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CreateUndistortionMap

Computes a spatial transform map for undistorting images from a calibrated camera.

Syntax

void avl::CreateUndistortionMap
(
	const avl::Matrix& inCameraMatrix,
	const avl::LensDistortion& inDistortion,
	atl::Optional<int> inMapWidth,
	atl::Optional<int> inMapHeight,
	const avl::Vector2D& inMapShift,
	float inMapRotation,
	float inCameraRotationY,
	float inCameraRotationX,
	float inCameraRotationZ,
	const avl::ImageFormat& inImageFormat,
	avl::InterpolationMethod::Type inInterpolationMethod,
	avl::SpatialMap& outSpatialMap,
	atl::Optional<avl::Region&> outOutputRegion = atl::NIL
)

void CreateUndistortionMap
(
	Matrix inCameraMatrix,
	LensDistortion inDistortion,
	int? inMapWidth,
	int? inMapHeight,
	Vector2D inMapShift,
	float inMapRotation,
	float inCameraRotationY,
	float inCameraRotationX,
	float inCameraRotationZ,
	ImageFormat inImageFormat,
	InterpolationMethod inInterpolationMethod,
	out SpatialMap outSpatialMap,
	out Region? outOutputRegion
)

Parameters

Name	Type	Range	Default	Description
inCameraMatrix	const Matrix&
inDistortion	const LensDistortion&
inMapWidth	Optional<int>	1 -	NIL	Width of output map, default: same as example image.
inMapHeight	Optional<int>	1 -	NIL	Height of output map, default: same as example image.
inMapShift	const Vector2D&			Translation from the principal point on the image plane.
inMapRotation	float			Rotation of the principal point on the image plane.
inCameraRotationY	float			Rotation of view around Y axis (a.k.a. Pan, Azimuth or Yaw)
inCameraRotationX	float			Rotation of view around X axis (a.k.a. Tilt, Elevation or Pitch)
inCameraRotationZ	float			Rotation of view around Z axis (a.k.a. Roll, Horizon)
inImageFormat	const ImageFormat&			Information about dimensions, depth and pixel type of the image
inInterpolationMethod	InterpolationMethod::Type		Bilinear
outSpatialMap	SpatialMap&
outOutputRegion	Optional<Region&>		NIL

Description

After determining the intrinsic camera matrix, and intrinsic distortion coefficients using CalibrateCamera, this filter can be used to undo distortion of the images (undistortion).

The undistortion is performed through a general spatial transformation, using RemapImage. The result is a SpatialMap, i.e. a description of this transformation.

Examples

A calibration pattern: original - before undistortion.

A calibration pattern: remapped using RemapImage.
The SpatialMap used was generated with CreateUndistortionMap, for inInterpolationMethod = NearestNeighbour and Bilinear.

Remarks

The interpolation method chosen affects the speed of image remapping. Nearest neighbour is the fastest method, but bilinear interpolation provides higher quality.

The inImageFormat input describes dimensions and pixel format of the images that will be remapped with a RemapImage filter. Also an example image may be connected to this input and the format information will be extracted from it.

The outOutputRegion describes the region of valid pixels. If it does not cover the output area, it should be passed to RemapImage, to suppress the invalid pixels. To increase coverage, provide different values for inMapHeight and inMapWidth - to limit the output area to a valid region.

Errors

Error type	Description
DomainError	Empty camera matrix on input in CreateUndistortionMap.
DomainError	Camera matrix must be 3x3 in CreateUndistortionMap.
DomainError	Format of an empty image on input in CreateUndistortionMap.