NI Vision for LabVIEW

IMAQ Learn Distortion Model VI

  • Updated2023-02-21
  • 6 minute(s) read
Owning Palette: Calibration
Requires: NI Vision Development Module

Learns a distortion model of the camera and lens setup. If your camera is not perpendicular to the object under inspection, you can combine distortion modeling with perspective calibration.

Examples

Supported Image Types

8-bit unsigned grayscale 16-bit unsigned grayscale 32-bit RGB 16-bit signed grayscale floating point grayscale 32-bit HSL

IMAQ Learn Distortion Model

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Distortion Model Setup specifies the distortion model settings to use.

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Distortion Model specifies the type of distortion model.

None (-1)

Do not learn a distortion model.

Polynomial (0)

Learn a polynomial distortion model. Using multiple coefficients increases computation accuracy at the expense of speed.

Division (1)

Learn a division distortion model. Use this distortion model when the image contains minimal distortion.

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Polynomial Model Setup configures the polynomial model.

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Radial Coefficient specifies the number of polynomial coefficients to use. For more information, see Spatial Calibration Concepts.

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Tangential Coefficients enables correction for tangential distortion. Correct for tangential distortion when sensor misalignment occurs. For more information, see Spatial Calibration Concepts.

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Calibration Template Image is a reference to the image containing calibration information.

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Image is a reference to the source image.

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Reference Points is the set of reference points to use in learning a calibration. Create the reference points manually or use the IMAQ Calibration Target to Points - Circular Dots 2 VI.

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Pixel Coordinates are the coordinates of 3 reference points in the image, in pixels.

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X is the x-coordinate of the point.

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Y is the y-coordinate of the point.

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Real World Coordinates are the relative locations of the dots in the real world.

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X is the x-coordinate of the point.

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Y is the y-coordinate of the point.

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Unit is the unit of the Real World Coordinates.

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Image Size specifies the size of the calibration template image.

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X is the horizontal size of the image.

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Y is the vertical size of the image.

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error in (no error) describes the error status before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.

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status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.

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code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.

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source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

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Add Points and Learn (True), when TRUE, adds points and learns the distortion model. When FALSE, only points are added. The default is TRUE. If you learn calibration using one image, set this parameter to TRUE to add points and learn the calibration template. If you learn calibration from multiple grid images, set this parameter to FALSE for the first n-1 images, then set it to TRUE for the last image.

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Calibration Template Image Out is the reference to the output image.

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error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.

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status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.

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code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.

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source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

Examples

Refer to the following for examples that use this VI.

  • LabVIEW\examples\Vision\Calibration\Perspective Calibration.vi

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