1370 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975 
Figure 10 illustrates the arrangement of digital data in a sectional pattern. The sections can 
be in the X-Y, Y-Z, or X-Z planes. This pattern is most suitable for mapping closed objects such 
as parts ofthe human body. The computation of areas, volumes, mass, and perimeter distances 
can be easily performed when data are arranged in this pattern. 
In both the photogrammetric mapping and digitizing process, it is desirable to minimize the 
number of points to be measured. Thus, it is often necessary to measure only the points which 
represent change in slope, surface irregularities, or critical boundaries on the object. Such a 
procedure will resultin an irregular distribution of data points, as shown in Figure 11. In order 
to define the spatial position of each data point in such a pattern, all three coordinates (X, Y, 
and Z) of each point must be recorded in the data file. 
Since gridded and sectional data patterns are more convenient for computer processing and 
since the raw digital data are usually arranged in an irregular pattern, it is important that the 
application programs have the capability of converting irregularly spaced data into a gridded 
or sectional pattern. Either linear interpolation methods or surface fitting techniques can be 
used in the gridding of irregular data. The procedure and mathematical model to be used in 
any given problem will depend on the accuracy requirements, data density and distribution, 
and any prior knowledge regarding the shape of the surface being analyzed. 
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X 
Data File: 
LX 032 Yi X43 Yu3 oe Zp Xp Yan X22 Y22 ++" \ 
  
  
  
Fıc. 10. Sectional data pattern. 
  
  
    
Data File: 
  
X n A X, Y, Z 
  
  
Fic. 11. Irregular data pattern.