Calibration and Correction of distortion
Even if the distortion of Telecentric Lenses is usually very low, it can still lead to unwanted measurement errors: CVTOOLS allows for extremely accurate calibration of the system by minimizing residual distortion, thus making the most demanding applications possible.
Just to give a feeling of the software capabilities, let's consider a telecentric lens featuring a distortion as low as 0.1%; this would normally lead to a 0.1 mm dimensional error at the image borders when imaging a 100 mm wide object, while CVTClib can lower such error to 0.007 mm (0.007%).
The calibration procedure just requires the acquisition of a few pictures of a checkerboard pattern; CVTOOLS's calibration functions take into account lens distortion (radial and trapezoidal), optical system misalignment and background illumination inhomogeneity.
System calibration data are stored into a small binary file which can be used during the measurement process.
CVTOOLS provides three ways to correct measures, so as to comply with the different stages of a measurement procedure (image processing, edge detection and edge analysis):
- Single point coordinates correction, to be used in combination with existing image processing and edge detection functions; CVTOOLS can elaborate the edge so as to obtain its undistorted metric coordinates
- Subpixel edge detection together with undistorted metric coordinates computation, by means of CVTOOLS functions straight on camera frames
- Entire image correction; you can pass a camera frame to CVTOOLS and get it undistorted, so that you can use your own image processing and edge detection functions.