Exterior environment recognition device and exterior environment recognition method

1. An exterior environment recognition device comprising:

an image obtaining unit for sequentially obtaining a first image and a second image that are generated by alternately performing capture in a first exposure mode according to a level of light of an exterior environment and capture in a second exposure mode of which exposure time is different from the first exposure mode and which allows determination as to whether a light emitting source is emitting light by itself or not;

a vehicle identifying unit for identifying, based on the first image, a vehicle area occupied by a vehicle preceding in a detection area;

a light emitting source identifying unit for identifying a position of the light emitting source, based on luminance of the second image; and

a position associating unit for associating the position of the light emitting source and the vehicle area.

2. The exterior environment recognition device according to claim 1 , wherein the light emitting source identifying unit groups, on the basis of a relative distance between pixels which are adopted as candidates of a light emitting source, multiple pixels into one light emitting source candidate, and only when a size of the light emitting source candidate is equal to or more than a first threshold value defined in advance, the light emitting source candidate is identified as the light emitting source.

3. The exterior environment recognition device according to claim 2 , wherein multiple first threshold values are provided in advance at multiple steps in accordance with the level of light of the exterior environment.

4. The exterior environment recognition device according to claim 1 , further comprising an arrangement determining unit which determines whether relative arrangement of the position of the light emitting source and the vehicle area associated by the position associating unit is appropriate arrangement or not.

5. The exterior environment recognition device according to claim 4 , wherein:

the light emitting source includes a brake lamp and a high mount stop lamp,

the light emitting source identifying unit groups, on the basis of a relative distance between pixels which are adopted as candidates of a light emitting source, multiple pixels into one light emitting source candidate, and only when a size of the light emitting source candidate is equal to or more than a third threshold value defined in advance, the light emitting source candidate is identified as the high mount stop lamp,

when the light emitting source candidate is identified as the high mount stop lamp, the arrangement determining unit recognizes the vehicle area is a vehicle that has a high mount stop lamp, and

when it is determined that a brake lamp is turned on but the high mount stop lamp is not detected, the arrangement determining unit determines that the brake lamp is not turned on.

6. The exterior environment recognition device according to claim 1 , wherein the light emitting source is at least one of a brake lamp, a high mount stop lamp, a tail lamp, and a turn signal.

7. The exterior environment recognition device according to claim 1 , wherein:

the light emitting source includes a brake lamp and a tail lamp, and

the exterior environment recognition device further includes a brake lamp identifying unit for identifying the position of the brake lamp, on the basis of relationship in terms of luminance between the brake lamp and the tail lamp and the position of the tail lamp.

8. The exterior environment recognition device according to claim 7 , wherein:

the light emitting source includes a brake lamp and a tail lamp, and

the brake lamp identifying unit detects the position of the tail lamp by identifying a portion, where an R component is high and a luminance value is high, and, based on the information on the tail lamp, determines that brake lamp is turned on when there is increase in the luminance value of the position of the tail lamp in the second image.

9. An exterior environment recognition method comprising:

a step in which an imaging device alternately performs capture in a first exposure mode according to a level of light of an exterior environment and capture in a second exposure mode of which exposure time is different from the first exposure mode and which allows determination as to whether a light emitting source is emitting light by itself or not;

a step in which an exterior environment recognition device sequentially obtains a first image captured in the first exposure mode and a second image captured in the second exposure mode;

a step in which a vehicle area occupied by a vehicle preceding in a detection area is identified based on the first image;

a step in which a position of the light emitting source is identified based on luminance of the second image; and

a step in which the position of the light emitting source and the vehicle area are associated.