„© C MONUMENT 
FIGURE 8. Illustrating process of location of monument by means of measure- 
ments from nearby offset targets. Distance AB between centers of offset 
targets is pre-established to a convenient fixed value (30 ft in the Atlanta 
Project). Monument C is located approximately equidistant from A and B and 
subtends an angle close to the optimum value of 90°. After monument has been 
so installed, distances BC and AC are taped and height differences between A 
and C and B and C are measured. From these quantities together with the 
photogrammétrically determined coordinates of A and B the coordinates of the 
monument can be computed. 
    
TABLE 2. Discrepancies at checkpoints of Atlanta Project. 
— ELA 
  
MEAN DISCREPANCIES (ft) b. 
POINT UN, 
rs i RY 
Y soi ratio (rdtiorgh) Lf ı (Up) 4 
| 10A -.524 .022 : 
| 108 -.572 .098 - 
| 11A 507 .011 
mmo 
| 12A „155 .151 
12B ‚205 ‚011 
18A A111 „321 
18B .387 . 340 
39A -.111 .007 
398 ‚018 -.515 
41A .069 -.032 
41B "2229 : Él: =o 5 
RMS: .310 ft .226 ft - 
(5.4um)*  (3.9um)* 
10 -.459 .141 - 
11 .181 -.077 - 
12 „127 ‚035 ie 
18 ‚226 „167 - 
39 - O71 -.239 - 
41 -.055 .009 t 
RMS: .230 ft :136 ft - 
(4.0um)* (2.4um)* 
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34A va gE .031 
34B - - t .141 
39A - - -.298 
39B E: " .046 
47A - x .018 
478 - „ „060 
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