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To get an unique block it is opportune 
to leave the cadastral (EN) coordinates 
and to go onto canonic (XY) coordinates, 
referred to the axes of the mean ellipses. 
The height over the ground remains as the 
third Z coordinate. A dedicated  computa- 
tion program easily performs this tran- 
aformation, as the 5 parameters of the el- 
lipses are known; and gives the new XY 
coordinates in the format needed for the 
block adjustment with bundles. 
2.3 - For the chaining observations we u- 
sed an analytical Kern DSR 11/H plotter. 
No correction for systematic errors was 
introduced. The phocal length (Wild P31 
camera) is 99.66 cm; the image size 12 x 
86 cm. 
The adjustment was performed with the 
excellent program  PATB-PC by  Ackermann- 
Klein [19881], with autocalibration and 
automatic gross error detection. For the 
El and E2 block computations, 25 resp. 14 
iterations were effected. The result was 
superior to any expectation, as 1t appears 
from the here below schedule 2. 
The Annex 2 reports the results obtai- 
ned for the control points. We must point 
out their exceptional quality, which shows 
the perfection of all ‘the. terrain and 
plant operations (fundamental net, its 
densification, intersections on the con- 
trols, instrumental observations, adju- 
stment computations). The final accuracy 
of the controls assures a centimetric  ac- 
curacy in the plotting. 
3. - The plotting 
3.1 - The above said canonic (XY) coor- 
dinates cannot be used for the plotting, 
except for the pairs which correspond to 
the vertices MN of the mean ellipse (fig. 
3). In fact, we need that everywhere the 
instrumental Y axis be normal to the elli- 
pse, so that the Y coordinate of a generic 
point P permits to deduce its distance to 
the mean ellipse, i.e. its altitude q in 
the Coliseum reference (shq).Therefore we 
must give a rotation © to the canonic 
coordinates of each pair, before plotting 
it; we obtain thus the "normal" coordina- 
tes (X'Y'). 
We can assume a mean 0 between the na- 
diral points of the two photos of the 
pair. This is not quite rigorous, as we 
should assume a different 0 for each point 
P; but, as we shall see later, the normal 
(X'Y') coordinates are only transition 
coordinates to arrive to the Coliseum 
coordinates, and a little variation of © 
has no influence on the final result. In 
fact, the purpose of the transition (XY) 
<> UO 'y'): is Only to obtain that the Y 
instrumental mouvement be quasi-normal to 
the monument's surface in the whole pair. 
A dedicated program TRASFH1 computes 
the © rotation for the central point of 
the pair, and effects the transformation 
from the canonic onto the normal coordina- 
tes. The normal coordinates thus obtained 
for the control points are used for the 
absolute orientation of the pair; its who- 
le plotting results therefore expressed in 
its particular normal system. The observa- 
tion is done in the usual way, and does 
not require special modalities. 
3.2 - .The last step is to transform the 
normal coordinates into Coliseum  coor- 
dinates, i.e. to get the transition 
(X*y'2')--2o. (shqp. 
This is effected by the program EL1, 
which: 
- gives to the normal coordinates (X'v*3 
a counter-rotation -90, thus reporting them 
to canonic coordinates (XY); 
- transforms these coordinates (XY) into 
Coliseum coordinates (sq). 
The third coordinate, i.e. the height 
of the point on the ground, remains un- 
changed in the three references (22 - 
h). 
The (shq) coordinates are the final o- 
nes, which are employed for the graphical 
or numerical representation of the whole 
wall, reported onto an unique reference 
  
Schedule 2 
Sigma naught Controls Mean resid. on the controls 
Block Image Terrain Horiz. Vert. Horiz. Vert. 
(microns) (m) (nr) (nr) (m) (m) 
E1 5.88 0.001 71 71 0.003 0.003 
E2 6.71 0.001 58 58 0.004 0.003 
  
335