Besides such estimation of a current pitch angle is made after 
detection of road marking lines. In this case for construction of 
zones of search of road marking lines on the current image it is 
necessary to use extrapolated value of a pitch angle at the 
moment of this frame creation. In conditions of strong 
disturbing effects on the car body (for example, at abrupt 
braking) occurrence of significant distinctions between a true 
pitch angle and its extrapolated value that can result in failure of 
road marking line tracking in a near zone is possible. 
In case of problems with road marking lines detection in NZ the 
current estimation of pitch angle oscillations can be made based 
on determination of vertical movements on the scene image of 
remote objects. Solution of the task is complicated because 
sensors are located on the moving carrier which generally 
makes maneuvers. Except for underlying surface there can be 
both remote, and close located objects, including moving, on the 
scene. It causes necessity of usage of the dates of an own 
angular velocity sensors and methods of the situational analysis. 
The method of a pitch angle current value determination is 
considered based on parallel, independent calculation of this 
angle using road marking lines in a near zone (NZ) and with the 
help of correlation tracking of remote objects with the 
subsequent decision making about choice of a true value of a 
pitch angle. At that it is supposed, that in the system in addition 
to the videoinformation processing the dynamic data processing 
is made which allows to form (get, calculate) a current 
estimation of a pitch angle value on the basis of a Kalman filter 
and to get extrapolated pitch angle value on the moment when 
the following image frame is formed (obtained). 
Fig. 1 presents the general principle of data processing 
organization. The procedures which are considered in this paper 
are highlighted. 
2. DETERMINATION OF PITCH ANGLE OSCILLA- 
TIONS, ON THE BASIS OF THE REMOTE OBJECTS 
CORRELATION TRACKING. 
To understand logic of organization of the procedure we 
examine de-correlating factors, i.e. factors resulting in a object 
image alteration on time-apart images. Such factors could be: 
* scaling of the object that is tracked when the distance to 
this object changes; 
e the displacement of object image when line of sighting of 
the object does not coincide with a vector of a velocity of 
the vehicle; 
e vehicle roll angle perturbations; 
* moving object (or it's part) getting in an analyzable 
fragment of image; 
* sudden modification of light exposure of a scene (for 
example, when going under the bridge); 
e vehicle maneuvering on the course. 
Besides even if tracking of the image fragments that correspond 
to the remote objects, is successful, there can be situations 
resulting in erroneous determination of pitch angle oscillations 
values. The typical factors resulting in errors determination of 
pitch angle oscillations are listed below: 
e low contrast of an analyzable fragment of the image; 
® some objects or patterns on the road surface get into a 
bottom part of an analyzable fragment; 
  
New image load 
' 
Calculation of extrapolated value 
0 
+: 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
; At, 9,0, 
Determination of A0 and 0 by the s d 
correlation method 
Selection of the 0 current value 
ie 
O, At, Y; 
Determination of areas of interest 
for road marking lines detection © 
in NZ 
T 
Selection 0 by the road marking 
lines 
  
  
  
  
  
  
  
  
  
| Selection output 0 
| 
Fon 0 
  
  
  
Fig. 1 
elements of bridge, road sign, and so on, get into the upper 
part of analyzable fragment; 
© some object situated close by the road gets into the 
analyzable fragment when the road is about to turn; 
road curvature in a vertical plane. 
To determine pitch angle current value on the basis of 
correlation tracking of remote objects the estimation of pitch 
angle oscillations is used, i.e. increment/decrement of a pitch 
angle on a time interval between two successive frames. 
The method of correlation binding of fragments of the previous 
image (used as the etalon image), with appropriate fragments of 
the current image is applied for this purpose. 
At that, as it is necessary to determine only pitch shift, image 
lateral histograms are used for correlation matching instead of 
images themselves. 
To ensure steady operation of algorithms some fragments of the 
image are exposed to the analysis: 2 zones on the left image and 
2 zones on the right. On both images pair of zones has an 
identical position relative to the course and some shift along the 
angle of elevation. The vertical size of each zone makes about 
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