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CreateRectificationMap_WorldUnits


Header: FIL.h
Namespace: fil
Module: Calibration

Computes a spatial map for transforming distorted images to rectified images defined in world coordinate plane. Defines the output geometry in world units.

Applications: Specification of output geometry in world units is especially useful in image stitching.

Syntax

C++
C#
 
void fil::CreateRectificationMap_WorldUnits
(
	const fil::ImageFormat& inImageFormat,
	float inLeftBound,
	float inRightBound,
	float inTopBound,
	float inBottomBound,
	const ftl::Optional<float>& inWorldScale,
	bool inInvertedWorldY,
	fil::InterpolationMethod::Type inInterpolationMethod,
	const fil::RectificationTransform& inTransform,
	fil::RectificationMap& outRectificationMap
)

Parameters

Name Type Range Default Description
Input value inImageFormat const ImageFormat& Input image format.
Input value inLeftBound float World X coordinate of left side of generated output image.
Input value inRightBound float World X coordinate of right side of generated output image.
Input value inTopBound float World Y coordinate of top side of generated output image.
Input value inBottomBound float World Y coordinate of bottom side of generated output image.
Input value inWorldScale const Optional<float>& 0.001 - NIL [pix / world unit] Specifies the scale for output image. By default scale is calculated such that there will be no rescaling at the center of output image.
Input value inInvertedWorldY bool False Set to true if world coordinate system has right-handed orientation, also known as mathematical or standard. This effectively mirrors the rectified image vertically.
Input value inInterpolationMethod InterpolationMethod::Type Bilinear
Input value inTransform const RectificationTransform& Transform's camera model is needed for undistortion of image, when not supplied the generated map will assume undistorted image on input. Transform's homography is needed for transforming to given world plane, when not supplied the generated map will only remove distortion of image.
Output value outRectificationMap RectificationMap&

Description

Creates a RectificationMap, which is used by RectifyImage filter for image rectification onto a defined world plane. Point locations on rectified images are related to the world plane (defined by inTransform) only by translation and scaling.

The inTransform may not contain a camera model – in such case the the generated map will assume undistorted image on input.

The output image dimensions, resolution and cropping are specified by:

  1. inLeftBound,inRightBound,inTopBound,inBottomBound - real world coordinate boundaries of the area which output image will cover.
  2. inWorldScale - the scale for output image, defined in pixels per world unit.

For example, if one is interested in area spanning from (0,0) to (10,6) world coordinate, with resolution 100 pixels / world unit, then inputs would be set as follows:

  • inLeftBound = 0
  • inRightBound = 10
  • inTopBound = 0
  • inBottomBound = 6
  • inWorldScale = 100

Auxiliary data contained inside the RectificationMap describes the relation of rectified image to the world plane.

Examples

Left: original image, as captured by a camera, with mild lens distortion present. Right: rectified image with annotated length measurement.

Errors

List of possible exceptions:

Error type Description
DomainError inLeftBound should be less than inRightBound
DomainError inTopBound should be less than inBottomBound