Image Calibration and MOI

[ladouceuraj]

I am trying to create a program that will calculate the moment of inertia of a particular image.  I want to be able to prompt the user to select an image, calibrate the image based on real world settings, and calculate the MOI of a particular region.  Right now I can import the image, but I cannot calibrate based on user prompted data points.  I would like to have the image displayed, the user selects two points on the image, and then enters the real world distance between the points.  Any help would be great!

Alex

[muks]

One way is you can predefine the number of pixels = actual real worls distance in say mm. This way you can automate the entire process.

In particle analysis you have got inertia SUMXX, SUMYY. You can also try them to determine the inertia of the image.

[Jim_S]

Hello Alex,

I have a few questions to ask you about your application. You stated that you are able to bring the picture into LabVIEW. How are you doing this? Are you using the IMAQ driver? If you are then there is an example how to calculate the thickness of a ring which my be a good start with trying to implement this. There is also a tutorial about this and how to use the IMAQ driver.

I hope this information helps you with it.

[ladouceuraj]

yes we are using the IMAQ fileread.  We sort of have a manual calibration created but we are having trouble with the image threshold and mask.  We used IMAQ select line and then used the distance formula to find the distance in pixels and then converted to pixels per unit. We want to threshold the image to highlight the region of interest and mask the unwanted pixels but it's not working correctly. 

We can create a threshold and mask using vision assistant but we want to create a labview file that will prompt the user each time to threshold and mask the image. 

[muks]

Can you post an image?

[ladouceuraj]

sorry i can't post the images.  Does anyone know the units for the Moment of Inertia alogorithm in particle analysis?  I am looking for some sort of length^4

[muks]

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We can create a threshold and mask using vision assistant but we want to create a labview file that will prompt the user each time to threshold and mask the image.

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You can use a message pop up and while loop to to manually threshold the image if you like.