A system for high accuracy calibration of a scanning system, which provides an object for calibration of a known geometry, such as a plane or a sphere. Upon that object is marked a pattern of points or geometric shapes, such as a set of equilateral triangles or their vertices. A set of computer programmed elements process photographic images of the object (containing a depiction of the pattern of geometric objects) and scanned images of the object to calibrate to high precision parameters, including a focal point relationship value for scanning systems which use a camera as an image collector (which describes the relationships between the focal point of the lens and the light/image collection device of the camera), a set of values to correct for distortion of the lens, the relative distance between the image collector and the scanner light source and also an initial angle to determine light position scanning. The known geometric constraints of the object allow the location of the object to be determined by photographic images. By scanning the object and computing 3D X,Y,Z coordinates for those points against a constraint that the X,Y,Z coordinates fit onto the surface of the object, the system calibrates parameters pertaining to the relative distances between the image collector and light source, an initial angle of rotation for systems which employ movable light sources and other parameters. The system is applied to multiple camera scanning systems to calibrate rotation matrices and translation vectors which facilitate the joining of the scanned data. The system further facilitates the design of flexible and movable scanning systems, such as portable scanners.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of the filing date, under 35 U.S.C. .sctn. 120, of pending commonly-owned U.S. patent application Ser. No. 08/620,689, filed on Mar. 21, 1996, which is expressly incorporated by reference herein. This application is also related to commonly-owned U.S. application entitled "Portable 3-D Scanning System and Method For Rapid Shape Digitizing and Adaptive Mesh Generation," filed on even date herewith, which is expressly incorporated by reference herein.
Embodiments of the invention relate to a method for minimizing the influence of disturbing signals during calculation of shape elements from coordinate points. An aim of the embodiments of the invention is to exclude the coordinates which are not to be locally assigned to the desired shaped element from the calculation of the shaped element. Said aim is achieved by combining compensation methods for calculating the desired type of shaped element with recognition methods for the same type of shaped element and using the recognition methods for filtering the coordinate points that are relevant for calculating the shaped element out of all input coordinate points.
Embodiments of the invention relate to a method for minimizing the influence of disturbing signals during calculation of shape elements from coordinate points. An aim of the embodiments of the invention is to exclude the coordinates which are not to be locally assigned to the desired shaped element from the calculation of the shaped element. This aim is achieved by combining compensation methods for calculating the desired type of shaped element with recognition methods for the same type of shaped element and using the recognition methods for filtering the coordinate points that are relevant for calculating the shaped element out of all input coordinate points.
The invention provides a camera calibration apparatus which eliminates the necessity to effect mapping making a distinction among a plurality of characteristic points and can prevent complication in mapping processing even if the number of characteristic points increases. An object imaging section images a sphere whose magnitude and position in a three-dimensional coordinate system are known, and a magnitude/position detection section determines a magnitude and a position of the sphere on a screen from an image imaged by the object imaging section. A center position estimation section estimates a three-dimensional position of the center of the sphere from the magnitude and the position of the sphere on the screen determined by the magnitude/position detection section, and a parameter calculation section calculates a position of the object imaging section in the three-dimensional coordinate system based on the three-dimensional position of the center of the sphere estimated by the center position estimation section.
The invention provides a camera calibration apparatus which eliminates the necessity to effect mapping making a distinction among a plurality of characteristic points and can prevent complication in mapping processing even if the number of characteristic points increases. An object imaging section images a sphere whose magnitude and position in a three-dimensional coordinate system are known, and a magnitude/position detection section determines a magnitude and a position of the sphere on a screen from an image imaged by the object imaging section. A center position estimation section estimates a three-dimensional position of the center of the sphere from the magnitude and the position of the sphere on the screen determined by the magnitude/position detection section, and a parameter calculation section calculates a position of the object imaging section in the three-dimensional coordinate system based on the three-dimensional position of the center of the sphere estimated by the center position estimation section.
A method in accordance with our invention permits the manipulation of a two-dimensional pixel array using a standard 3D graphics pipeline. The method comprises the steps of forming a wire mesh of the two-dimensional image. This wire mesh comprises a set of triangles, in which all of the vertices and sides of the triangles are located in the same plane in x, y, z coordinate space. The 2D image is then mapped into the mesh. The resulting object representation can then be manipulated in the same manner that 3D representations are manipulated by a 3D graphics pipeline.
