Yuri Knizhnikov 
  
R; - resolving power of the linear photographic test objects (R; =25, 30, 35, 40, 45, 50 mm"). Empirical contrasts AD i 
have been obtained due to relationship, which is shown in figure 2. 
Empirical values of the modulation transfer function Tem(R;) have been calculated as: 
T, (Ri) = AD ni / AD", (8) 
The experimental data obtained (table 1) show that divergence between theoretical contrasts AD and empirical ones 
AD, is equal to 0,02-0,04 Bel. This result confirms the correctness of suggested equation (formula 6) for estimation of 
discrete space images representation properties. The relationship described allows studying the influence of the A/D 
conversion on the cartographic interpretation truth (completeness). This one was used for 1:25 000 topographic map 
updating based on space images interpretation. 
2.3 Estimation of the A/D conversion influence on the cartographic interpretation quality 
Topographic objects mapping quality may be obtained due to cartographic interpretation truth criteria. Cartographic 
interpretation truth (or completeness) is determined as weighted average probability of mapped objects recognition from 
space images Q, which proposed in (Bezhic et al., 1993): 
n 
Qz Y P(N;) - P(M;), (9) 
i=1 
P(N;) - probability of i-type's topographic objects true recognition from space images (each type includes such object's 
group as relief objects, hydrography, road set, vegetation and others); P(M;) - a relative frequency of i-type objects 
n 
occurrence upon created map contents; n - a number of topographic object's types; > P(M;) = 1,0. 
iz1 
Extensive statistical investigations have allowed to calculate the values of P(N;) under 45 mm ! resolving power space 
images recognition and the parameters of P(M;) for 1:25 000 topographic map (Bezhic et al., 1993). 
A/D conversion causes a decrease of mapped objects recognition probability under discrete image interpretation P(N;); 
that calculated according to (Zhivichin, Sokolov, 1980): 
AD"7AD' à 
P(Ni - P(Ni) (10) 
This relationship transforms in agreement with formula (8) as: 
P(Ni)a = P(N;) 9) (11) 
Mapped objects recognition probabilities were established due to interpretation of the 45 mm'' resolving power discrete 
space image, which produced under 0,0075 mm scanning aperture and 0,0075 mm sampling rate. Then weighted 
average probabilities were calculated using formula (9) for continuous Q and discrete Q; space images interpretation. 
Comparative estimation of Q and Q; values shows that A/D conversion of the continuous (photo) images characterized 
by the 45 mm resolving power under 0,0075 mm scanning aperture and 0,0075 mm sampling rate produces to the 
losing upon the average 10 per cents of the initial cartographic information. It is necessary to take account of this 
information loss in agreement with specific properties of the discrete space images visual interpretation (Knizhnikov, 
1997). 
  
504 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000.