CALCULATION OF A BLOCK OF STRIPS, ETC. 
17 
The output data, punched onto cards, consist for each stretch of : 
— a heading card, showing the serial number of the stretch, the number 
of T points, the calculated y} rotation ; 
— as many cards as are the T points, each showing the serial number of 
the point, its ground coordinates (if any), its transformed coordinates, the cor 
rected elevation, the distance from the axis. 
d) BL3 program - it performs operations e) and /) of para. 9 ; i. e. the cal 
culation of mean coordinates and elevations of the - points ; and the calcu 
lation, by the rigid-model method, of each stretch based on known points A 1 and 
on points Tu- in their mean plani-altimetric position. For the latter calculation 
we use program 400 of Note ( x ) almost unchanged. 
The output data, punched onto cards, are for each stretch : 
— a heading card, showing the serial number of the stretch and the coeffi 
cients for the planimetric and altimetric transformation of coordinates ; 
— as many cards as are the observed points, each showing the serial number 
of the point, the transformed coordinates, the ground coordinates (if any), the diffe 
rences between transformed and ground coordinates (if any). 
Anyhow, we think it preferable to perform operation e) of para. 9 by hand, 
i. e. the calculation of mean coordinates and elevation of the T^- points, in order 
to carry out an accurate critical analysis of the results, which cannot be left to 
the machine. 
Examples of calculation. 
14. — We give here the following practical examples : 
a) Calculation of a block of 2 stretches, performed only with the assistance 
of an ordinary Monroe or Brunswiga calculating machine, using the formulas 
shown in para. 11 c). This block, covering an area of about 100 km 2 (^ one sheet 
1 : 25,000) is based on 4 known points in total (2 for each stretch) ; the stretches, 
each of 6 photograms, are derived from two adjacent strips, taken in 1961 using 
a Wild RC 5 A camera, in the Verona district, the relative flight height being 
4500 meters. The bridging (free) has been effected by a Santoni IV stereo- 
cartograph, the scale of the model being 1:15,000, following the specifications laid 
down in Note ( 1 ). 
The calculation of the block, shown in Annex 1, has been performed on a 
special form, from which the succession of operations results very clearly. The 
five T points, in their mean positions resulting from the calculation, and the known 
points have later been used as control points for a new calculation of the two stret 
ches, by the rigid model method, in order to obtain the final coordinates of all 
observed points (see Annex 2). A further comparison between the latter and the 
ground coordinates of the check points proves the soundness of this procedure, 
as we obtained differences generally smaller than ^ 2 m in planimetry, and than 
1,5 m in elevation (see Annex 3).