Fıc. 5. Vertical sketchmaster, 1942 model. 
Floore Radial Intersectors‘® 
In 1938, S. P. Floore developed a method 
of compiling a radial triangulation net in 
which the underlying map base was not 
covered and in which bulky or expensive 
templet cutters were not needed. In this 
method, slotted intersector arms Figure 6, 
made of metal are used instead of slotted 
templets. Each arm represents a radial; 
the radials emanating from a given point 
are bolted together to form an intersector 
unit. These units are then assembled in a 
manner similar to conventional slotted 
templets. 
Rectoblique Plotter; Photoangulator! 
These two instruments, Figures 7 and 8, 
were developed by J. G. Lewis, during the 
war years, 1941-45, the photoangulator 
being an improvement on the rectoblique 
plotter. The purpose of both instruments 
is to obtain, by mechanical means, true 
  
Fic. 6. Radial intersector assembly. 
HISTORY OF PHOTOGRAMMETRY IN THE UNITED STATES 
horizontal areas from an oblique photo- 
graph. In particular, the instruments are 
used to determine horizontal directions of 
rays drawn from the nadir point of a set of 
three trimetrogon photographs to image 
points on the oblique photographs. The 
rectoblique plotter consists of a tilted table 
upon which are mounted two arms of dif- 
ferent lengths connected by a bar free to 
slide parallel to the horizon. The left, or 
photo arm, is made of transparent mate- 
rial, and is pivoted on the table at its lower 
end at a point corresponding to the photo 
nadir point. The right arm is known as the 
templet arm and pivots about a point at 
  
Fic, 7. Rectoblique plotter. 
  
Fic. 8. Photoangulator. 
its lower end which corresponds to the 
ground nadir point. The templet arm gen- 
erates angles in a horizontal plane which 
correspond with angles described by the 
photo arm in the plane of the oblique ex- 
posure. 
The photoangulator differs from the 
rectoblique plotter in that its photo arm 
and templet arm operate from a common 
pivot. : 
Stereoblique Plotter? 
The stereoblique plotter, Figure 9, was 
  
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