Calibrating the Image to Real World Units

Note: This topic describes the calibration feature when connected to an In-Sight vision system. If connected to an In-Sight 2000-130/130C or In-Sight 2000 series 23X vision sensor, refer to the Field of View (Width) section of Image Settings.

The Calibrate Image to Real World Units group box allows you to calibrate the results of Location and Inspection Tools, displaying their results in real world measurement units (microns, millimeter, centimeters and/or inches), instead of pixel values.

For In-Sight vision systems, calibration refers to the process of "mapping" the image area by establishing a relationship between features in the image and known, real-world measurement units. In this process, a two-dimensional (2D) transformation mathematically maps points from an image's pixel coordinates to real-world coordinates. Once an image has been calibrated, the Location and Inspection Tools will report their results in the calibrated (real-world) units.

There are six different types of calibrations, with varying degrees of accuracy, that are used to calibrate an In-Sight vision system: X/Y Scale, Edge to Edge, X/Y Edge to Edge, Circle, Grid, Import or 9-Point.

To assign a calibration to the job, select a calibration option from the Calibration Type drop-down menu: 

Note:
  • The X/Y Scale, Edge to Edge, X/Y Edge to Edge, Circle, Import and 9-Point calibration options rely on one to 16 user-specified points, respectively, in the image to relate the real-world measurements of the objects being inspected. These calibration options only compensate for linear and non-linear distortions. For the highest degree of accuracy, use the Grid calibration option.
  • When the default setting of None is used as a Calibration Type, all tool results will be returned in pixel coordinates.
  • Enable the Classic Orientation checkbox to view your calibrated results aligned to the traditional Spreadsheet View coordinates (Y/X).
  • When applying a calibration, the physical and optical set-up (the lens, vision system and the physical relationship between the vision system and the scene being acquired) must be the same for both the calibration and run-time operation. If any of these items is altered, the system must be re-calibrated. Therefore, it is recommended that the same vision system and lens be used to both calibrate and process the run-time images. The vision system and lens must also retain their original set-up and calibration settings. For example, changing the acquisition format (by altering the resolution) or moving the vision system will invalidate the computed 2D transformation that maps pixel to real-world coordinates.