Using NI Vision Assistant

[kent 2008]

Does anybody know how to automate measurements of images using NI Vision 8.0?? PLEASE HELP!!

-Desperate Grad Student

[iRish]

Hello kent2008,

You mention that you want to automate measurements in Vision Assistant.  What are your trying to measure?  Distance/angles between objects?  Can you provide us with a sample of the image you want to look at? Do you want to run this in a loop?  Which operating system are you running?

Basically you just need to create a script that will load image, find the features you wish to measure then run the measure tool between the two points of interest.

If you can outline your application more, then myself, and the forum community should be able to help you.

Regards

[kent 2008]

Hello iRish,

Well, I am running a program through LabVIEW 8.0 which takes snapshots of images. I then take the images and load them into Vision Assistant for image analysis. I inevitably want to find the diameter of each image. One problem is that there are multiple images, in a single snapshot, that need to be measured. It would be great if the diameter measurements could be automated. However, I am a novice when it comes to LabVIEW and Vision.

Attached you should find an example of an image I am working with. Do you also have any advice for learning applications of LabVIEW and Vision without going through the pages and pages of instruction?

Thank you very kindly!

Malcom B

[iRish]

Hi Malcolm,

This is definitely possible using Vision Assistant.  There are 3 tools you will want to try and they are located under the Machine Vision tab in Vision Assistant.
1.  Pattern Matching
2.  Geometric Matching
3.  Shape Detection.

Essentially you provide it a template image of one of the objects you want to find.  Any image passed in will be examined to see whether or not the shape exists.  It also can handle differences in scales, rotations and brightness!

Depending on which function you choose, it should return to you the coordinates of each found template in the image, which you can automatically measure between.

Regards

[kent 2008]

Hello Rishi,

Thanks for your response. I have utilized the Machine Vision Tab in Vision Assistant, but it won't allow me to perform image analysis because my image is a 32 bit image. Do you know how I can modify my 32 bit image to a binary image? I am also encountering difficulties with the template loading. I know what shape I want to load, but when I tried to load it, all of the similar shapes in the image were not measured.

I am searching for a batch measurement process that will measure every particle in the image with similar shape.

Thanks again for taking time out to help me out!

-Malcom

[another_novice]

There's a batch run function in Vision Assistant (look under Tools in the menu) that lets you run a script on multiple images and save the results. I think that's what you're looking for.

[kent 2008]

Thank you for the reply!

I have been toggling around with the batch process fxn to no avail. The batch process requires a script to be effective. I am having difficulty creating a script that addresses my specific needs. I want to be able to find the average diameter of ALL of the circles in my image. Currently, I am using the line profile and manually measuring each circle. With the number of images I have, it will take a LONG time. If you or anybody else can help with that, I will be very grateful!!

-Malcom

P.S. An example of an image I work with is attached

[another_novice]

Malcolm,

I think the particle filter and particle analysis tools in Vision Assistant 8.0 will give you the data you need. It sounds like max feret diameter is the characteristic you want to track.

Your biggest challenge is in binarizing the image so as to turn the bubbles (if that's what they are) into particles.

You might try using this script as a starting point:

[kent 2008]

Thank you for the reply!

What format is the  "bubble script" in? I am having difficulty reading it ( I have an older version of Windows; I am getting text like: @##$%$%). I was able to get to the point where the majority of my bubbles are outlined, so I know I am nearing completion of the script. Thanks again for your help!

-Malcom

[another_novice]

Format? I just did a file save from Vision Assistant 8.0. I notice that the extension is .scr, which Windows thinks is a screensaver, but you should be able to open it from Vis Asst.

In terms of image processing, you might try capturing an image with no bubbles and then doing a subtraction (or other logical function) to accentuate the objects you want to see.

EnJay