Television – Special applications – Observation of or from a specific location
Reexamination Certificate
1998-11-12
2002-10-15
Rao, Andy (Department: 2713)
Television
Special applications
Observation of or from a specific location
C348S149000
Reexamination Certificate
active
06466260
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a video-based traffic surveillance system and more particularly to a system for surveilling a traffic strategic point such as an intersection, pedestrian crossing or the like by using a television (TV) camera.
FIG. 13
shows a conventional surveillance system which aims to surveille traffic at an intersection and its neighboring area by using a TV image. On the TV system in this figure are shown conditions of typical installation near an intersection of the surveillance system. On the other hand,
FIG. 16
is a perspective view drawn from a photograph taken of an actual intersection and its neighboring area. Referring to the two figures, there are illustrated traffic signal lights proper
1
,
1
′N, traffic signal light posts
21
,
2
E,
2
W,
2
S and
2
N (E, W, S and N represent directions, respectively), a housing
33
of a surveillance TV camera
3
as depicted in
FIG. 14
, and a post
4
of the surveillance TV camera
3
. Denoted by
35
is a hold arm. The traffic signal lights are installed at east, west, south and north ends of the intersection in correspondence to passing directions of vehicles but for convenience of illustration, only bases of the posts
2
E,
2
W and
2
S are depicted for the traffic signal lights at the east, west and south ends.
In
FIG. 13
, buildings near the intersection, passing vehicles and pedestrians are omitted for convenience of illustration, too, and arrows on the road surface do not imply traffic regulation but indicate passing directions of vehicles.
The surveillance TV camera
3
is constructed as shown in FIG.
14
. More particularly, the TV camera proper
3
aiming at performing surveillance in all directions at the intersection is combined with a motor-driven zoom lens
31
to form a structure which is carried on a pan and tilt head
32
. To permit surveillance in all kinds of weather, the structure is contained in the camera housing
33
. Denoted by
34
is a carriage which is mounted to the hold arm
35
of the surveillance TV camera post
4
.
The surveillance TV camera
3
is mounted at a position which is determined by taking into account such points that as shown in
FIG. 16
, drivers in passing vehicles do not have difficulties in visually recognizing the traffic signal light proper, the view field of the TV camera is not disturbed by a nearby traffic signal light and the TV camera is allowed to have an unobstructed distant view.
FIG. 15
shows a typical example of an image obtained from the surveillance TV camera (corresponding to an image from the TV camera
3
installed near the traffic signal light
1
′N in FIG.
13
). In this example, the direction of the TV camera is so adjusted that the confrontal traffic signal light
1
S (not shown) can be viewed within the view field in order that the traffic flow near the intersection can be surveilled remotely. Further, when the image is recorded on a video tape recorder (VTR), not shown, the recorded image can be utilized to analyze causes of a traffic accident. But because of the aforementioned constraint imposed on the mount position, the TV camera is installed at only one corner, bringing about the following disadvantages.
(1) The pan and tilt head and the motor-driven zoom lens are used in combination to permit unobstructed views of all corners and as a result, the surveillance TV camera
3
and the housing
33
are increased in size. Accordingly, the surveillance TV camera post
4
needs to be highly rigid, leading to an increase in cost.
(2) In the example shown in
FIG. 13
in which the TV camera
3
is installed at the north end of the intersection, a view field in the south direction can be ensured as shown in
FIG. 15
but vehicles passing in the east and west directions are liable to be shaded by buildings and the traffic flow on this side lane. Especially, vehicles directly underneath and behind (northward) the surveillance TV camera
3
cannot at all be recognized.
(3) It fails to make traffic conditions in the all directions related to each other by having unobstructed views in the all directions at a time.
(4) When the TV camera manages to get a view of the confrontal traffic lights, it is difficult for the TV camera to ensure a view of an underneath area inside the intersection. If the traffic lights are viewed at an edge of the view field in order to get a wide view of the underneath area as illustrated in
FIG. 13
, the view field may sometimes deviate from the traffic lights in a heavily windy weather because both the camera and the traffic lights swing. Further, the view of the traffic lights is reduced in scale to make it difficult to discriminate colors.
In spite of the aforementioned disadvantages, the surveillance TV camera is installed at only one corner of the intersection. Presumably, this is because if TV cameras are installed at individual corners, the sidewalk will be jammed with not only illumination posts (not shown) and traffic signal light posts but also the surveillance TV camera posts and consequently the sidewalk area will be narrowed to disturb passage of pedestrians. In addition, the scenic beauty of city will be spoiled.
An example for elimination of the disadvantage in (2) above is available in which the surveillance camera post is installed closer to the intersection than the traffic signal light post and the arm
35
is extended up to the center of the intersection as shown in FIG.
16
. In this instance, however, the disadvantages in (1) and (4) above are conversely aggravated. In the example shown in
FIG. 16
, a structure is employed which permits a person to easily access the TV camera for the purpose of maintenance and in that case, both the post and the arm are required to be high in strength and are necessarily increased in size.
When an image of the surveillance TV camera is desired to be used, for multi-purpose, as a part of an advanced traffic control system, conditions of traffic flow in all directions at an intersection and its neighboring area must be grasped simultaneously from an optimal position. To this end, one solution is to install surveillance TV cameras at the individual corners. But if this is realized by installing the traffic signal light and the surveillance TV camera independently of each other as in the case of the prior art, disadvantages of the disturbance of passage of pedestrians and the spoilage of the scenic beauty of city will be actualized. Therefore, a method for camera installation which can eliminate these disadvantages is desired.
Conventionally, another system is available which automatically measures speed violation but as far as violation of traffic lights is concerned, the arrest of a flagrant offender by visual inspection prevails predominantly. In the arrest of a flagrant offender by visual inspection, it is necessary for a person who exposes a violator to always surveille the appearance of a violative vehicle by repeating such an operation as watching a light indication of a traffic signal light and then watching a predictive area in which the violative vehicle will appear. As will be seen from the above, the conventional system raises problems that the arrest of a violative vehicle is carried out by having resort to manual inspection to increase personnel expenses, all traffic signal lights cannot be surveilled, no evidence for traffic light violation is left behind, judgement during transition of a change of the traffic light tends to be obscure and determination of a violation area becomes obscure, thus making a judgement miss liable to occur. Further, in the conventional system in which the traffic signal light and the surveillance TV camera are installed independently of each other, the total of costs of installation of equipments tends to be comparatively high and traffic regulations practiced during installation work and maintenance/inspection have a great influence upon traffic.
Summary of the Invention
The present invention contemplates elimination of the conventional problems as above and it is an object of
Fujisaki Hitoshi
Hatae Yasuhiko
Kiyose Hisashi
Kuwahara Yuuichi
Antonelli Terry Stout & Kraus LLP
Hitachi Denshi Kabushiki Kaisha
Rao Andy
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