Octagon measurement

[sppelletier]

Hi there,

I'm trying to make measurements on an octagon.  I need to know the Max width, min width and center of mass.  I also need to evaluate the chipping on the side of the octagon (dark area on the side of the octagon). The chipping measurement must be made perpendicular from the side.  I would have use the blob tool if it would not have been the case.

I'm using 

I thought of using the clamping tool but the measurement must be automated so I need to figure a way to build an algorithm.

Any idea?

Thank in advance

[BruceAmmons]

My thoughts:

You can create a mask for the (ideal) entire octagon by converting it to binary, then use convex surface to fill in all the chips.

The ideal octagon can be converted to a depth gage by using IMAQ Distance or Danielson.

By manipulating the original image to get a binary image of the chips, you can combine it with depth gage to get distance from edge.

Bruce

[sppelletier]

The problem is that the sides of the octagon are never the same length. the sidse can be longer/shorter than the mask.

as for the chipping, I tought of finding a straight edge of one side to start. then place the cordinate system on this edge and sweep ( one line ROI incremented by 1 pixel at a time from end to end of the side)  and check for the chipping.

what do you think?

[Greg-H]

Hi,

I think that your idea of sweeping the edge will work to check for chipping.  As far as actually detecting the octagon, you could threshold the image then use a detect object step to locate where in the picture the octagon is.  Then you could specifiy a coordinate system and then a mask or ROI based on this.  You could set the size of the ROI/Mask proportional to the size of the detected object and this should account for the change in size.

Regards,

Greg H.