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Camera Calibration and World Coordinates Calibration from Chessboard Grid

Aim

In this example a real-world positions of caliper tips are calculated and a distance between them. The caliper is lying on a flat surface, however the camera is not perpendicular to the surface, and also camera lens has non-negligible distortion.

Input

A set of images with camera calibration grid. An image of a calibration grid lying on the world plane. An image of the caliper.

Output

Real-world positions of caliper tips. Distance between caliper tips.

Hints

This example shows a typical problem of measurement in a real-world coordinate system.

Despite the camera lens and perspective distortions the vision analysis can be done on an input image.
After image point coordinates of caliper tips are found, they are transformed to real-world coordinates.
The necessary calibration data is calculated with help of a calibration gui.

Solution (Studio)

Macrofilter Main

Used Filters

Icon	Name	Description
	GetArrayElements	Extracts up to 8 individual elements from an array.
	AssertRealInRange	Asserts that a real value fits the specified range.
	PointToPointDistance	Measures the distance between two points.
	ImagePointsToWorldPlane	Undistortion, image to world coordinate transformation.
	CreateArray	Creates an array from up to 8 individual objects.
	LoadImage	Loads a single image from a file.