Stereo calibration apparatus and stereo image monitoring apparatus using the same

• US 20040234124A1
• Filed: 03/12/2004
• Published: 11/25/2004
• Est. Priority Date: 03/13/2003
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nakai, Hiroaki, Maruyama, Masayuki, Putthividhya, Duangmanee
• Granted Patent: US 7,313,265 B2
• Time in Patent Office: Days
• US Class Current: 382/154
• CPC Class Codes: G06T 7/564 from contours
• CPC Class Codes: G06T 7/593 from stereo images
• CPC Class Codes: G06T 7/85 Stereo camera calibration

Abstract

The stereo calibration apparatus includes an image input device inputting an image from each of two image pickup devices, a straight-line detector detecting at least four straight lines from each of two input images, a straight-line correspondence detector detecting at least four sets of corresponding lines by using an image feature in a neighboring area of the straight line, and a transformation matrix calculator calculating a transformation matrix between two image pickup devices from the sets of corresponding lines.

Claims

1. A stereo calibration apparatus for obtaining a transformation matrix, which is an image transformation parameter between a pair of image pickup devices for photographing a preset common area, the stereo calibration apparatus comprising:

an image input device to which a pair of images is input from the one pair of image pickup devices;

a straight-line detector detecting at least four straight lines from each of images output from the image input device;

a straight-line correspondence detector detecting at least four sets of corresponding lines between the images by using an image feature in neighboring areas of the straight lines; and

a transformation matrix calculator calculating the transformation matrix by using the sets of corresponding lines.

2. The stereo calibration apparatus according to claim 1, wherein the straight-line correspondence detector performs area matching by using the image feature in the neighboring areas of the straight lines to detect the sets of corresponding lines.

3. The stereo calibration apparatus according to claim 1, wherein:

the straight-line correspondence detector obtains data series regarding the image feature from the neighboring area of each straight line,

obtains a normalized distance between the data series for each straight line detected from one of the images and the data series for each straight line detected from the other of the images, and

obtains the sets of corresponding straight lines sets in such a manner that one straight line in the other of the images, which has the minimum normalized distance with respect to one straight line in the one of the images, is set as a corresponding line to the one straight line in the one of the images.

4. The stereo calibration apparatus according to claim 1, wherein the transformation matrix calculator calculates the transformation matrix in accordance with a linear expression by using the sets of corresponding lines and a projective transformation expression regarding the straight lines.

5. A stereo calibration method for obtaining a transformation matrix, which is an image transformation parameter between a pair of image pickup devices for photographing a preset common area, the method comprising:

inputting a pair of images from the image pickup devices;

detecting at least four straight lines from each of input images;

detecting at least four sets of corresponding lines between the images by using an image feature in neighboring areas of the straight lines; and

calculating the transformation matrix between the image pickup devices by using the sets of corresponding lines.

6. A program which is executed by a computer to perform a process for obtaining a transformation matrix, which is an image transformation parameter between a pair of image pickup devices for photographing a preset common area, the process comprising:

inputting a pair of images from the image pickup devices;

detecting at least four straight lines from each of input images;

detecting at least four sets of corresponding lines between the images by using an image feature in neighboring areas of the straight lines; and

calculating the transformation matrix between the image pickup devices by using the sets of corresponding lines.

7. A stereo image monitor for detecting an object, the stereo image monitor comprising:

a pair of image pickup devices configured to photograph images containing a common area;

a straight-line detector detecting at least four straight lines from each of the images;

a straight-line correspondence detector detecting at least four sets of corresponding lines between the images by using an image feature in neighboring areas of the straight lines;

a transformation matrix calculator calculating the transformation matrix by using the sets of corresponding lines; and

a monitor transforming one of the pair of images by using the transformation matrix to detect an object in the common area.

8. A stereo image monitoring method for monitoring a common area, which photographed by a pair of image pickup devices, the method comprising:

inputting a pair of images from the image pickup devices;

detecting at least four straight lines from each of input images;

detecting at least four sets of corresponding lines between the images using an image feature in neighboring areas of the straight lines;

calculating a transformation matrix between the image pickup devices by using the sets of corresponding lines; and

transforming one of the pair of images by using the transformation matrix to detect an object in the common area.

9. A program which is executed by a computer to perform a process for monitoring a common area, which photographed by a pair of image pickup devices, the process comprising:

inputting a pair of images from the image pickup devices;

detecting at least four straight lines from each of input images;

detecting at least four sets of corresponding lines between the images by using an image feature in neighboring areas of the straight lines;

calculating a transformation matrix between the image pickup devices by using the sets of corresponding lines; and

transforming one of the pair of images by using the transformation matrix to detect an object in the common area

10. A stereo calibration apparatus for obtaining a transformation matrix, which is an image transformation parameter between a pair of image pickup devices for photographing a preset common area, the stereo calibration apparatus comprising:

an image input device to which a pair of images is input from the one pair of image pickup devices;

a straight-line detector detecting at least four straight lines from each of images output from the image input device;

a straight-line correspondence detector detecting at least four sets of corresponding lines between the images by using a geometrical relation among the straight lines; and

a transformation matrix calculator calculating the transformation matrix by using the sets of corresponding lines.

11. The stereo calibration apparatus according to claim 10, wherein the straight-line correspondence detector obtains the geometrical relation among the straight lines by using an intersection between one of the straight lines in each image and the others of the straight lines in each image.

12. The stereo calibration apparatus according to claim 10, wherein the straight-line correspondence detector uses an image feature in neighboring areas of the straight lines and the geometrical relation to obtain the sets of corresponding lines.

13. A stereo calibration method for obtaining a transformation matrix, which is an image transformation parameter between a pair of image pickup devices for photographing a preset common area, the method comprising:

inputting a pair of images from the image pickup devices;

detecting at least four straight lines from each of input images;

detecting at least four sets of corresponding lines between the images by using a geometrical relation among the straight lines; and

calculating the transformation matrix between the image pickup devices by using the sets of corresponding lines.

14. A program causing a computer to perform a process for obtaining a transformation matrix, which is an image transformation parameter between a pair of image pickup devices for photographing a preset common area, the process comprising:

inputting a pair of images from the image pickup devices;

detecting at least four straight lines from each of input images;

detecting at least four sets of corresponding lines between the images by using a geometrical relation among the straight lines; and

calculating the transformation matrix between the image pickup devices on by using the sets of corresponding lines.

15. A stereo image monitor for detecting an object, the stereo image monitor comprising:

a pair of image pickup devices configured to photograph images containing a common area;

an image input device to which a pair of images is input from the image pickup devices;

a straight-line detector detecting at least four straight lines from each of images output from the image input device;

a straight-line correspondence detector detecting at least four sets of corresponding lines between the images by using a geometrical relation among the straight lines;

a transformation matrix calculator calculating the transformation matrix by using the sets of corresponding lines; and

a monitor performing transforming one of the pair of images by using the transformation matrix to detect an object in the common area.

16. A stereo image monitoring method for monitoring a common area, which photographed by a pair of image pickup devices, the method comprising:

inputting a pair of images from the image pickup devices;

detecting at least four straight lines from each of input images;

obtaining at least four sets of corresponding lines between the images by using a geometrical relation among the straight lines;

calculating a transformation matrix between the image pickup devices by using the sets of corresponding lines; and

transforming one of the pair of images by using the transformation matrix to detect an object in the common area.

17. A program which is executed by a computer to perform a process for monitoring a common area, which photographed by a pair of image pickup devices, the process comprising:

inputting a pair of images from the image pickup devices;

detecting at least four straight lines from each of input images;

detecting at least four sets of corresponding lines between the images by using a geometrical relation among the straight lines;

calculating a transformation matrix between the image pickup devices by using the sets of corresponding lines; and

transforming one of the pair of images by using the transformation matrix to detect an object in the common area on the basis of a stereoscopic principle.