236 
SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
Results 
Analysis of variance based on photo interpretation of images of eight species 
replicated 19 times, showed the following: 
1. Interpreters. No statistically significant difference in accuracy was detected 
in observations made between any two photo interpreters on color film 
when their means were compared by Tukey’s range test. However, there 
was a difference on panchromatic film. 
2. Film. There was a highly significant difference between accuracies of inter 
pretation on color transparencies and panchromatic photographs. Inter 
pretations were significantly more accurate on color transparencies at all 
scales. 
3. Photographic scale. Differences in interpretation were highly significant 
between all scales on panchromatic film. On the color transparencies, the 
two larger scales were almost equally accurate; and both were significantly 
better than the 1 : 3960 scale at the .01 level. 
4. Tree species. Interpretation differences between tree species were highly 
significant. (Some tree species can be identified more accurately than 
others). 
Photo scole 
Fig. 1. 
str 
obus 
S' 
s 
^ Thujo occid 
✓ 
enta U 
s 
ЯГ- 
trifer 
a 
K3960 11584 i: 1188 
Photo scale 
Fig. 3. 
Panchromatic 
Pinus 
Thuja 
Pinus 
Pinus 
Picea 
Abies 
Acer 
Populus 
Betula 
»trobus 
iccidentalis 
resinosa 
bonksiona 
»pp 
balsomifera 
rubrum 
tremuloides 
papyrifera 
95 
81 
80 
80 
77 
73 
70 
59 
44 
Super Anscochrome 
Pinus 
strobus 
Pmus 
P.ceo 
Spp 
Pinus 
resinosa 
Thuja 
Abies 
bolsomifera 
rubrum 
Populus 
tremuloides 
Betula 
papyrifera 
97 
96 
88 
88 
86 
84 
73 
64 
56 
Fig. 1. Effect of scale and film on photo 
interpretation accuracy. Average of 5 in 
terpreters - all species 
Fig. 2. Species ranked in order of inter 
pretation accuracy - in per cent. Average 
of 5 interpreters - scale 1 : 1188 
Fig. 3. Effect of scale on photo inter 
pretation accuracy for 3 tree species on 
color film. Average of 5 interpreters 
Fig. 2.