44 
Photogrammetric Applications of the DTM 
  
The DTM is a useful tool to the USFS in making the transfer of 
photo-delineated planimetric detail to maps or other aerial pho- 
tographs. Along with the electronic computer and the DTM, the 
technique uses an X, Y digitizer.and plotter. The procedure is 
as follows: | 
| 
FIRST ITERATION 
MEASURED X, Y 
SECOND ITERATION 
PHOTOGRAPH 
eo restr a ees) 
remets = permette tte 
  
7 
fr CAMERA LENSE 
  
  
  
  
    
N FIRST HORIZONTAL 
CORRECTION 
   
  
  
  
VERTICAL COR— 
FROM DTM 
TERRAIN ^71 
   
  
  
SECOND VERTICAL 
CORRECTION 
    
A 
TERRAIN — 
   
  
SECOND HORIZON- 
| 
| 
TAL CORRECTION | 
  
  
do. SEA LEVEL 
Fig 6. Combination Resection and DTM 
  
og  _ d 
CON »—« — 
n