Sample of 2D array of points - Fit 2D FFT to find missing points

[chris_1243]

I have an image of dots that are close to being evenly spaced but are not quite. I would like to fit something like a 2D sinusoidal plane wave to the points such that each point in the image is essentially a peak. My goal is to detect the missing peaks where there are no dots. First, I would like to assume the frequency is constant but the reality is that it is slightly different from the left-side of the image to the right-side. In fact, the peaks (points) tend to be a little closer together the closer to the left- and right- sides of the image. The top- and bot- of the image should be very consistent in the frequency of dots. I know there are ways to do this with LabVIEW tools. Should I use some of the FFT VIs to extract the frequencies between dots; or would it be better to perhaps fit a 2D plane wave model to the existing points? Any thoughts on direction here would be appreciated. 

Alternatively, I've thought about grouping the dots in their respective "waves" and then calculating the average spacing between them both left-to-right and top-to-bot, and then trying to determine the missing dots with that information. But if there was a fitting method or an FFT function I could use to simplify this that would be helpful

[Andrea.W]

Hey Chris,

You are on a good track of options to detect these peaks, and the method you choose would be affected by how accurate you want your measurements of those peaks to be, i.e. a model would yield a more general location whereas using VIs to find frequencies would probably give a more precise answer. 

I have attached a couple links regarding the FFT express VI and a discussion post about detecting missing peaks to reference. There are other data fitting VIs in LabVIEW that could get you started as well.

Thank you, 

Andrea

https://forums.ni.com/t5/LabVIEW/Missing-peaks-in-waveform-peak-detection-vi/td-p/931562

http://zone.ni.com/reference/en-XX/help/372614J-01/lvfpga/fpga_fft/