Page 220 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

Chapter 6: Photogrammetric Techniques
199
Table I
Statistical data from conventional tape
measurement of control points.
RMS Residuals
Avg. Residual Redundancy
Points Used
Points Ignored Observations Used Observations Ignored Observations Rejected Depth Ref. Point
0.009 m 0.006 m 189
19
0 246 12
0 zero
Points:
Name X Y Z
A 0.900 A1 0.867
B 1.232
C 4.989
C1 6.271 D 4.336 D1 8.546 E 0.329
E1 0.617
E2 -0.905
F1 2.041 G1 6.281 J1 1.102 K1 -0.945 M1 -6.274 N1 -4.234 P1 -3.514 Q 3.173 X 3.575 X1 3.364 zero 0.000
-3.947 -3.809 4.847 -2.075 -0.955 -4.296 -5.256 2.020 0.297 0.429 2.666 -7.688 -8.996 -11.083 0.844 4.908 -5.949 -7.398 0.000 0.105 0.000
1.072
0.978 -1.995 0.979 -0.888 1.648 0.972 -0.760 -0.137 -0.122 -1.216 0.300 2.503 2.123 -0.039 -2.012 0.582 1.738 -0.300 -0.653 0.000
the other points. It can be seen that the accuracy of PhotoModeler is gen- erally better than the manual tape measurements from Site Surveyor.
Two sets of PhotoModeler tests were made using the grid frames men- tioned earlier. As the frames were of known dimensions and graduated, the coordinates of the graduations were recorded and then compared. It can be seen that the lightweight frame had a reasonable linear accuracy, but the rectangularity and “levelness” of the grid were poor indicating that the grid