| Operators |
gen_caltab — Generate a calibration plate description file and a corresponding PostScript file for a calibration plate with rectangularly arranged marks.
gen_caltab( : : XNum, YNum, MarkDist, DiameterRatio, CalPlateDescr, CalPlatePSFile : )
gen_caltab generates the description of a standard HALCON calibration plate with rectangularly arranged marks. This calibration plate consists of XNum times YNum black circular marks on a white plane which are surrounded by a black frame.
The marks are arranged in a rectangular grid with YNum and XNum equidistant rows and columns. The distances between these rows and columns defines the parameter MarkDist in meter. The marks' diameter can be set by the parameter DiameterRatio and is defined by the equation . Using a distance between marks of 0.01 m and a diameter ratio of 0.5, the width of the dark surrounding frame becomes 8 cm, and the radius of the marks is set to 2.5 mm. The coordinate system of the calibration plate is located in the barycenter of all marks, its z-axis points into the calibration plate, its x-axis to the right, and its y-axis downwards.
The black frame of the calibration plate encloses a triangular black orientation mark in the top left corner to uniquely determine the position of the calibration plate. The width and the height of the generated calibration plate can be calculated with the following equations:
The file CalPlateDescr contains the calibration plate description, e.g., the number of rows and columns of the calibration plate, the geometry of the surrounding frame (see find_caltab), the triangular orientation mark, an offset of the coordinate system to the plate's surface in z-direction, and the x,y coordinates and the radius of all calibration plate marks given in the calibration plate coordinate system. The definition of the orientation and the offset, indicated by t and z, is optional and can be commented out. The default HALCON file extension for the calibration plate description is 'descr'. A file generated by gen_caltab looks like the following (comments are marked by a '#' at the beginning of a line):
# Plate Description Version 2 # HALCON Version 7.1 -- Fri Jun 24 16:41:00 2005 # Description of the standard calibration plate # used for the camera calibration in HALCON # (generated by gen_caltab) # # # 7 rows x 7 columns # Width, height of the black frame [meter]: 0.1, 0.1 # Distance between mark centers [meter]: 0.0125 # Number of marks in y-dimension (rows) r 7 # Number of marks in x-dimension (columns) c 7 # offset of coordinate system in z-dimension [meter] (optional): z 0 # Rectangular border (rim and black frame) of calibration plate # rim of the calibration plate (min x, max y, max x, min y) [meter]: o -0.05125 0.05125 0.05125 -0.05125 # outer border of the black frame (min x, max y, max x, min y) [meter]: i -0.05 0.05 0.05 -0.05 # triangular corner mark given by two corner points (x,y, x,y) [meter] # (optional): t -0.05 -0.0375 -0.0375 -0.05 # width of the black frame [meter]: w 0.003125 # calibration marks: x y radius [meter] # calibration marks at y = -0.0375 m -0.0375 -0.0375 0.003125 -0.025 -0.0375 0.003125 -0.0125 -0.0375 0.003125 -3.46945e-018 -0.0375 0.003125 0.0125 -0.0375 0.003125 0.025 -0.0375 0.003125 0.0375 -0.0375 0.003125 # calibration marks at y = -0.025 m -0.0375 -0.025 0.003125 -0.025 -0.025 0.003125 -0.0125 -0.025 0.003125 -3.46945e-018 -0.025 0.003125 0.0125 -0.025 0.003125 0.025 -0.025 0.003125 0.0375 -0.025 0.003125 # calibration marks at y = -0.0125 m -0.0375 -0.0125 0.003125 -0.025 -0.0125 0.003125 -0.0125 -0.0125 0.003125 -3.46945e-018 -0.0125 0.003125 0.0125 -0.0125 0.003125 0.025 -0.0125 0.003125 0.0375 -0.0125 0.003125 # calibration marks at y = -3.46945e-018 m -0.0375 -3.46945e-018 0.003125 -0.025 -3.46945e-018 0.003125 -0.0125 -3.46945e-018 0.003125 -3.46945e-018 -3.46945e-018 0.003125 0.0125 -3.46945e-018 0.003125 0.025 -3.46945e-018 0.003125 0.0375 -3.46945e-018 0.003125 # calibration marks at y = 0.0125 m -0.0375 0.0125 0.003125 -0.025 0.0125 0.003125 -0.0125 0.0125 0.003125 -3.46945e-018 0.0125 0.003125 0.0125 0.0125 0.003125 0.025 0.0125 0.003125 0.0375 0.0125 0.003125 # calibration marks at y = 0.025 m -0.0375 0.025 0.003125 -0.025 0.025 0.003125 -0.0125 0.025 0.003125 -3.46945e-018 0.025 0.003125 0.0125 0.025 0.003125 0.025 0.025 0.003125 0.0375 0.025 0.003125 # calibration marks at y = 0.0375 m -0.0375 0.0375 0.003125 -0.025 0.0375 0.003125 -0.0125 0.0375 0.003125 -3.46945e-018 0.0375 0.003125 0.0125 0.0375 0.003125 0.025 0.0375 0.003125 0.0375 0.0375 0.003125The file CalPlatePSFile contains the corresponding PostScript description of the calibration plate.
Depending on the accuracy of the used output device (e.g., laser printer), the printed calibration plate may not match the values in the calibration plate description file CalPlateDescr exactly. Thus, the coordinates of the calibration marks in the calibration plate description file may have to be corrected!
Number of marks in x direction.
Default value: 7
Suggested values: 5, 7, 9
Recommended increment: 1
Restriction: XNum > 1
Number of marks in y direction.
Default value: 7
Suggested values: 5, 7, 9
Recommended increment: 1
Restriction: YNum > 1
Distance of the marks in meters.
Default value: 0.0125
Suggested values: 0.1, 0.0125, 0.00375, 0.00125
Restriction: 0.0 < MarkDist
Ratio of the mark diameter to the mark distance.
Default value: 0.5
Suggested values: 0.5, 0.55, 0.6, 0.65
Restriction: 0.0 < DiameterRatio < 1.0
File name of the calibration plate description.
Default value: 'caltab.descr'
List of values: 'caltab.descr', 'caltab_100mm.descr', 'caltab_10mm.descr', 'caltab_200mm.descr', 'caltab_30mm.descr'
File extension: .descr
File name of the PostScript file.
Default value: 'caltab.ps'
File extension: .ps
* Create calibration plate with width = 80 cm. gen_caltab( 7, 7, 0.1, 0.5, 'caltab.descr', 'caltab.ps')
gen_caltab returns 2 (H_MSG_TRUE) if all parameter values are correct and both files have been written successfully. If necessary, an exception is raised.
find_caltab, find_marks_and_pose, camera_calibration, disp_caltab, sim_caltab
Foundation
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