find_calib_objectT_find_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject (Operator)

Name

find_calib_objectT_find_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject — Find the standard calibration plate and set the extracted points and contours in a calibration data model.

Signature

Description

find_calib_objectfind_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject searches in ImageImageImageImageImageimage for a standard calibration plate corresponding to the description of the calibration object with the index CalibObjIdxCalibObjIdxCalibObjIdxCalibObjIdxCalibObjIdxcalibObjIdx from the calibration data model CalibDataIDCalibDataIDCalibDataIDCalibDataIDCalibDataIDcalibDataID. If a plate is found, find_calib_objectfind_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject extracts the centers and the contours of its marks and estimates the pose of the plate relative to the observing camera CameraIdxCameraIdxCameraIdxCameraIdxCameraIdxcameraIdx. Finally, all collected observation data are stored in the calibration data model for the calibration object pose CalibObjPoseIdxCalibObjPoseIdxCalibObjPoseIdxCalibObjPoseIdxCalibObjPoseIdxcalibObjPoseIdx.

find_calib_objectfind_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject is used to collect observations in a calibration data model (see set_calib_data_observ_pointsset_calib_data_observ_pointsSetCalibDataObservPointsset_calib_data_observ_pointsSetCalibDataObservPointsSetCalibDataObservPoints for description of calibration data observations) and it essentially encapsulates the sequence of three operator calls: find_caltabfind_caltabFindCaltabfind_caltabFindCaltabFindCaltab, find_marks_and_posefind_marks_and_poseFindMarksAndPosefind_marks_and_poseFindMarksAndPoseFindMarksAndPose and set_calib_data_observ_pointsset_calib_data_observ_pointsSetCalibDataObservPointsset_calib_data_observ_pointsSetCalibDataObservPointsSetCalibDataObservPoints. Besides encapsulating a great deal of parameter settings, it stores additional observation data compared to set_calib_data_observ_pointsset_calib_data_observ_pointsSetCalibDataObservPointsset_calib_data_observ_pointsSetCalibDataObservPointsSetCalibDataObservPoints, e.g., the calibration plate contour and the calibration marks' contours. Note that find_calib_objectfind_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject needs the full description of a standard calibration plate, i.e., a description file name must be passed to set_calib_data_calib_objectset_calib_data_calib_objectSetCalibDataCalibObjectset_calib_data_calib_objectSetCalibDataCalibObjectSetCalibDataCalibObject when specifying the CalibObjIdxCalibObjIdxCalibObjIdxCalibObjIdxCalibObjIdxcalibObjIdx-th calibration object. Otherwise, find_calib_objectfind_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject returns an error. Respectively, if a calibration object that is no standard calibration plate was specified by passing a tuple of mark coordinates to set_calib_data_calib_objectset_calib_data_calib_objectSetCalibDataCalibObjectset_calib_data_calib_objectSetCalibDataCalibObjectSetCalibDataCalibObject, only set_calib_data_observ_pointsset_calib_data_observ_pointsSetCalibDataObservPointsset_calib_data_observ_pointsSetCalibDataObservPointsSetCalibDataObservPoints can be used to collect observation data for the poses of this calibration object.

By setting GenParamNameGenParamNameGenParamNameGenParamNameGenParamNamegenParamName to one of the following values, the following additional parameters can be set in GenParamValueGenParamValueGenParamValueGenParamValueGenParamValuegenParamValue:

'gap_tolerance'"gap_tolerance""gap_tolerance""gap_tolerance""gap_tolerance""gap_tolerance":

Tolerance factor for gaps between the marks. If the marks appear closer to each other than expected, you might set 'gap_tolerance'"gap_tolerance""gap_tolerance""gap_tolerance""gap_tolerance""gap_tolerance" < 1.0 to avoid disturbing patterns outside the calibration plate to be associated with the calibration plate. This can typically happen if the plate is strongly tilted and positioned in front of a background that exposes mark-like patterns. If the distances between single marks vary in a wide range, e.g., if the calibration plate appears with strong perspective distortion in the image, you might set 'gap_tolerance'"gap_tolerance""gap_tolerance""gap_tolerance""gap_tolerance""gap_tolerance" > 1.0 to enforce the marks grouping (see also find_caltabfind_caltabFindCaltabfind_caltabFindCaltabFindCaltab).

Suggested values: 0.75, 0.9, 1.0 (default), 1.1, 1.2, 1.5

'alpha'"alpha""alpha""alpha""alpha""alpha":

Smoothing factor for the extraction of the mark contours. The use of 'alpha'"alpha""alpha""alpha""alpha""alpha" < 0.9 might be required for images that are out of focus, whereas 'alpha'"alpha""alpha""alpha""alpha""alpha" > 0.9 might be required for images which are sharp, but expose higher levels of noise. (see find_marks_and_posefind_marks_and_poseFindMarksAndPosefind_marks_and_poseFindMarksAndPoseFindMarksAndPose for more details)

Suggested values: 0.5, 0.7, 0.9 (default), 1.0, 1.2, 1.5

'max_diam_marks'"max_diam_marks""max_diam_marks""max_diam_marks""max_diam_marks""max_diam_marks":

Maximum expected diameter of the marks (needed internally by find_marks_and_posefind_marks_and_poseFindMarksAndPosefind_marks_and_poseFindMarksAndPoseFindMarksAndPose). By default, this value is estimated by the preceeding internal call to find_caltabfind_caltabFindCaltabfind_caltabFindCaltabFindCaltab. However, if the estimation is erroneous for no obvious reason or the internal call to find_caltabfind_caltabFindCaltabfind_caltabFindCaltabFindCaltab fails or is simply skipped (see 'skip_find_caltab'"skip_find_caltab""skip_find_caltab""skip_find_caltab""skip_find_caltab""skip_find_caltab" below), you might have to adjust this value.

Suggested values: 50.0, 100.0, 150.0, 200.0, 300.0

'skip_find_caltab'"skip_find_caltab""skip_find_caltab""skip_find_caltab""skip_find_caltab""skip_find_caltab":

Skip the internal call to find_caltabfind_caltabFindCaltabfind_caltabFindCaltabFindCaltab. If activated, only the domain of ImageImageImageImageImageimage reduces the search area for the internal call of find_marks_and_posefind_marks_and_poseFindMarksAndPosefind_marks_and_poseFindMarksAndPoseFindMarksAndPose. Thus, a user defined calibration plate region can be incorporated by setting 'skip_find_caltab'"skip_find_caltab""skip_find_caltab""skip_find_caltab""skip_find_caltab""skip_find_caltab"='false'"false""false""false""false""false" and reducing the ImageImageImageImageImageimage domain to the user region.

List of values: 'false'"false""false""false""false""false" (default), 'true'"true""true""true""true""true"

It is recommended to use find_calib_objectfind_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject instead of set_calib_data_observ_pointsset_calib_data_observ_pointsSetCalibDataObservPointsset_calib_data_observ_pointsSetCalibDataObservPointsSetCalibDataObservPoints where possible, since the contour information, which it stores in the calibration data model, enables a more precise calibration procedure with calibrate_camerascalibrate_camerasCalibrateCamerascalibrate_camerasCalibrateCamerasCalibrateCameras.

After a successful call to find_calib_objectfind_calib_objectFindCalibObjectfind_calib_objectFindCalibObjectFindCalibObject, the extracted points can be queried by get_calib_data_observ_pointsget_calib_data_observ_pointsGetCalibDataObservPointsget_calib_data_observ_pointsGetCalibDataObservPointsGetCalibDataObservPoints and the extracted contours can be accessed by get_calib_data_observ_contoursget_calib_data_observ_contoursGetCalibDataObservContoursget_calib_data_observ_contoursGetCalibDataObservContoursGetCalibDataObservContours.

Attention

A camera calibration data model CalibDataID cannot be shared between two or more user's threads. Different camera calibration data models can be used independently and safely in different threads.

Parallelization

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

Parameters

Possible Predecessors

read_imageread_imageReadImageread_imageReadImageReadImage, find_marks_and_posefind_marks_and_poseFindMarksAndPosefind_marks_and_poseFindMarksAndPoseFindMarksAndPose, set_calib_data_cam_paramset_calib_data_cam_paramSetCalibDataCamParamset_calib_data_cam_paramSetCalibDataCamParamSetCalibDataCamParam, set_calib_data_calib_objectset_calib_data_calib_objectSetCalibDataCalibObjectset_calib_data_calib_objectSetCalibDataCalibObjectSetCalibDataCalibObject

Possible Successors

set_calib_dataset_calib_dataSetCalibDataset_calib_dataSetCalibDataSetCalibData, calibrate_camerascalibrate_camerasCalibrateCamerascalibrate_camerasCalibrateCamerasCalibrateCameras

Alternatives

find_caltabfind_caltabFindCaltabfind_caltabFindCaltabFindCaltab, find_marks_and_posefind_marks_and_poseFindMarksAndPosefind_marks_and_poseFindMarksAndPoseFindMarksAndPose, set_calib_data_observ_pointsset_calib_data_observ_pointsSetCalibDataObservPointsset_calib_data_observ_pointsSetCalibDataObservPointsSetCalibDataObservPoints

Module

Calibration