ibllshed by the 
mtour-line extrac- 
case when a part 
isually on photos* 
boundaries of plots 
i natural borders, 
rtraents differing 
st mensuration 
ity, age, etc*, 
sj relief, lines 
isotherms, etc* 
st management map- 
os* For this pur- 
ering of contour 
ne has been deve 
rst transferred 
photograph in whi- 
e up a photo out- 
from the photo- 
ered into the sys- 
0 outline conto- 
xtraction is done 
kage which reali- 
sharp' and *logi- 
ethod the positive 
e between sharp 
ned* It contains 
about contour li- 
e multiplied by 
to the source 
on the display 
d by means of cha- 
1 nonsharp' mask 
, and contour line 
rther processed 
Ls a scanning win- 
nparison of brigh- 
and pixels of the 
si P and with each 
le set logical 
sting the conditi- 
narked which cor- 
of the contour 
* 
: the contour net- 
ixtraction. It is 
>f the residual 
:hickening, thin- 
, etc* The proces- 
>f the analysis of 
>ods• The neighbo- 
:ive of the conto- 
itral point, that 
:ision about the 
j in the central 
:ects class defi- 
Their neighbour- 
latter marked or 
iple, to eliminate 
>f cells in which 
¡ent are analysed* 
ige cells in which 
led the ’current 
t quite broad nei- 
lell M . We shall 
tg-shaped zones 
etc* The side of 
■1 elements of the 
elements in the 
s to (2n+l)4-4» 
its make up one 
shown in a code 
corresponding to the n-byte word* 
Let us designate the first zone of 3x3 
around the cell M through Z,.* If we cut and 
develop it we shall have an octal-digit by 
te the contents of which reflect the state 
of the neighbourhood M . Let's divide this 
byte into X-half-byte ind Y-half-byte* By 
marking the contents on the XOY system da 
tum lines we shall get the matrix of 16x16, 
each element of which corresponds to one of 
the Z*-neighbourhood states* 
By means of grouping the states of the 
neighbourhood Z* by the definite feature 
into classes one can extract areas of these 
classes from the matrix and mark them with 
classes names: A, B, C, etc* For example, 
class A shows breaks of type I-I with which 
ends of the broken circuit get into the nei 
ghbourhood of 3x3. A more detailed descrip 
tion of different classes of the Z 1 -neigh 
bourhood states is given in (Elman 1 1982). 
Each class must correspond to the solution 
rule of the type: 'if A, then the unit must 
be sent to M ', or 'if A, then zero must be 
sent to M '* 
Each restoration procedure includes the 
following main operations: the current cell 
search, analysis of Z--neighbourhood of ea 
ch current cell, formation of the code-state 
and determination of the contents of X- and 
Y-half-bytes, entrance along X and Y into 
the state matrix to pick up the defect class 
and fulfilment of the decisive rule and tr 
ansition to a new cell. In this way we ma 
nage to single out up to 13 classes of con 
tour defects* 
3 CONTOUR NETWORK PROCESSING 
The binary contour network restored in the 
system is to be further processed so that 
it can be reduced to the form necessary for 
the submersion into the cartographic data 
base and for plotting* Certain demands are 
made to the network contour lines: all the 
lines must have standard thickness of one 
pixel of the display image, contiguous pi 
xels of the line must touch each other with 
their sides, there must be no breaks in 
closed circuits, etc* 
During the processing the transformation 
of the contour image from the pattern into 
the vector form with the cutting of the who 
le ramified network into separate unramifi 
ed sections called 'threads , the coding of 
threads depending on the meaning contents 
and position in the network, the analytical 
rectification of all contour lines hy the 
revision points read from photographs and 
the map, and the network map control are 
carried out* 
In order to process complex contour net 
works the digital sensing method has been 
developed (Elman 1982), On its basis the 
so called 'transport' algorithm is built 
which allows to follow any contour network 
along the lines in the forward and opposite 
direction* In each point of the contour the 
necessary processing can be done* 
The essence of the method lies in the fol 
lowing* Above the binary image located in 
the marker memory of the display system the 
inquiry program-control element (the digi 
tal probe) is defined* The probe can be mo 
ved by the program in the binary memory from 
the element of the digital image to the ad 
jacent element* Let relocations only in fo 
ur directions be allowed: to the right, to 
the left, up and down, and not allowed along 
the diagonals* We shall number this direc 
tions with figures from 0 to 3* When the 
probe from the current call moves in each 
of these directions we shall first call the 
se figures the direct addresses, and when 
it returns - the return addresses* 
We shall bind two more matrices with the 
same addressing with the matrix of the bi 
nary memory* They are intended for storing 
the direct and back addresses of the next 
probe step* When the probe makes the next 
step in the forward direction from the cur 
rent cell, the next address of the future 
direct step is entered in the memory of di 
rect addresses of this cell (before its mo 
vement begins the direct addresses matrix 
is coded with the initial address, for «ca 
mple, zero)* When the probe enters a new 
cell, into the memory of the return of this 
cell the address of the return from it into 
the former current cell is put* From each 
contour cell all necessary direct steps must 
be made in succession, and after the opera 
tion is over the return step has to be made* 
The network inspection is done in the fol 
lowing way* First the probe is put into the 
arbitrary contour network point, for exam 
ple by means of scanning* This point is con 
sidered initial, and is marked* For this 
point the initial direct address is extracted 
and by this address the neighbourhood cell 
sensing ls accomplished the aim of which is 
to test the three conditions allowing the 
movement of the probe into this cell: if 
there is a contour (marker) in this cell, 
if there was the probe there aarlier, and 
if the probe went beyond the frame borders* 
In meeting all these conditions the direct 
step into the sensed cell is made* Otherwise 
the next direct address is extracted* If all 
four direct addresses are exhausted then it 
is tested if the given cell is initial, and 
if so the network inspection is completed* 
Otherwise the return address is extracted, 
and the step to this address is made* In 
such a way all the contour network is ins 
pected* In the end points the probe is pre 
sent once, in linear points - two times 
(in the forward and opposite movement), in 
focal points - three or four times depen 
ding on the number of branches, and in the 
initial point - one unit more than in the 
point of the corresponding type. 
It must be noted that the probe can go 
through all the points of the arbitrary con 
tour network, even in case when the network 
has the broadening in the form of areas 
flood by the marker and when there are ho 
les in the areas* 
The described method is also used for the 
analysis of individual areas of the arbit 
rary form with holes, and not only contour 
networks* The processing of the contour 
olnts or area can be done after each fifth 
orward step (A-processing), before and af 
ter the return step (B- and C-processing), 
In order to transfer the network from the 
pattern into the vector form the following 
operations are carried out: with the help 
of digital sensing each closed area of the 
arbitrary form is described with its number, 
the probe's movement around the contour net 
work is set, on the direct step all focal 
ints are revealed and marked, and on the 
ck step chains of the threads coordinates 
are formed each of which begins and ends in 
focal or end points* To each thread numbers 
of two areas lying on its sides are assign 
ed* As a rule the thread is represented in 
the machine as a broken line that is why