System and method for automated test-pattern-free projection calibration
First Claim
1. A method to correct for rotational distortions of an image projected from an image projector on a viewing surface without using a test pattern, said method comprising:
- acquiring an image of a scene containing the viewing surface, using at least one image capture device equipped with an Ultra Wide-Angle (UWA) lens with a field of view of about 180°
or larger and having a lens mapping transformation, with a known orientation relative to the image projector;
using at least one image processing unit to;
identify at least a first pair of parallel lines in the image in the UWA lens space;
identify at least a second pair of parallel lines, orthogonal to the at least first pair of parallel lines, in the image in the UWA lens space;
obtain coordinates of vanishing points corresponding to the at least first and the at least second pair of parallel lines;
compute angles of rotation of the at least one image capture device with respect to a frame of reference, using the coordinates of the vanishing points;
construct a correction transformation using the rotational angles and the orientation of the at least one image capture device relative to the image projector;
wherein the correction transformation for the rotational angles is independent of a position of lens used to capture the image, andapply the correction transformation to correct for the rotational distortion of the image, wherein the correction transformation does not use a test pattern for correction.
10 Assignments
0 Petitions
Accused Products
Abstract
Systems and methods for calibrating an image projection system, using image capture devices are disclosed. In particular, Wide-Angle (WA) and Ultra Wide-Angle (UWA) lenses can be utilized to eliminate need for traditional test patterns and tedious alignment settings. That is particularly useful for automatic calibration of projection sources that may require frequent adjustments on the field. Geometric mapping techniques combined with image analytics allow identifying parallel lines in an image captured from a scene. Coordinates of vanishing points corresponding to pairs of parallel lines provide sufficient information to determine orientation of the image projection system in space.
-
Citations
22 Claims
-
1. A method to correct for rotational distortions of an image projected from an image projector on a viewing surface without using a test pattern, said method comprising:
-
acquiring an image of a scene containing the viewing surface, using at least one image capture device equipped with an Ultra Wide-Angle (UWA) lens with a field of view of about 180°
or larger and having a lens mapping transformation, with a known orientation relative to the image projector;using at least one image processing unit to; identify at least a first pair of parallel lines in the image in the UWA lens space; identify at least a second pair of parallel lines, orthogonal to the at least first pair of parallel lines, in the image in the UWA lens space; obtain coordinates of vanishing points corresponding to the at least first and the at least second pair of parallel lines; compute angles of rotation of the at least one image capture device with respect to a frame of reference, using the coordinates of the vanishing points; construct a correction transformation using the rotational angles and the orientation of the at least one image capture device relative to the image projector;
wherein the correction transformation for the rotational angles is independent of a position of lens used to capture the image, andapply the correction transformation to correct for the rotational distortion of the image, wherein the correction transformation does not use a test pattern for correction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A calibration system for use with an image projection set-up having an image source and a viewing surface, said system comprising:
-
at least one image capture device equipped with an Ultra Wide-Angle (UWA) lens with a field of view of about 180°
or larger and having a corresponding lens transformation, with a known orientation relative to the image projector, to acquire an image of a scene; and
at least one image processing unit to;detect a plurality of objects in the image that are presumed vertical and horizontal objects in the scene; identify at least a first pair of parallel lines in one or more of the plurality of the horizontal objects, and least a second pair of parallel lines orthogonal to the at least first pair of parallel lines in one or more of the plurality of the vertical objects, in the image in the UWA lens space; obtain coordinates of vanishing points corresponding to the at least first and the at least second pair of parallel lines; compute rotational angles of the image capture device with respect to a frame of reference, using the coordinates of the vanishing points; and construct a correction transformation using the rotational angles and the orientation of the at least one image capture device relative to the image projector; and apply the correction transformation to correct for the rotational distortion of the acquired image. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
-
-
22. A calibration method for use with an image projection set-up having an image source and a viewing surface, said method being carried out by at least one electronic processor configured to:
-
receive input image data acquired, from a scene containing the viewing surface, by at least one image capture device equipped with an Ultra Wide-Angle (UWA) lens with a field of view of about 180°
or larger and having a corresponding lens transformation;receive input data representing orientation of the at least one image capture device relative to the image projector; detect a plurality of objects in the image that are presumed vertical and horizontal objects in the scene; identify at least a first pair of parallel lines in one or more of the plurality of the horizontal objects, in the image in the UWA lens space; identify at least a second pair of parallel lines, in one or more of the plurality of the vertical objects in the image in the UWA lens space; compute coordinates of vanishing points corresponding to the at least first and the at least second pair of parallel lines; compute angles of rotation of the at least one image capture device with respect to a frame of reference, using the coordinates of the vanishing points; construct a correction transformation using the computed angles of rotation and the orientation of the at least one image capture device relative to the image projector; and store data corresponding to a corrected image based on the correction information to a memory device.
-
Specification