Prior to this photography, the Hasselblad photos had been submitted to comparative 
tests on recognition of species, crown counts and stratified crown counts. 
Panchromatic B&W, infrared B&W and colour were available as prints. The 
infrared colour films were reversed to positives. 
The infrared B&Wphotos were unfortunately of such poor resolution and contrast 
that they had to be rejected right at the beginning of the tests. 
RECOGNITION OF SPECIES 
Emergent species of Couratari, Parkia, and Rheedia could be recognized on 
panchromatic B&W photos. When not emergent they were difficult to recognize. 
The same can be said of all other species in the various strata of the rain forest. 
Variation in crown shape and tone within one species were so great that these 
elements could not be used for recognition. 
The colour filmtypes offered little better possibilities. Parinari species, which 
have brownish foliage, could easily be detected. Colour differentiation on infrared 
colour was much greater than on colour. Unfortunately, particular colours and 
hues could not be trusted to belong to a definite species. The erratic periodicity 
of most tree species is the reason. Even on a single tree the foliage may be in 
various stages of development. 
On no filmtype could any of the commercially important species like Goupia, 
Dicorynia, Ocotea, or Vouacapoua be recognized with certainty. 
TREE COUNTS 
Provided that aerial photographs are of a large enough scale and of such quality 
that photoplots can be located without complications due to model deformation, 
the number of trees per area unit is one characteristic of the tropical rain forest 
which may be estimated by photo-interpretation with acceptable accuracy. 
To compare the usefulness of three available filmtypes with regard to crown 
counts, twelve photoplots were taken with principal points as centres. First the 
principal point was located in the forest. With this point as centre square plots 
of one hectare were then laid out, whereupon their corner points were pinpointed 
on the photos. The plots could then be drawn on the photos. Crowns were 
delineated on the photoplots and then counted under a Galileo Santoni scanning 
stereoscope with times magnification. Borderline crowns were counted if one 
half or more than one half of the delineated crown was within the plot. On the 
fieldplots all unsuppressed trees were counted. Actually this meant that very few