Imaging system and method with ego motion detection
An imaging system and method for a vehicle is provided, and includes an imager configured to image a scene external and forward of the vehicle and to generate image data corresponding to the acquired images. A controller is configured to receive the image data and analyze an optical flow between successive image frames to compute a relative motion between the imager and the imaged scene, wherein the optical flow includes a pattern of apparent motion of objects of interest in the successive image frames.
1. An imaging system for a vehicle, comprising:
an imager configured to acquire one or more images of a scene external and forward of the vehicle and to generate image data corresponding to the one or more acquired images; and
a controller configured to:
analyze the image data to detect objects of interest in successive image frames, wherein each object of interest comprises one of a moving object and a stationary object;
compute a first value based on a change in position for each object of interest appearing in the successive image frames;
compute a second value based on a change in position for only the objects of interest appearing in the successive image frames as having a common apparent motion, wherein moving objects are excluded from the computation of the second value; and
determine a relative motion between the imager and the scene based on the first and second values.
2. The imaging system of claim 1 , wherein the controller computes the first value by averaging the positions of objects of interest in each image frame and taking the difference between the averages determined for each image frame.
3. The imaging system of claim 1 , wherein the controller computes the second value by summing the changes in position of only the objects of interest appearing in the successive images as having the common apparent motion and averaging the sums.
4. The imaging system of claim 1 , wherein the controller determines the relative motion by taking a weighted average of the first and second values.
5. The imaging system of claim 1 , wherein the change in position comprises a change in vertical position and the common apparent motion is in a vertical direction.
6. The imaging system of claim 1 , wherein the controller is further configured to compute a heading of the vehicle by transforming a yaw signal to an image domain, and wherein the relative motion is further based on a time average of the heading.
7. The imaging system of claim 1 , wherein based on the determined relative motion, the controller corrects apparent motion of objects of interest caused by ego motion of the imager.
8. The imaging system of claim 1 , integrated in a rearview mirror assembly of the vehicle.
9. An imaging system for a vehicle, comprising:
an imager configured to acquire one or more images of a scene external and forward of the vehicle and to generate image data corresponding to the one or more acquired images; and
a controller configured to:
analyze the image data to detect objects of interest in successive image frames, wherein each object of interest comprises one of a moving object and a stationary object;
compute a first value corresponding to a total average change in position for all objects of interest appearing in the successive image frames;
compute a second value corresponding to a total average sum of changes in position for only the objects of interest appearing in the successive images as having a common apparent motion, wherein moving objects are excluded from the computation of the second value; and
determine a relative motion between the imager and the scene based on the first and second values.
10. The imaging system of claim 9 , wherein the controller determines the relative motion by taking a weighted average of the first and second values.
11. The imaging system of claim 9 , wherein the change in position comprises a change in vertical position and the common apparent motion is in a vertical direction.
12. The imaging system of claim 9 , wherein the controller is further configured to compute a heading of the vehicle by transforming a yaw signal to an image domain, and wherein the relative motion is further based on a time average of the heading.
13. The imaging system of claim 9 , wherein based on the determined relative motion, the controller corrects apparent motion of objects of interest caused by ego motion of the imager.
14. The imaging system of claim 9 , integrated in a rearview mirror assembly of the vehicle.
15. A non-transitory computer-readable medium having stored thereon software instructions that, when executed by a processor, comprise the steps of:
acquiring one or more images of a scene external and forward of a vehicle and generating image data corresponding to the one or more acquired images;
analyzing the image data to detect objects of interest in successive image frames, wherein each object of interest comprises one of a moving object and a stationary object;
computing a first value based on a change in position for each object of interest appearing in the successive image frames;
computing a second value based on a change in position for only the objects of interest appearing in the successive image frames as having a common apparent motion, wherein moving objects are excluded from the computation of the second value; and
determining a relative motion between the imager and the scene based on the first and second values.
16. The non-transitory computer-readable medium of claim 15 , wherein the step of computing the first value comprises averaging the positions of objects of interest in each image frame and taking the difference between the averages determined for each image frame.
17. The non-transitory computer-readable medium of claim 15 , wherein the step of computing the second value comprises summing the changes in position of only the objects of interest appearing in the successive images as having the common apparent motion and averaging the sums.
18. The non-transitory computer-readable medium of claim 15 , further comprising the step of computing a heading of the vehicle by transforming a yaw signal to an image domain and taking a time average of the heading, wherein the relative motion is further based on the time averaged heading.
19. The non-transitory computer-readable medium of claim 15 , further comprising the step of correcting apparent motion of objects of interest caused by ego motion of the imager.
20. The non-transitory computer-readable medium of claim 15 , wherein the change in position comprises a change in vertical position and the common apparent motion is in a vertical direction.