WIre Diameter Measurements

Hello all. Part of my project requires real time measurement of wire diameter. The range of wire thickness ranges from 1-3mm and the camera will be fairly close to the wire being measured. The length segment of the wire being measured would only range from 1-2cm but can be adjusted as needed.

The process would be something like this:
-have a screen cap at a regular, small interval
-process image and calculate the diameter one frame at a time
-send diameter reading to a separate microcontroller via a communication protocol

The wire diameter measurement is used as part of a control system run on another microcontroller so I need to send the diameter reading in real time (obviously with some delay). Basically using the openMV camera as a diameter sensor in a feedback loop.

I have not started this project quite yet as I’m still looking for a solution to perform the above task. But I was wondering if i can do this completely on the openMV without the use of OpenCV on an external machine. And, if so, a general approach on how to calculate wire diameter would be appreciated.

I have some python programming experience. I dont have much experience in image processing hence why these openMv modules looked attractive.

I use blob tool for same project on plastic pipes.
I use 3 regions for 3 blobs and take the mean blob width of them.
Yeah everything runs on the camera without problem.
You must test it first to see if you can catch the wire variations.
I would use backlight for such project. But you must ensure that the wire will be completely in the same working distance.
Some photos of the camera may help more.
You will get pixels and not real mm. If you want with some math you will get estimated mm.
This camera doesn’t have calibration tools for the image though.

Hi. Thank you for the reply. Yes the wire will be in the same working distance. Im looking to measure variations in the 0.01mm range. The openMV camera will be approx. 1cm from the wire.

Would you mind sharing what kind of image processing steps/functions i would need to use in order to do what you mentioned? Im assuming I would take a picture, grayscale and theshold but im not sure what to do from there.


I already told you the steps.
See the blobs tool.
But I am pretty sure that it’s impossible to find such defects with this camera.
You need way more pixels and a calibration tool for the image and still will be difficult.
But if you already have the camera give it a try.

Oh ok got it. Didn’t know exactly what the blobs tool was. I just checked the blobs tool right now. Yes maybe you’re right but i do have the camera on hand so ill try it out. Thank you for the help.

1 Like

Send an image of what you see when you are ready.