80 REPORT OF COMMISSION VII 
C. CULTUURTECHNISCHE DIENST AT UTRECHT (CULTURE PLANNING) 
This institute mainly uses aerial photographs as an aid in arriving at prelimi- 
nary estimates relative to the re-allotment of land. First, a map on a scale of 
1:5,000 is compiled from copies of cadastral plans. From this are successively 
derived: altitude maps, property maps, culture maps, and maps for water 
courses, artificial objects, and soil types. Photo-interpretation is a valuable aid 
in the preparation of all these maps. Moreover operation diagrams for field 
activities can easily be framed with the aid of the aerial photographs. When 
the cadastral maps are very much out of date, one passes on to a base map 
photogrammetrically made. Side by side with this base map, made from aerial 
photographs, the photograph remains indispensable for interpretation, as only 
a very small part of the data can be mapped from the photograph. 
Interpretation takes place with the aid of a pocket stereoscope, especially 
for the purpose of estimating small field slopes. 
Vertical photographs on a scale of 1:5,000 are preferred or enlargements up 
to this scale. At the same time these are used for composing mosaics. Concerning 
the season of taking photographs, this service prefers those periods in which 
differences in growth find expression, either in consequence of humidity, or in 
consequence of great dryness. 
D. STAATSBOSBEHEER AT UTRECHT (FORESTRY) 
In two sections of this service, viz. the section for Forest Statistics and the 
section for Forest Inventory, aerial photo-interpretation is used. By the first- 
mentioned section photographs are used as an aid in making forest maps con- 
taining statistical data. The interpretation, which is performed either with or 
without a stereoscope, has as its purpose to identify wood stands, road planta- 
tions and uncultivated grounds; to determine the exact boundaries of each of 
these parcels; and to delineate boundaries within each parcel for the various 
kinds of wood, uncultivated ground, species and the like. The subsequent field 
check is to ascertain more precisely the necessary kinds of wood, ages and possi- 
ble alterations after photographing. Vertical photographs on a scale of 1:10,000 
taken in the leafless period are preferred. 
In the forest inventory section aerial photographs are used both for the 
cultural interpretation of a forest stand and for the entire or partial mapping 
of it. Not only does the photograph give a fine general view of the composition 
of the forest complex, but also an orderly image of the differentiation of the forest 
stand. After the boundaries of the forest stand have been copied on the field map, 
the necessary field reconnaissance is made. Aerial photographs on a scale of 
1:20,000 are of good use to this section. 
E. RUILVERKAVELINGSDIENST VAN HET KADASTER AT THE HAGUE (REALLOT- 
MENT) 
Photo-interpretation is applied by this Service in the following cases: 
1. For valuation of the ground. By means of interpretation classification 
boundaries of soil types are recognized and delineated, after which by soil 
survey the valuation can be completed. 
2. For the elaboration of the scheme of roads and watercourses, wherein 
the existing field condition must be taken into account. This operation can partly 
be performed in the office. 
3. As an aid in delineating land parcels which are to be projected on the 
exact base maps. For reallotments in which the existing condition doesn't 
entirely disappear, the aerial photographs are used for aerial mapping at the 
  
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
   
   
  
  
  
  
  
  
   
    
   
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