terized by similar density on the whole area, . 
Measurement of arbitrarily distributed points is troub- 
lesome for stereo operator, Therefore making profiles 
along one stereoplotter axis is proposed, using automatic 
registration in assigned distances. It is recommended, 
that distances betwein profiles should be equal to dis- 
tances along profiles. 
Ihis way of observations assures uniformity of point 
distribution, location of points need not to be marked 
on contact prints or enlargements and does not require 
interruption of observations in order to mark measured 
points. Measurement is very quick and for the experienced 
Stereo operators fastness of work is frequently limited 
by efficiency of registration devices, The areas measured 
on adjacent Stereograms should overlap, as well as strip 
outside the boundaries of object should be measured, 
2,2 Computations 
Computation process begins with preliminary check of 
measuring data, removal of misregistrations and adjust- 
ment of model coordinates to the Scale of terrain coor- 
dinates. Next, X,y,2 model coordinates are transformed 
to X,Y,Z2 terrain coordinates. Helmert transformation 
is used for computation of plane coordinates, while 
heights are calculated, using formula: 
Z =. 2 + Zo+ aX + bY 
where: z - height taken from model 
X,Y,Z = terrain coordinates 
Zo - height displacement of origin of coordinate 
System 
a,b - coefficients, correcting height differences 
caused by residual errors of? leveiling 
On the basis of these data regular DTM is created in the 
form of square grid parallel to X,Y axis of terrain coor- 
dinate system. Heights of corners of this grid are obta- 
ined through interpolation, Among given points the closest 
- 202 — 
  
  
T: 
  
EE e MA ee