553 
and f is the focal length of the camera, or the principal distance of the 
photographs used in the model. 
Let C be the rotation matrix that rotates from local to camera coordinates 
for each camera station: 
[6] - (&) (AD (à (13) 
where (Ry) is the photogrammetric rotation matrix formed by the sequential 
rotation matrices. These matrices are the primary uw matrix about the X 
axis, the secondary $ matrix about the Y axis, and the tertiary « matrix 
about the Z axis: 
(Ry) 7 [x] [6] [o] (14) 
Then, the rotational parameters for each photograph in the model can be 
obtained by: 
zi 
w, = sin (C,3) 
T “ean be yey 
d rca 13/633 
TE ceils. (15) 
Re a 12^"22 
The stereomodel setup is accomplished by entering the computed model 
parameters as defined in equations (11) and (15) into the computer of the 
analytical stereoplotters. The immediate result is a stereo model that is 
equivalent to a stereo model obtained through the ordinary processing of 
relative orientation. Contour lines are then compiled. 
Because the model orientation parameters are computed using the adjusted 
SEDR data in the control net adjustment, stereo models derived with these 
parameters are close to those derived from the absolute orientation 
parameters. The computation of absolute orientation does not change the 
model orientation parameters significantly except where map projections 
differ. 
Software for this technique has been developed on the analytical 
stereoplotters. Adjusted camera positions and attitudes of the 714 Viking 
pictures have been stored into a moving head disc so that all the 
computations can be done in real-time processing. As soon as the plotter 
operator enters the identification of the pair of photographs of the model 
and performs the interior orientation, a stereo model is established 
immediately. In the situation where the operator decides to perform an 
absolute orientation of the model, all he has to do is to enter 
identification of control points desired to be used. The computer searches 
those control points from the master file in the disc and performs the 
absolute orientation immediately. About 3,000 control points of Mars 
established from the Mars planet-wide control network (Wu and Schafer, 
1984) have also been stored on the disc in both geodetic and Cartesian 
coordinate systems. Using this technique, Mars maps at various scales have 
been and are being compiled. The smallest contour interval yet attempted 
with Viking Orbiter pictures is 20 meters.