphe sont décrites. 
Dans ces-expériences-ci on a mesuré au moyen d’un stéréo- 
planigraphe les valeurs d” élévation ,indiquées sous les / 
conditions d^illumination sur le stéréomodele mal equilibrée 
à des degrés differents. Les erreurs dans les valeurs 
d’élévation ont été tracées en function de la proportion du 
mal équilibre d^illumination pour deux vitesses de la marque- 
flottante illuminée du stéréoplanigraphe. 
L^ 
X00 0X 0X x + x 
Professor Baetslé, in his paper "Several Questions of Physiological 
Optics As They Are Connected with Photogrammetry," has discussed a number 
of visual phenomena related to photogrammetry and has referenced a number 
of recent articles on other topics pertinent to his general Sub) Robe Two 
of these articles, one by Alfred Lit and one by À. L. Diamond, are 
with the effect of differences in luminosity received by the left and right 
eyes. Experimental measurements dealing with this effect when simulating 
contouring with stereoscopic plotting instruments form the basis for this 
paper. 
In a paper, "Significant Findings of a Stereoscopic Acuity Study," 
published in Photogrammetric Engineering in September 1959, Mr. Abraham Anson 
1/ Lit, A. - Depth-discrimination thresholds as a function of binocular 
differences of retinal illuminance at scotopic and photopic levels. 
Journal of the Optical Society of America (1959) 746-752. 
concerned 
  
2/ Diamond, A. L. 
phenomenon. 
- Simultaneous brightness contrast and the Pulfrich 
Ibid 1/ (1958) 887-890 
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