How to calculate the height of an object in a picture

[zqx]

How to calculate the height of an object in a picture (pixel)

[altenbach]

What defines an "object"? Can you show an example picture?

[zqx]

like this,i want to calculate the height of the green one object.how can i do?

thanks

[udka]

If you want to calculate the object dimensions in terms of pixels, use Particle Analysis: Particle Analysis will give multiple parameters just check them:
https://zone.ni.com/reference/en-XX/help/370281AC-01/nivisionconcepts/particle_measurements/
-If you want the real world dimensions then you have to use Calibration and apply on to the original image/pixel dimensions.

[moderator1983]

No doubt, you already knew that number of pixels will tell the height (obviously in pixels) of the object. But at the same time you also want to capture a ruler placed at same depth (of field) as the object is so that you can determine how much each pixel, in the image, corresponds to a given engineering unit of length.

You might also be interested to check machine vision library.