Stereo camera
View Patent ↗The present invention provides a stereo camera in which it is possible to improve the precision of correcting vertical offset between a first image captured by a first image-capture unit and a second image captured by a second image-capture unit. In the present invention, an image-capture system unit 100 a captures a benchmark image. An image-capture system unit 100 b captures a reference image. A geometry correction unit 125 generates a plurality of geometry-corrected reference images having differing amounts of vertical-direction movement from the reference image. A parallax calculation unit 126 generates a plurality of parallax images from the combination of the benchmark image and each of the reference images. A parallax image evaluation unit 131 calculates evaluation values pertaining to the reliability of each of the parallax images. A vertical offset correction unit 132 : calculates, on the basis of a correspondence relationship between vertical offset and the evaluation values pertaining to reliability, an evaluation value pertaining to the maximum reliability and a vertical offset that corresponds to this evaluation value; and sets the vertical offset that corresponds to the evaluation value pertaining to the maximum reliability as a vertical offset correction amount.
1. A stereo camera, comprising:
a first image-capture unit which captures a first image;
a second image-capture unit which captures a second image;
a geometry correction unit which generates a plurality of third images having a different moving amount in a vertical direction from the second image;
a parallax calculation unit which generates a plurality of parallax images from combinations of the first image and respective third images;
a parallax image evaluation unit which calculates a reliable degree of each parallax image; and
a vertical offset correction unit which calculates a maximum reliable degree and the moving amount corresponding to the maximum reliable degree on the basis of a correspondence relationship between the moving amount and the reliable degree, and sets the moving amount corresponding to the maximum reliable degree as a correction amount of a vertical offset.
2. The stereo camera according to claim 1 ,
wherein the geometry correction unit
corrects optical distortions of the first image and the second image,
and corrects the vertical offset between the first image and the second image using the correction amount of the vertical offset.
3. The stereo camera according to claim 2 , further comprising:
a storage unit which stores a mapping showing a correspondence relationship between the first image and the second image before and after a geometry correction,
wherein the geometry correction unit
corrects the optical distortions of the first image and the second image using the mapping, and
corrects the vertical offset between the first image and the second image using the correction amount of the vertical offset.
4. The stereo camera according to claim 1 ,
wherein at least the vertical offset correction unit
operates when the stereo camera is activated.
5. The stereo camera according to claim 3 ,
wherein the mapping
includes moving the second image in the vertical direction by the correction amount of the vertical offset, and
wherein the geometry correction unit
corrects the vertical offset between the first image and the second image using the mapping.
6. The stereo camera according to claim 1 ,
wherein the geometry correction unit and the parallax calculation unit are logical circuits.
7. The stereo camera according to claim 1 ,
wherein at least the vertical offset correction unit
operates in a case where an ambient temperature of the stereo camera is changed by equal to or more than a threshold within a predetermined time.
8. The stereo camera according to claim 1 ,
wherein at least the vertical offset correction unit
operates in a predetermined cycle.
9. The stereo camera according to claim 1 ,
wherein the reliable degree is an index indicating the number of valid parallax in each of the parallax image.
10. The stereo camera according to claim 9 ,
wherein the parallax calculation unit
calculates a similarity of a region of the first image and a region of the third image with respect to each of a plurality of combinations of the region of the first image and the region of the third image of the same height as the region of the first image, and calculates the parallax from the region of the first image and the region of the third image in which the similarity is maximized,
determines that the parallax is invalid in a case where the maximum similarity is less than a first threshold,
determines that the parallax is invalid in a case where there are two or more maximum values of the similarity, and a difference between a largest maximum value and a second largest maximum value is less than a second threshold,
determines that the parallax is valid in a case where the maximum similarity is equal to or more than the first threshold, and the number of maximum values of the similarity is only one, and
determines that the parallax is valid in a case where the maximum similarity is equal to or more than the first threshold, the number of maximum values of the similarity is equal to or more than two, and the difference between the largest maximum value and the second largest maximum value is equal to or more than the second threshold.