as parameters of aerial photographs were similar in succee- 
ding periods, 
Isolines and height differences were the basis for mining 
interpretation, which resulted in conclusions concerning 
degree of ledge exploitation, further its exploitation and 
location of additional bore-holes. Moreover, examination 
of height deformations gave technical basis for reclamation 
of land, where exloitation was completed and surface was 
not already influenced by vertical movements. 
4,2 Volume determination 
For volume determination with the use of ODRA1204 computer, 
program called Huta 5D/74, elaborated by M.Sc, A.Kopcewicz 
in Computer Centre of Geodesy and Cartography,was utilized, 
Using this program one can determine volumes of embankments 
and excavations from the given horizontal or tilted plane, 
Program was elaborated under assumption, that heights of 
points acquired from net levelling will be the basic data. 
DIM was then adjusted to program requirements and volumes 
were determined from the given horizontal plane. The was 
one disadvantage in this program - need to determine poly- 
gon for each section and necessity to calculate each sec- 
tion separately. 
In the program, elaborated by the author of this paper 
for ODRA 1305 computer, on the basis of polygon for the 
whole object, polygons for particular sections are deter- 
nined. Considering requests of users algorithm was cons- 
tructed in such a way, to determine volumes from the given 
horizontal plane. Computation of volume for square grid 
mesh resolves in principle into two cases: 
- the whole area of grid mesh is located inside polygon 
- part of area of grid mesh is located inside polygon, 
In the first case volume is calculated according to 
formula: 
V-a^A Z sr 
where: a - length of side of square grid mesh 
- 206 =