Full text: XVth ISPRS Congress (Part A2)

436 
STANDARDIZATION OF ANALYTICAL PLOTTER INPUT, 
OUTPUT, AND ALGORITHMS 
Chester C Slama 
National Ocean Service, NOAA 
Rockville, Maryland 203852. USA 
Commission II 
The conversion (in mapping) from traditional analog instrumen- 
tation to the analytical stereoplotter is a major step which 
requires a whole new look at the mapping process as it is 
presently performed. In the past, new forms of instrumentation 
were introduced and in most cases could be integrated into the 
process because they did not represent a radical change in 
procedure or the resulting process could be separated from 
standard products (e.g. orthophotooproduction). — Fortunately, 
the introduction of analytical processes were simplified 
because they were restricted to aerotriangulation which in most 
mapping facilities is separated from compilation. The analyti- 
cal stereoplotter, on the other hand, represents a new concept 
in instrumentation coupled with complete numerical (analytical) 
procedures. That is, it represents an instrumental concept 
that is applicable to both aerotriangulation (control densifi- 
cation) and compilation (data extraction)... To take full advan- 
tage of the concept one should review the present standard 
procedures and modify them where necessary to maintain continu- 
ity and standardization. 
Let us first look at what might be considered typical general 
steps (or processes) presently used in the production of maps. 
Major steps in the process are: planning; field acquisition of 
data; triangulation; compilation; and reproduction. Although 
all these steps could be made more efficient by applying modern 
digital techniques, the two that are most affected by the 
introduction of the analytical stereoplotter are the next to 
last two, namely triangulation and compilation. Through the 
years these two steps have evolved into two distinctly separate 
operations even though the utilize similar basic photogram- 
metric techniques. This evolution was spurred on by the 
development of highly precise mensuration instruments for 
triangulation whereas the compilation instruments were designed 
more toward ease of operation and versatility. In the past, 
the two separate operations could be tolerated because of the 
nature of the problem-beingisolved, That is, in order to 
extract data from a pair of overlapping photographs, the 
photogrammetrist must introduce seven known conditions of model 
Space (i.e., establish a state Of equilibrium for the model). 
These seven conditions are 3-rotations,s3 translations, and a 
scale. If absolute values are not given, he assumes certain 
conditions about one of the photographs, adjusts the adjoining 
photograph and creates the soecalled "relative orientation.” 
If, in addition, he has known.coordinates (7 values) o£ strate- 
gically placed points in the model area and makes the necessary 
adjustments of the photographs to fit these points, he has 
established the so-called "absolute orientation." To extract 
  
 
	        
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