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Yuri Knizhnikov 
  
I 
AL} = Ti AP. (12) 
op 
L - spacing interval up to observed points; bop - ophthalmic basis. 
In a limiting case the same relation binds a threshold of stereoscopic perception of depth (AL) and sharpness of 
stereoscopic vision (vs), Le. 
Lr 
ae vr (13) 
b. 
The quality and detail of a spatial image of observed object, which one is formed by a visual system of the person, is 
determined by a sharpness of stereovision. Geometrically it is characterized along an ophthalmic axis by a threshold of 
perception of depth (AL), and in perpendicular direction to an ophthalmic axis —- linear value of sharpness of 
stereovision (AL,), i.e. 
Al, = Lv; . (14) 
From the formula (13) and (14) follows, that observation without increase may be estimated as 
L 
AL = 5 AL. (15) 
op 
The relation (15) allows to proceed from direct observation of objects in a nature to the analysis of their discrete 
stereomodels. 
5.2 Properties of discrete stereomodels 
It is known, that basic parameter of representational properties of a single analogue image is its resolution, which one 
corresponds to the size of minimum object, separately recognized on a image. For single discrete image the value of the 
resolution (pix) estimates differently (Knizhnikov, Zinchuk, 1998): 
pix = pix’ * pix 4), (16) 
pix, and pix, - sizes of the parties of a pixel on a discrete image”, mm. 
However in both cases the indicated parameter characterizes the size of a minimum informative element of an image. At 
natural observations the minimum size of recognizable spatial object is determined by linear value of a sharpness of 
stereovision AL,. Enabling numerical equaling of detail of visible object (AL,) and its discrete image (pix), and also 
determining the size of a threshold of stereoscopic perception of depth of discrete images (AL,) at according to the 
formula (15), as 
AL ; (1 ) 
= DIX 7 
8 | - I , 
we have received 
Lo 2 
AL, - —-.(pix.tpixa)' . (18) 
bo 
  
* Pixel of a discrete image is defined as a pixel received at analogue-digital conversion of the initial optical or 
photographic image. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000. 509