Fig.3 Standard errors [cm] of adjusted 
tie points 
block size 4:13, 1:30000 
Og —10um £ 30cm 
4 control points for drift correction 
(datum transformation) 
rows/ 
columns 
of points| 2 3°4 5 67:8 
  
— "strip 
1 X 28 40 48 55 58 58 58 
1 Y 29 61 71 75 75 74 74 
1.2 29 83 94 94 89 84 82 
N 
< 
47 46 51 54 56 56 56 @ 
27 91 75 82 80 77 73 72 
3 X 56 45 41 42 43 43 44 
3 Y 91 48 50 52 53 53 54 
3 7 BO 69 66 63 60 57 56 
  
4 X | 55 44 42 43 44 44 44 
4 Y | 66 54 52 52 52 52 52 (9) 
4 Z | 92 68 67 65 64 62 62 
5 X | 59 47 42 41 42 42 42 
5 Y | 62 52 50 50 51 51 51 
52 | 7261 5765569352: 5K 2000 
  
  
0000 
0000 
0000 
R.m.s. accuracy of block 
[cm] [20] 
Msi Mol dia À Ha la its | Hz 
47 57 72 1.6 1.9 24 
52 72 17 2.4 
  
  
  
  
  
  
  
  
  
  
  
Fig.4 Standard errors [cm] of adjusted 
lie points 
block size 7x13 
q=60% side overlap 
4 control points 
rows/ 
columns 
of points| .2. 3.4 5.6 7 8 
  
=, strip 
1 X 28 37 41 45 47 47 47 
1 Y 28 55 62 62 61 60 60 (D 
$7 29.76 82 81 78 "76 75 
N 
= 
41 40 44 45 45 44 44 ® 
3 X | 40 34 33 34 35 35 35 
3 Y | 413940 41 41 41 41 ® 
3.2 |-58.52.52. 51.49 48.48... ] 
  
4 X | 41 35 34 34 34 34 34 
4 Y | 44 39 39 40 40 40 40 (à) 
4 Z | 54 50 48 47 45 44 44 A 
  
5 X | 42 36 34 33 34 34 34 
5 Y | 45 40 39 40 40 40 40 
5.2. 1:53 48.47.45 44 43 43-2000 
  
  
0000 
oooo 
0000 
R.m.s. accuracy of block 
[cm] [%] 
px} y |* #2 Eux | pig Lop, 
37 45 58 Le 1.5 1.9 
41 58 1.4 1.9 
  
  
  
  
  
  
  
  
  
  
  
  
  
Fig. 4 finally shows an example of a block with 60% side 
overlap. It contains 7 x 13 photographs which cover the same 
area as the example of fig. 3. The distribution of standard 
errors shows again high regularity, comparable to the other 
cases. The double overlap improves the overall accuracy by 
the factor 1.25, as compared with the example of fig. 3. That 
improvement is not as high as might have been expected. 
The reason is mainly, in this case, the magnitude (30 cm) of 
the standard errors of ground control coordinates. 
The examples of fig. 2-4 give a first impression of the ac- 
curacy results of GPS blocks, based on minimum ground 
control. The main features are quite regular accuracy dis- 
tribution within a block, a generally high level of accuracy, 
as compared with the photogrammetric measuring accuracy 
(00) of image coordinates, and weak dependence on block 
size. In the following it will be more thoroughly investigated 
how especially the accuracy of the ground control points and 
of the GPS camera air stations influence the resulting accu- 
racy of the adjusted blocks. Hereafter we consider only the 
overall horizontal (1, ,) and vertical (j,) r.m.s. accuracy of 
the blocks. 
4.3 Effects of ground control 
We want to investigate how the accuracy relevant features in- 
fluence the accuracy of adjusted GPS blocks. There is mainly 
the accuracy influence of ground control points and of GPS 
camera station positioning to be considered, in combina- 
tion with the various scenarios of ground control and datum 
transformation resp. drift error correction. In this section we 
study the influence of the accuracy ground control coordi- 
nates. The GPS accuracy is kept constant at OGps = 30 cm 
= 00, Which can be considered a representative value. Also 
the block size is kept constant at 6 x 21 photographs. Smaller 
and larger blocks would give almost identical results. It is also 
assumed that the precision of measuring the image coordi- 
696 
  
OY: PE" aml ga b oum Au nz M uu. 
4 cH 
mS. n9 em