is held on the glass along the edges by means of electro-optical sighting. This comparator allows to isopal 
vacuum pressing [2]. Since the glass is manufactured measure in outer bunch of projecting beams spatial exclu: 
so as to meet highest accuracy standards, this method angles ¢x and ¢, for each cross placed on flattening Resul 
guarantees the value of RMS error induced by film glass of camera, as it is shown on Figure 3. photo 
unevenness of 1.5-20 mkm. 
A 
Along the whole field of frame calibration and coordinate à 
crosses are plotted with 10 mm step (1305 marks total). up i ra le "i 
Coordinates of these crosses are calibrated with 2.0-2.5 S ra. 6 tX 
mkm RMS error, which allows to consider film ps 3 S n : A 
deformation with maximum possible accuracy. — 7 i where 
; Ox, Oy - 
In order to compensate longitudinal shift of the image, 9, t % Y M. M 
flattening glass together with the pressed film moves Ox, 9y: 
with certain speed in direction of the spacecraft flight. f - ph 
Range of speed of image shift compensating movement S > X Xo, Yo 
is selected so as to permit prolonged exposure times for 
low sensitive but high resolution films. Four stationary i. In o 
marks are used to keep external orientation elements 9, photo 
constant at any position of flattening glass. These marks ZO coord 
are printed onto the film at the moment when shutter is % [5: +] 
completely opened. Location of stationary marks is 5 09 03* bas idpil Yo obiked £56 
shown on Figure 1, and layout of stationary mark and M Wher 
calibration crosses is shown on Figure 2. Figure 3. Measuring of spatial angles o, and o, glass 
AY envirc 
A B Angles ¢x and ¢, must have one and the same zero durinc 
Tw point corresponding to direction to the central cross of press 
photo camera, and the edges of these dihedral angles influe 
E zo. must be mutually normal, which fact provides neces 
' Tx rectangular coordinate system. Principal scheme of deter 
comparator is shown on Figure 4. and ir 
-140 image 
— zm photo camera 
c D 
V Pano 
Provk 
is nec 
Vie03 and i 
B uet y @ vi have 
Figure 1. Location of stationary marks. Mapp 
limb opog 
Ww. deper 
near : 
; To pi 
J sighting swath 
| obtair 
KVR- 
Figure 4. Principal scheme of comparator Was c 
Systei 
Sighting is assembled in special mount which allows it itis p 
to spin around two mutually normal axes. Sighting axis chara 
  
+ control crosses 
++ - stationary mark. 
Figure 2. Layout of stationary mark and calibration 
crosses 
passes trough the crossing point of rotational axis. V-V' 
axis is primary, it means that sighting rotation around 
this axis causes change of spatial position of 
secondary axis W-W'. Since, depending on 
observation perspective, crosses in comparator are 
transformed, the only rotation to be measured is the 
rotation around V-V' axis. At the same time one group 
of angles is measured, for example ¢x, and for 
measuring of another group of angles «oy precision 
rotation of camera by 90" angle is made. 
Sighting module of comparator has visual and photo- 
electronic circuits. Photo-electric device provides 
  
automatic observation of crosses in dynamic mode, pem 
which “act provides high accuracy and productivity of 
measurements. Spectral sensitivity of photo-electronic 
circuit corresponds to spectral sensitivity of 
Calibration of TK-350 camera, i.e. determination of its 
internal orientation parameters and distortion, is made 
using high precision spatial comparator with automatic 
  
106 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996