Methods and computer program products for calibrating stereo imaging systems by using a planar mirror

A non-transitory computer program product, which includes computer-readable instructions that, when running on a computer, carry out a method comprising:

• obtaining an image captured by at least one camera, the image comprising a first picture of a real view of an object, a second picture of a mirror view of the object, and a third picture of a mirror view of a camera;
• finding a center of the mirror view of the at least one camera comprised in the third picture;
• determining a relative focal length defined for the at least one camera;
• determining an aspect ratio associated with an image based at least on the relative focal length defined for the at least one camera and the center of the mirror view of the at least one camera;
• determining a mirror plane equation in a coordinate system of the at least one camera based on the aspect ratio associated with the image captured and the relative focal length defined for the at least one camera;
• and
• determining a coordinate transformation between the coordinate system of the at least one camera and a mirror coordinate system having an origin in a mirror plane.

A method for calibrating a stereo imaging system comprising:

• obtaining at least two images, a first image of the at least two images comprising a first picture of mirror view of at least one camera and a second picture of a mirror view of an object, and a second image of the at least two images comprising a third picture of a mirror view of the at least one camera and a fourth picture of a mirror view of the object;
• identifying a center of the mirror view of the at least one camera comprised in the first picture;
• identifying a center of the mirror view of the at least one camera comprised in the third picture;
• determining a relative focal length defined for the at least one camera,
• determining an aspect ratio associated with the first image of the at least two images based at least on the relative focal length defined for the at least one camera
• determining an aspect ratio associated with the second image of the at least two images based at least on the relative focal length defined for the at least one camera;
• determining a mirror plane equation in the coordinate system of the at least one camera based at least on the aspect ratio associated with the first image and the center of the mirror view of the at least one camera comprised in the first picture;
• determining a mirror plane equation in the coordinate system of the at least one camera based at least on the aspect ratio associated with the second image and the center of the mirror view of the at least one camera comprised in the third picture;
• defining an up-vector in a mirror's plane;
• identifying, in the mirror's plane, a reference point that is an origin in the coordinate system of the mirror,
• determining a first coordinate transformation from a coordinate system of the at least one camera and the coordinate system of the mirror for the first image of the at least two images;
• determining a second coordinate transformation from a coordinate system of the at least one camera and the coordinate system of the mirror for the second image of the at least two images;
• and
• determining a third coordinate transformation from a coordinate system of the first image of the at least two images and a coordinate system of the second image of the at least two images.

A method for calibrating a stereo image system comprising:

• obtaining an image captured by at least one camera, the image comprising a first picture of a real view of an object, a second picture of a mirror view of the object, and a third picture of a mirror view of a camera;
• finding a center of the mirror view of the at least one camera comprised in the third picture;
• determining a relative focal length defined for the at least one camera;
• determining an aspect ratio associated with an image based at least on the relative focal length defined for the at least one camera and the center of the mirror view of the at least one camera;
• determining a mirror plane equation in a coordinate system of the at least one camera based on the aspect ratio associated with the image captured and the relative focal length defined for the at least one camera;
• and
• determining a coordinate transformation between the coordinate system of the at least one camera and a mirror coordinate system having an origin in a mirror plane.