pitch measurement (threads of a screw)

[BodkinArrow]

Hi ,

I would like to measure the pitch of a screw, need idea for an algorithm. Please help. This would be using backlight.

[Hatef.fouladi]

there is several vi approve for this reason in vision toolkit in machine vision part
but for fundamental help
you have to make binary image first by using threshold on intensity
then try to find screw direction and position but geometry matching and after that using find edge in vertical diraction of screw to get what you need

[BodkinArrow]

Hi. On perform thresholding and getting a binary image; I stand to lose information that is much needed for measurement.

[Hatef.fouladi]

there is several thresholding method you have to check all of them to find best method
elso if you lost information in all off method it show that you have not choice appropriate lighting method and you have to change it