Measure area of a doughnut

[PaulG.]

I need to give a customer an easy method of measuring the pixel area of a doughnut shape. We already measure rectangle/squares and oval/circles. How do I get 2 ROI's on/from the same image to subtract the two?

[ryanm]

If the doughnut shape is a circle, the easiest way to compute the area is by using the annulus ROI. I have attached a simple LabVIEW Program showing this. If the doughnut shape is elliptical, then use the ellipse tool and select the first ellipse. To select the second ellipse, the user must hold down the control key. Both ROIs will be output the ROI property node. I have added comments on the block diagram to help explain this as well.

Ryan M.
National Instruments

[PaulG.]

I believe that will do the trick. Thanks!

[zäpfle]

Do you know, How can I compute the area (pixel) of a ellipse?

[BruceAmmons]

If the lengths of the long and short axes of the ellipse are L1 and L2, the formula for area is L1 * L2 / 4 * Pi.

Bruce

[zäpfle]

thanks for the answer Bruce, I knew the formula, but I thought there is a solution with NI Sub VI's

greetings

[Hami45]

hello guys .

i want to calculate the area of shape that i attached or a shape like that .

please help me