Namespace for collection of calibration linescan functions from the Foundation package. More...

Classes
class	EdgeDetectionResult
	Result of the function DetectEdgesOfStripeTarget. More...

class	LineScanCalibrationConfiguration
	A set of parameters, which is used to configure linescan calibration calculated with function CreateLineScanCalibration. More...

class	LineScanCalibrator
	Result of the linescan calibration executed by the CreateLineScanCalibration function. More...

Typedefs
using	LineScanCalibratorPtr = std::shared_ptr<LineScanCalibrator>
	Convenience shared pointer for LineScanCalibrator.

Enumerations
enum class	ScanDirection { X = CExports::CVFScanDirection::CVFSD_X , Y = CExports::CVFScanDirection::CVFSD_Y }
	Specifies the scanning direction. More...

enum class	PreDefinedPixelSizeMode { DoNotUse , Use }
	Specifies if the predefined pixel resolution is used for the metric calibration. More...

Functions
std::pair< Point2D< double >, Point2D< double > >	CalculateTwoPointsForCalibrationOfMovement (const ImagePlane &imagePlane, const Area2D &aoi, Foundation::Transform2D::CalibrationPatternContrast contrast, int minContrast, const ValueRange< double > &pointSizeRange, const ScanDirection &scanDirection)
	Extracts two points which can be used for the calibration of the movement of linescan cameras.

EdgeDetectionResult	DetectEdgesOfStripeTarget (const Image &imageStripes, const Rect< int > &aoi, int numStripes, const ScanDirection &scanDirection, double threshold)
	This function detects edges from a calibration pattern with alternating black and white stripes.

std::unique_ptr< LineScanCalibrator >	CreateLineScanCalibration (const Point2D< double > &calibrationPoint1, const Point2D< double > &calibrationPoint2, double referenceDistanceCalibrationPoints, const EdgeDetectionResult &edgeDetectionResult, double referenceWidthStripes, const LineScanCalibrationConfiguration &configuration)
	Calibrates linescan cameras.

Detailed Description

Namespace for collection of calibration linescan functions from the Foundation package.

Online Manual: Calibration of Linescan Cameras

Remarks: CMake users: Link to imported target CVB::CvbFoundationCalibrationLineScan.

Enumeration Type Documentation

◆ PreDefinedPixelSizeMode

enum class PreDefinedPixelSizeMode

strong

Specifies if the predefined pixel resolution is used for the metric calibration.

Enumerator
DoNotUse	Predefined pixel resolution will not be used.
Use	Predefined pixel resolution will be used.

◆ ScanDirection

enum class ScanDirection

strong

Specifies the scanning direction.

The scanning direction has to be set in the configuration object LineScanCalibrationConfiguration used by the linescan calibration CreateLineScanCalibration.

Enumerator
X	Scans along the X coordinate.
Y	Scans along the Y coordinate.

Function Documentation

◆ CalculateTwoPointsForCalibrationOfMovement()

std::pair< Point2D< double >, Point2D< double > > CalculateTwoPointsForCalibrationOfMovement	(	const ImagePlane &	imagePlane,
		const Area2D &	aoi,
		Foundation::Transform2D::CalibrationPatternContrast	contrast,
		int	minContrast,
		const ValueRange< double > &	pointSizeRange,
		const ScanDirection &	scanDirection )

inline

Extracts two points which can be used for the calibration of the movement of linescan cameras.

The output of this function serves as input for the linescan calibration process executed by the CreateLineScanCalibration function.

If the image contains more than two points, the points which are nearest to the top and bottom edge (or left and right edge if ScanDirection is Y) are chosen.

Parameters

[in]	imagePlane	An image plane containing the calibration points.
[in]	aoi	Area of interest where the calibration points can be found.
[in]	contrast	Selects whether the image shows white on black or black on white dots.
[in]	minContrast	Minimum gray value contrast between the object and the background of the calibration points. Value to be set depends on the quality of the image taken.
[in]	pointSizeRange	The minimum and maximum size of the markers in the image in [number of pixels].
[in]	scanDirection	Scan direction of the camera.

Returns: first: X and Y coordinate of top calibration point if the ScanDirection is X, otherwise left point.
second: X and Y coordinate of bottom calibration point if the ScanDirection is X, otherwise right point.

Exceptions

Any	exception derived from std::exception including CvbException.

◆ CreateLineScanCalibration()

std::unique_ptr< LineScanCalibrator > CreateLineScanCalibration	(	const Point2D< double > &	calibrationPoint1,
		const Point2D< double > &	calibrationPoint2,
		double	referenceDistanceCalibrationPoints,
		const EdgeDetectionResult &	edgeDetectionResult,
		double	referenceWidthStripes,
		const LineScanCalibrationConfiguration &	configuration )

inline

Calibrates linescan cameras.

This function estimates coefficients of a 3rd order polynomial which calibrates linescan cameras. The polynomial corrects lens distortion as well as the camera's direction of movement (described by a scaling factor).

For the estimation of the lens distortion correction a pattern with alternating black and white stripes where the width of the stripes referenceWidthStripes is precisely known has to be acquired. For the camera's direction of movement a target with two circular markers can be used. The distance between the calibration points referenceDistanceCalibrationPoints has to be known, too. Note, that referenceWidthStripes and referenceDistanceCalibrationPoints must be provided in the same units.

In a first step the edges of the stripe target have to be detected via function DetectEdgesOfStripeTarget.

Second the two markers have to be extracted from the image via function CalculateTwoPointsForCalibrationOfMovement. Note, that if the encoder step of your setup is precisely known (e.g. in [mm/scanline]), you do not need to acquire an image with markers. You may manually define fictive calibration points and the corresponding reference distance:

double encoderStep = ...                               // mm/scanline
auto calibrationPoint1 = Cvb::Point2D<double>(0, 0);   // first point
auto calibrationPoint2 = Cvb::Point2D<double>(1, 0);   // second point
referenceDistanceCalibrationPoints = encoderStep;      // reference distance between calibration points in[mm]

Parameters

[in]	calibrationPoint1	First calibration point (left or top).
[in]	calibrationPoint2	Second calibration point (right or bottom).
[in]	referenceDistanceCalibrationPoints	Reference distance between the two calibration points (same units as referenceWidthStripes).
[in]	edgeDetectionResult	Result returned by DetectEdgesOfStripeTarget.
[in]	referenceWidthStripes	Reference width of stripes in calibration pattern (same units as referenceDistanceCalibrationPoints).
[in]	configuration	Configuration of linescan calibration.

Returns: A linescan calibrator including a transformation and its quality.

◆ DetectEdgesOfStripeTarget()

EdgeDetectionResult DetectEdgesOfStripeTarget	(	const Image &	imageStripes,
		const Rect< int > &	aoi,
		int	numStripes,
		const ScanDirection &	scanDirection,
		double	threshold )

inline

This function detects edges from a calibration pattern with alternating black and white stripes.

The output of this function is used by function CreateLineScanCalibration calculating the linescan calibration. This function internally calls Edge::FindAllEdges, where all input parameter are described, too. For detailed information see the documentation of the CVB edge tool.

Note, that the given area of interest aoi must only cover areas with stripes.

Note: The given number of stripes numStripes is only used for memory allocation. It does not necessarily have to precisely match the number of stripes, but it must be equal to or greater than the actual number of stripes. If the selected value is too low, an error is thrown ("bad allocation").

Parameters

[in]	imageStripes	Calibration pattern with alternating black and white stripes.
[in]	aoi	Area of interest in the given image.
[in]	numStripes	Number of stripes in the calibration pattern.
[in]	scanDirection	Scan direction of the camera.
[in]	threshold	Threshold for gray value change.

Returns: Result of the edge detection.

Classes

Typedefs

Enumerations

Functions

Detailed Description

Enumeration Type Documentation

◆ PreDefinedPixelSizeMode

◆ ScanDirection

Function Documentation

◆ CalculateTwoPointsForCalibrationOfMovement()

◆ CreateLineScanCalibration()

◆ DetectEdgesOfStripeTarget()