26 



were inadvertently missed. The actual locations of the targeted dolosse distri- 

 buted over the north and south jetties are shown in Figures 15 and 16, respec- 

 tively. Numbers correspond to the originally established targets. Targets also 

 were established on the new CORE-LOC armor units installed on the heads of 

 the jetties during the October 1997 rehabilitation. Sixteen CORE-LOCs on the 

 north jetty and 12 on the south jetty were targeted. Their locations are shown in 

 Figures 17 and 18. In addition to the painted black crosses, the center of each 

 target was marked with a drill hole 0.64 cm (0.25 in.) in diameter and 0.64 cm 

 (0.25 in.) deep to aid in identifying targeted units in subsequent surveys. A typi- 

 cal target established on an armor unit is shown in Figure 19. 



Aerial Photography 



Aerial photography was obtained on the jetties with a Wild RC30 aerial map- 

 ping camera (9- by 9-in. format). The photographs were secured from a fixed- 

 wing aircraft flying at low altitude (183 m (600 ft)), which resulted in high- 

 resolution images and contact prints with scales of 1:1,200. Photographic stereo 

 pairs for the jetties obtained during the flights are shown in Figures 20-22. The 

 seaward photograph image (Figure 20) was used with the middle image (Fig- 

 ure 21), and the landward image (Figure 22) was used with the middle image 

 (Figure 21) in the stereo viewer to develop stereo models. The aerial photogra- 

 phy was obtained on 5 November 1998. 



Photogrammetric Analysis of Armor Units 



The stereo pair images obtained during aerial photography at Manasquan 

 Inlet were viewed in a Zeiss P3 Planicomp Analytical Stereo Plotter, and stereo 

 models were oriented to the monument data previously obtained. In the stereo 

 model, very accurate horizontal and vertical measurements can be made of any 

 point on any armor unit appearing in the print. After orientation of the stereo 

 model with monument data, x, y, and z coordinates were determined for the esta- 

 blished targets. As indicated earlier, the accuracy of this technique was on the 

 order of ±0.03 m (±0.1 ft) for the majority of the units. In addition to the data 

 obtained on the targets, additional horizontal and vertical position data were 

 obtained at other points on various dolosse through the stereo model. Without a 

 visual target, the accuracy of these analyses was on the order of ±0.09 m 

 (±0.3 ft). Analyses and comparisons of dolosse armor unit movement data from 

 the 1994 and 1998 photogrammetric surveys are presented later in this part of the 

 report as well as initial CORE-LOC armor unit target position data. 



Photogrammetric maps were developed from the stereo models, similar to 

 those done in earlier surveys. Tracings of plan view outlines of the visible armor 

 units as well as vertical data at various points were plotted that were 20 times 

 that of the stereo pair contact scale, to a scale of 1:60. In addition, rectified 

 photographs (orthophotos) of the jetties were prepared from the stereo model at a 

 scale of 1:300. Orthophotos combine the image characteristics of a photograph 



Chapter 3 Current Monitoring Plan and Data Comparison 



