Simple Calibration

When the axis of your camera is perpendicular to the image plane and lens distortion is negligible, use a simple calibration. In a simple calibration, a pixel coordinate is transformed to a real-world coordinate through scaling in the horizontal and vertical directions.

Use simple calibration to map pixel coordinates to real-world coordinates directly without a calibration grid. The software rotates and scales a pixel coordinate according to predefined coordinate reference and scaling factors. You can assign the calibration to an arbitrary image using the IMAQ Set Simple Calibration VI.

To perform a simple calibration, set a coordinate reference—composed of an angle, center, and axis direction—and scaling factors on the defined axis, as shown in the following figure. Express the angle between the x-axis and the horizontal axis of the image in degrees. Express the center as the position, in pixels, where you want the coordinate reference origin. Set the axis direction to direct or indirect. Simple calibration also offers a correction table option and a scaling mode option.

Simple calibration is performed using the IMAQ Set Simple Calibration VI. Use the Calibration Axis Info control to define the coordinate system. Use the X Step and Y Step elements of the Grid Descriptor control to specify the scaling factors. Use the Corrected Image Scaling control to set the scaling method. Set the Learn Correction Table? control to True to learn the correction table.

1   Origin