Accuracy problem in measuring position

[AKanna]

Hi,

 I am measuring a position and orientation of the object. When the object directly under the camera lens its giving correct position and orientation but when the object away front the camera lens(but the object is inside the image) its showing not accurate position. Is this problem because of camera lens or height of the camera is to high or am I missing any stages or ...

Software using=Ni vision builder 2011

Stages I did = Image acquiring, image processing, Region of interest, calibrating, Geometric pattern matching

Hope you have understood my question

[AKanna]

I think its due to the distortion. But how to solve the distortion problem in VBAI?

[ChristopheC]

Vision Builder AI features a calibration step that you can use to correct innacuracies introduced by lens distortion.

You'll get the best results by calibrating your system using a grid of dots.

To create a calibration, select Tools>>System Resource Manager.

You can apply it within the acquisition steps (Calibration tab), or by inserting a Calibration step.

I invite you to look at the Calibrate Image Step Example located in the examples folder.

Hope this helps.

Christophe

[mkais]

Dear Sir,

You can calibrate from a file that already in your Vision Builder folder to find.

here is some interesting Information about Calibrating with Vision to have more accuracy:

Solving a Machine Vision Application with NI Vision Builder for Automated Inspection

 http://www.ni.com/white-paper/4127/en