G VI 1-60 
PHOTOGRAMMETRIC ENGINEERING 
photos. Even with these, however, it has been found that the closeness of ob 
jects, and the unfamiliarity of such things as roof features and factory layouts, 
makes these last two topics least well known and, therefore, best interpreted 
after other experience and by elimination. Then, when this order or another 
of topical listing has been adopted, the interpreter needs particular topical 
procedures, similar to the examples that follow. 
TRANSPORTATION FEATURES 
Scales of 1/70,000-1/30,000* 
a. Outline areas with and without any kind of transportation lines. 
b. Mark the locations of the major and minor foci of transportation lines. 
c. Separate the more direct and less direct lines between major foci. 
Scales of 1/30,000-1/10,000 
d. For the more direct lines, determine the kind of vehicle on each. 
e. For the more direct lines, determine generally what is at the ends of 
the lines (e.g., city, water body, industry). 
f. For the more direct lines, determine generally what is at the ends of the 
lines which are tributary to them. 
g. For each more direct line, note its location with respect to the centers 
and types of foci, to the land between the foci (e.g., direct or indirect 
routes, continuous or discontinuous appearance), to the angle of junc 
tions with tributaries, and to the general distribution of buildings and 
other centers of human activity. 
h. For the less direct transportation lines between major foci repeat d-g 
above. 
Scales larger than 1/10,000 
j. For the transportation lines between minor foci and other centers of 
human activity, repeat d-g above. 
k. Determine specific characteristics of individual transportation lines and 
their associated features (e.g., width, function of adjoining structures). 
Drainage Features 
Scales of 1/70,000-1/30,000 
a. Outline the general areas of permanent water bodies (ocean, lakes, and 
rivers), seasonal water bodies, no apparent surface drainage, and under 
ground drainage). 
b. Outline ocean shorelines, larger permanent lakes, and trunks of major 
rivers. 
c. Determine general direction(s) of flow of water. 
d. Outline general areas with respect to types of drainage patterns (e.g., 
dendritic, trellis, karst). 
5 The three scale classes suggested in this paper are arbitrary determinations from research 
experience. The divisions are the same for every topic for purposes of convenience. The smaller 
limit of 1/70,000 is used because air photos usually are not made with smaller scales, and if so 
their usefulness is likely to be limited. Further, the placing of steps under these scale classes means 
that it is more efficient interpretation procedure to take them in the order given, and with the 
scales noted if such coverage is available. If not, several of the steps can be taken with photos in 
other scale classes and careful interpretation.