Nonlinear Calibration Example is missed from my list::

[mangood]

hi member

this exmaple Nonlinear Calibration Example

http://zone.ni.com/devzone/cda/epd/p/id/5719

is missed from my labview examples

can any boday put vi of it

thank

best regards

[Joel-P]

Hello mangood,

The example that you referenced should have installed with the Vision Development Module. However I believe that this was included in versions 2009-2011 and it is no longer included with 2012. If you are looking for example code regarding Calibration in LabVIEW 2012 with the Vision Development Module I would recommend the following VI as a replacement. Using the example finder we can navigate to

Toolkits and Modules >> Vision >> Functions >> Calibration Models Comparison.vi

This should be able to show the different calibration methods, as well as contrast several nonlinear methods that are used.

Cheers,

Joel

[mangood]

ok  i found it

can you plase tell me what is this curves and why this thing moving along the image?>??

[Joel-P]

Hello mangood,

The curve is showing the distribution of the measurements made by the VI of the object as it moves across the image. The object that is moving is just a generic object that is being measured for its height. If you go to the Calibration Grid tab you can see an image of the calibration image that is being used. This image shows some distortion and this image is used to calibrate the images of the object that are being acquired and used for the measurement.

The calibration schemes are being compared and you can see the average measured height as well as the standard deviation of the measurements. The thinner that the graph is, the better the calibration as it has less variation across the images.

Cheers,

Joel

[mangood]

OK its complex in some how to me

to be clear and simplicity

I want to make a calibration to me image for sor two thing:

1- convert measure value to real value

2- solve the perspective error

what are the require for solving these two point??

[Joel-P]

Hello mangood,

1) The calibration being used in this example is converting to a real value. If you look at the measurements table, you can see that the units are in (mm) with an uncalibrated measurement this would be a measurement with a number of pixels as the distance.

2) All of the models that are compared in this VI will solve the perspective error.

I would also recommend that you take a look at the Perspective Calibration Example.VI which is available here:

Toolkits and Modules >> Vision >> Functions >> Perspective Calibration Example.vi

This example is a little bit simpler and uses a single calibration. Pay specific attention to the IMAQ Learn Distortion Model.vi and the other calibration VIs that are used with it. This should show you how to calibrate using a known calibration grid image.

Cheers,

Joel