where A is an value of kth element of lateral histogram, and n is 
shift of zone relative to the etalon. 
Output pitch increment value selection 
To select Aq value we take into account: 
e number of zones with the same value of AQ; 
® contrast in each zone: 
* correlation function value in each zone. 
The value Aq is selected, for which there was a greatest number 
of coincidences on zones. With other conditions being equal 
preference is made to zones with the greatest contrast, and the 
value of function of correlation is used as some threshold 
restriction. The number of coincidences is at the same time 
characteristic of reliability of a value produced by the block. 
Current pitch angle value calculation 
The pitch angle increment value (Ao) that was selected on the 
previous step is added to some value that was accumulated and 
that is current pitch angle value. In case when for n consecutive 
Ag = 0, we set the accumulator value to 0. 
Road situation analysis 
Task of this procedure is the prevention of situations, when 
some moving object, or it’s part, get into an analyzable 
fragment of the image. For this purpose the output data of the 
block of obstacle detection and tracking are used. 
Determination of new position for zones on course angle 
The position of zones on curse angle and angle of elevation is 
determined. Position on course is determined according to 
above mentioned method. Zone positions on an angle of 
elevation are displaced so that to compensate vehicle pitch 
deviation, i.e. zones are displaced by the angle equivalent to the 
pitch angle deviation, taken with opposite sign. 
Calculating of lateral histograms of etalon images and 
calculation of contrast in every zone 
In case when some zones do not satisfy to restrictions on 
contrast, the choice of a new position of zones is made. 
3. DEFINITION OF PITCH ANGLE OSCILLATIONS, BY 
RESULTS OF ROAD MARKING LINES DETECTION. 
Pitch angle calculations using road marking lines in a near zone 
is based on determination of marking lines point of convergence 
position on stereo images. Since cameras of a stereopair are 
adjusted then all parallel lines on images will converge in one 
point, i.e. marking lines on images represent a bunch of straight 
lines. Here, coordinates of points of convergence of parallel 
lines on right and left images will coincide. Thus, to calculate 
point of convergence coordinates any pair of the detected 
marking lines could be used (for example, left on the left image 
and left on the right image). Depending on what lines were 
detected, point of convergence coordinates are determined by 
one or another way. 
After detection of fragments of road marking lines in the area of 
interest of the image these fragments are represented as 
segments of straight lines in focal planes of the left and right 
TV-cameras. This segments have the top and bottom 
boundaries, which can coincide with the appropriate boundaries 
of areas of interest (solid road marking lines), or to not coincide 
with them (dash road marking lines). Therefore outcome of 
primary measurements are the coordinates of boundaries of 
these segments of lines in focal planes of TV-cameras of 
stereopair in a co-ordinates (Z - horizontal axis, Y - vertical 
axis) which origins coincide with principal points on focal 
planes of cameras: 
(Z11> V11) and (213, V13) — top boundary coordinates on the left 
camera; 
(Z14, y14) and (zi; V12) — top boundary coordinates on the right 
camera; 
(Z21, V21) and (223, V23) — bottom boundary coordinates on the left 
camera; 
(Zo4, y24) and (z», y»;) — bottom boundary coordinates on the 
right camera. 
The points having such coordinates, can lay on boundaries of 
areas of interest or be inside these areas. 
As a result of one act of measurements any of above mentioned 
pairs coordinates can appear (line is detected) or to not appear 
(line is not detected). 
The tangents of angles between a vertical axis (Y) and these 
segments of straight lines (directed from below upwards) can be 
defined by the obvious formulas: 
fj, 3 - tangents of angles of declination of the left and right lines 
on the left image, 
ls, 1 - tangents of angles of declination of the left and right lines 
on the right image, 
and also the coordinates of points of convergence of straight 
lines, on which lay these segments (3, zy). At lack of errors in 
direct measurements and the parallelisms of optical axes of 
cameras coordinate of points of convergence, obtained on any 
pair segments of straight lines should coincide (since point on 
convergence is the indefinitely remote point). 
The analysis of results of direct measurements obtained on 
experimental registration in various conditions, shows, that only 
bottom boundaries of straight lines segments in a near zone are 
measured with adequate accuracy. The angles of declination a 
often are determined with the large errors, which has especially 
strong effect on errors of calculating of vertical coordinate of a 
point of convergence y, if this point is determined by simple 
geometrical construction. The experience of experimental 
registration processing has shown, that this factor (as well as all 
connected with the vertical channel) very strongly influences 
process of road marking lines tracking, both in vertical, and in 
horizontal planes, greatly increasing required sizes of areas of 
interest. 
Therefore, to increase an accuracy of measurement of pitch 
angle 0 and roll angle Y of stereosystem relative to a Near 
Zone plane the method of dynamic correction of direct 
measurements was developed. 
Direct measurements are understood as measurements, which 
can be obtained on one image frame of a stereosystem by 
geometrical constructions on two images formed in stereopair 
without use of outcomes of dynamic data processing. 
The offered method consists in that the primary measurements 
are grouped so that to express the obtained generalized 
parameters through constants and slowly varying parameters, 
and to use as / and 4 values outcomes of a filtration (average) of 
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