PHOTOGRAMMETRIC ENGINEERING 
for processing the images of successive points 
or places on the earth’s surface, to depict at a 
desired scale the portion of the earth covered. 
Progress is also being made toward reduc- 
ing if not eliminating the human operator in 
the stereoplotting operation. 
The development of the Orthophotoscope 
by Mr. Bean of the U. 5. Geological Survey 
has provided the necessary step for portray- 
ing the minute details of sensed information 
graphically in their correct relative positions. 
Means of automatically discriminating be- 
tween desirable and undesirable minute de- 
tails of sensed information have not been 
demonstrated satisfactorily yet, but time and 
effort are being expended toward this objec- 
tive. 
Progress has been and will continue to be 
made in automatically, or semi-automati- 
cally, converting collected data of a portion of 
the earth’s surface back into the three dimen- 
sional form at the scales desired. 
Transmission and representation of data 
between remote points have met with some 
success and are gradually improving. 
In many of thesestepsof the mapping proc- 
ess just enumerated, the electronic computer 
has or will play an important part. 
In analyzing these steps on a comparative 
basis as to readiness for utilization, either 
successively as automatic or semi-automatic 
operations in a mapping process, or as in- 
tegral parts of one overall system, the status 
seems to be as follows: 
For fixing the vehicle or actually the sensor 
in space the distance measurements, attitude 
determination, and environmental effects can 
all be recorded and fed into a computer along 
with geodetic data on points of origin. As 
mentioned before, the Hiran System is at the 
point where practical application on a large 
scale to iron out procedures is about all that 
remains. Also for operations covering small 
areas at lower altitudes the recently devel- 
oped airborne Tellurometer, with its ability 
to record distances simultaneously and re- 
peatedly from three ground stations, offers 
great possibilities for fixing the sensor in 
space at low cost. Unmanned air vehicles can 
also be considered for this application in the 
future. This step, or component of a mapping 
system, therefore appears to be at the stage 
where the degree of automatization depends 
on the requirements of other components, the 
coordination with them, and the practical 
economy of operation. 
With regard to sensors, the photographic 
processes are now adequate and certain of the 
electronic types of sensors show promise. The 
) 
situation appears to be that adequate results 
can be obtained by a photographic sensor 
with the degree of automatization determined 
by the other components, provided the 
weather 1s A greater degree of 
automatization, and a lesser dependence on 
favorable. 
weather conditions, can be obtained from cer- 
tain electronic sensors, provided a compro- 
mise is made as to quality and minuteness 
of detail. Considerable time and effort can be 
expected to be expended before electronic 
sensors produce results acceptable to users 
who are accustomed to photographic prod- 
ucts. 
[n the so-called map compiling step a num- 
ber of advancements have taken place. With 
the development of electronic computers the 
more or less dormant practice of analytical 
photogrammetry took on new life. Stereo- 
comparators have been redesigned and at 
least partially automatized. Direct or in- 
direct linkage with computers is under experi- 
mentation for performing analytical triangu- 
lation. The Helava development illustrates 
from  optical-me- 
chanical to optical-electronic stereoplotting. 
Then we have quite a bit of activity in the 
automatic stereoplotting field. Since this ob- 
the possible departure 
jective has been of interest to many and the 
subject of investigation and experimentation 
in several places I will discuss that of which I 
have knowledge with no assurance as to com- 
pleteness or chronological order. 
[f we wish to perform this operation auto- 
matically we must determine a way of uti- 
lizing electronics, mechanical means or a com- 
bination of both. We must determine the z co- 
ordinate for each xy position in the model. If 
we can determine the point of intersection of 
each pair of conjugate rays in the model 
electrically, while we mechanically scan the 
model, we will have accomplished our pur- 
pose. There are several approaches, both in 
the method of scanning the model and the 
method of determining the point of conjugate 
ray intersection, or to use a more familiar 
term, the point of image match. Let us first 
consider scanning the model. The scan can be 
made to traverse throughout the entire area 
occupied by the model determining the points 
of match only, or a match decision can be 
made as each point is encountered, and the 
data used to direct the scan generally towards 
the next most probable match point, i.e. along 
the surface of the model. 
Now let us consider the determination of 
the conjugate ray intersection or image 
match. Where the human eye makes the 
match optically, we must now determine the