Generally, a vehicle includes a side-view mirror and a rear-view mirror in order to enable a driver to confirm circumstances around the vehicle. However, there exists a blind area (i.e. an area out of driver's vision) where the driver may not see from a driver seat even by using the side-mirror or the rear-view mirror because of a structure of the vehicle. In order to minimize the blind area, there exists a vehicle that includes an additional mirror at a vehicle body (e.g. in the vicinity of a hood (bonnet) or in the vicinity of a rear gate). However, even by using such mirror provided at the vehicle body, it is not easy to clear the blind area completely. Furthermore, in the case where such mirror is provided at the vehicle body, a design of the vehicle may be deteriorated. Hence, a technology of enabling the driver to confirm the circumstances around the vehicle by using a capture image obtained by a camera and the like provided at the vehicle is suggested (e.g. “Around View Monitor”, Technological Development Activities, NISSAN, http://www.nissan-global.com/EN/TECHNOLOGY/INTRODUCTION/DETAILS/AVM/, and “Multi-view Camera System”, Press Information 2008, HONDA, Sep. 18, 2008, http://www.honda.co.jp/news/2008/4080918b.html).
According to the Around View Monitor of Nissan and the Multi-view Camera System of Honda, for example, in a case where the vehicle is rearwardly moved, a capture image capturing a rear view of the vehicle and a bird-eye image capturing areas around the vehicle are shown side-by-side in a right-and-left direction on a monitor provided at the vehicle. The bird-eye image is generated on the basis of capture images obtained by means of respective four cameras, which are provided at the vehicle.
According to the Around View Monitor of Nissan and the Multi-view Camera System of Honda, the bird-eye view is generated on the basis of the capture images captured by the respective four cameras. Therefore, a solid object included in the bird-eye image may be displayed as if the solid object is radially stretched with reference to a position of the camera capturing the image including the solid object. In other words, the solid object may be shown unnaturally on the bird-eye image. Furthermore, because the solid object is shown as if being radially stretched on the bird-eye image, a user may mistakenly perceive the solid object on the bird-eye image as an image drawn on a road surface. Therefore, the vehicle may contact the solid object if the driver does not perceive the solid object correctly. Additionally, according to the Around View Monitor of Nissan and the Multi-view Camera System of Honda, the capture images obtained by the respective four cameras are separately and independently shown on the monitor. Therefore, if an object exists at a border between the neighboring capture images, the object may not be shown on the monitor, which may confuse the user. Accordingly, a vehicle surroundings monitoring system and a method for adjusting the same disclosed in JP2003-204547A, a vehicle rear monitoring system and a monitoring device disclosed in JP 3916958B, and an image displaying device for a vehicle disclosed in JP2003-346189A are suggested.
The vehicle surroundings monitoring system disclosed in JP2003-204547A includes eight cameras at a vehicle. The vehicle surroundings monitoring system generates a bird-eye view covering the entire circumference of the vehicle on the basis of capture images obtained by the respective eight cameras. The cameras are provided at the vehicle so as to keep an angle, so that the solid object is shown to extend in the same direction at the border portion on the capture images in order to include a solid object, which exists at the border between covering areas of the neighboring cameras so as to vertically stand at the border, on the bird-eye image.
The vehicle rear monitoring system and the monitoring device disclosed in JP3916958B includes a rear-view camera for capturing a rear-view of the vehicle, and side-view cameras provided at right and left sides of the vehicle, respectively. The vehicle rear monitoring system generates a high angle image on the basis of a capture image captured by the rear-view camera. Then, the generated high angle image is combined with capture images obtained by the side-view cameras, thereby generating one image to be displayed on a monitor provided at the vehicle.
The image displaying device for the vehicle disclosed in JP2003-346189A is configured with plural cameras, which are provided at the vehicle. The image displaying device for the vehicle generates a projected image on the basis of capture images obtained by the respective cameras, so that the image on which the vehicle is projected from a viewpoint above the vehicle is created. Then, a graphic data, which describes the vehicle from a viewpoint above the vehicle, is superimposed on the generated projected image.
The vehicle surroundings monitoring system disclosed in JP2003-204547 may reduce a possibility of the solid object existing on the border between the neighboring camera covering areas being missed on the bird-eye image. However, because eight cameras are used for the vehicle surrounding monitoring system even though the bird-eye image covering all circumferences of the vehicle is sufficiently generated by four cameras, manufacturing costs of the vehicle surroundings monitoring system may increase. Furthermore, the solid object may still be shown as if being unnaturally stretched on the bird-eye view. Therefore, the user may mistakenly perceive the solid object shown on the bird-eye image as the image drawn on the road surface. Accordingly, the vehicle may contact the solid object if the driver does not perceive the solid object correctly.
According to the vehicle rear monitoring system disclosed in JP3916958B, each of the side-view cameras captures the side view as a view reflected on the side-view mirror, so that a lower portion of the high angle image displays a distant area. Therefore, in a case where the user shifts his/her attention from the high angle image to the images captured by the respective side-view cameras, the user may be confused because a moving direction of the vehicle is shown differently on the high angle image and the images captured by the respective side-view cameras. Furthermore, each of the side-view cameras is provided at the vehicle so as to face rearward of the vehicle. Therefore, in order to display front-end lateral portions of the vehicle, an additional side-view camera needs to be provided at each of the right and left sides of the vehicle, which may result in increasing the manufacturing costs.
The reference of JP2003-346189A discloses that the image displaying device for the vehicle displays the image viewed from above the vehicle. However, the reference of JP2003-346189A does not indicate or mention a method of displaying the image viewed from above the vehicle in detail.
According to the Around View Monitor of Nissan and the Multi-view Camera System of Honda, the rear view of the vehicle captured by the camera and the bird-eye image are displayed on the display side-by-side when the vehicle moves backward. A distant view in a moving direction of the vehicle is shown at an upper portion on the rear-view image. On the other hand, the distant view in the moving direction of the vehicle is shown at a lower portion on the bird-eye image. Therefore, because the moving direction of the vehicle is shown differently on the rear-view image and the bird-eye image, the user may be confused. As a result, the user may refer only to (look at) either the rear-view image or the bird-eye image.
A need thus exists to provide a surroundings monitoring device for a vehicle which is not susceptible to the drawback mentioned above.