README
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- CAMERA CALIBRATION TOOLBOX FOR MATLAB (v2.1b)
- Installation
- ------------
- Simply copy all the .m files into a directory 'calibr' and add it to your
- MATLABPATH. Matlab version 4.0 or later is required.
- Things to do
- ------------
- If you have a 3-D calibration object, you can cope with a single image. In
- order to obtain satisfactory calibration result, the object should cover the
- entire image as well as possible. Also, multiple images are supported. Then,
- the images should be captured from different viewpoints changing the camera
- orientation and distance. In case of a coplanar calibration target a single
- image is not adequate and a set of images (2-6) is needed to solve all
- the camera parameters. The coordinates of the coplanar control points should
- be selected so that the z coordinates become zero. The 3-D coordinate unit is
- millimeter and image coordinate unit is pixel. The calibration coordinate
- system is right-handed. The origin of the image coordinate system is in the
- top left corner, x axis is to the right and y axis downwards.
- The input data to CACAL-routine is following:
- First parameter is a string that defines the camera type. The valid camera
- types are listed in CONFIGC.M that is a function where the user can add his
- own configuration data. The data consists of the following information:
- NDX number of pixels in horizontal direction
- NDY number of pixels in vertical direction
- Sx effective CCD chip size in horizontal direction [mm]
- Sy effective CCD chip size in vertical direction [mm]
- f0 nominal focal length (needed in case of coplanar targets)
- rad radius of the control points [mm] (needed in circal)
- name name of the setup
- The calibration data is given in separate matrices for each image. The maximum
- number of images is currently six. The data matrix structure is following:
- Columns 1 to 3: x, y, and z coordinates of the control points. In case of a
- a coplanar target the z-coordinates must be zero.
- Columns 4 to 5: corresponding x- and y- image coordinates.
- Columns 6 to 8: normal vector [nx ny nz] of the target surface around
- the control point given in the world coordinate frame.
- The output data is following:
- - Eight intrinsic camera parameters:
- par(1)=scale factor ~1
- par(2)=effective focal length
- par(3:4)=principal point
- par(5:6)=radial distortion coefficients
- par(7:8)=tangential distortion coefficients
- - The position and orientation of the camera for each image:
- pos(1:3)=x, y, z -coordinates (actually, the position
- of the calibration coordinate frame origin with
- respect to the camera coordinate frame)
- pos(4:6)=w, p, r euler rotation angles around x, y, z axes.
- - Number of iterations required
- - Sum of squared error terms
- - The remaining error in pixels. This error gives a guideline to detect
- the accuracy of the calibration. The error should be non-systematic with
- the standard deviation less than 0.2 pixels. If the error is larger,
- something goes wrong.
- - Covariance matrix of the estimated parameters. The diagonal elements gives
- the variance of the estimates.
-
-
- For more information, see:
- Heikkila, J. & Silven O. (1996) Calibration procedure for short focal
- length off-the-shelf CCD cameras. In: Proc of The 13th International
- Conference on Pattern Recognition. Vienna, Austria. pp. 166-170.
-
- Heikkil