find_caltab ( Image : Caltab : CalTabDescrFile, SizeGauss, MarkThresh : )

Segmentation of the calibration table region in the image.

find_caltab is used to determine the region of a plane calibration table with circular marks in the input image Image. This is done by first smoothing the input image (see gauss__); the size of the used filter mask is given by SizeGauss. Afterwards a thresholding operator (see threshold__) with minimum grey value MarkThresh and maximum grey value 255 is applied. The result of find_caltab is the most convex region with the correct number of holes among all the remaining regions. The correct number of holes corresponds to the number of marks on the calibration table and is read from the calibration table description file CalTabDescrFile. The complete explanation of this file can be found by the description of create_caltab.


Parameters

Image (input_object)
image -> object : byte
Input image.

Caltab (output_object)
region -> object
Output region.

CalTabDescrFile (input_control)
string -> string
File name of the calibration table description.
Default value: 'caltab.descr'

SizeGauss (input_control)
integer -> integer
Filter size of the Gaussian.
Default value: 3
List of values: 3, 5, 7, 9, 11, 13

MarkThresh (input_control)
integer -> integer
Threshold value for mark extraction.
Default value: 112
List of values: 48, 64, 80, 96, 112, 128, 144, 160


Example
/* read calibration image */
read_image(:Image:'calib-01.tiff':) >
/* find calibration pattern */
find_caltab(Image:Caltab:'caltab.descr',3,112:).

Result

find_caltab returns TRUE if all parameter values are correct and a image region is found. The behavior in case of empty input (no image given) can be set via set_system(::'no_object_result',<Result>:) and the behavior in case of an empty result region via set_system(::'store_empty_region',<true/false>:). If necessary an exception is raised.


Possible Predecessors

read_image


Possible Successors

find_marks_and_pose


See also

find_marks_and_pose, camera_calibration, disp_caltab, sim_caltab, caltab_points, create_caltab



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