How to Rotate Calipers?

[rhowes]

Hello Everyone. Thank you for looking.

I am new to NI products. I Vision builder finding my "line of silicone sealant" and making measurments and confirming the width. Now I need to do that if the sealant line is rotated. I added coordinates. I added a match pattern. Then I slid my line of seal over to the rounded end and added a find circular Edge. That all works great! The problem is... My Caliper Widths are verticle even if the line of selalant is at an angle. How do I rorate the calipers to get the width of the Sealant Object at the angle of the line? OR How do I rotate the image to horizontal so that the calipers make the corect measurement?

I saw something about IMAQ processes but I have no idea how to do that. Can anyone please help. I'll attach the image and you will see where my width problem occurs.

[ChristopheC]

Hi,

You can use the Create Region of Interest Step to create a Rotated Rectangle, whose angle is defined by the the angle of the sealant line that you previously computed.

The Create Region of Interest step allows you to create region of interests based on previous measurements. You can then use this ROI to measure the width of the sealant with the Caliper.

Also, it looks like you're thresholding the portion of the image where you want to measure the width. I would recommend against that, as the caliper tool is based on Edge Detection, or contour extraction, which will be much more accurate when computed on the grayscale image. Thresholding is used to get a binary image to analyse particles. For metrology applications, most machine vision tools will give you better results with the grayscale image.

I am attaching a simple Vision Builder inspection that shows the use of the Create Region of Interest.

Hope this helps,

Christophe

[rhowes]

Thank you for thr response and I'll have to learn more about the tools.

I should of mentioned that the angle will be random. I vaguely remebred looking at a rotate ROI last month but that is a fixed position which I believe will not work.

Does grey scale calculate pixels in the area? I believe that would be less accurate than just counting the "pixels" across the object. 

[Brad]

Another option that it looks like you may already be using is to setup a coordinate system. Make sure to choose the option for the coordinate system to move in the X, Y direction as well as rotate. Once you have a coordinate system, all the processing/analysis steps in Vision Builder can use that coordinate system and will have the ROI you draw when creating the step shift and rotate based on the coordinate system. You can see the shipping example in the Vision Builder AI folder called Detect Objects Example.vbai (there are several that illustrate how to use coordinate systems, but this one is very simple and show multiple steps repositioning their ROI based on a coordinate system).

Hope this helps,

Brad