I have traced profile of a feature using contact probe surface roughness measurement device. The problem is that the software can allow sampling length of a minimum of 800 microns (0.8 mm) to measure surface roughness. I want the sampling length to be around 20-30 microns. Is it possible through other software or through image processing software like ImageJ. The data (or curve) is captured in X-Z format and not in 3D.
Dear Tribeni, Given sampling distance Dt, sampling frequency is given by fs=1/Dt. Frequency characteristic function after M point moving average is described by G(f)=1/(2pi f tau) Sqrt[2(1-cos2 pi f tau)] where tau =M Dt. Solving G=1/Sqrt[2] for f, we obtain cutoff frequency as fc=0.443/ tau. Thus, cutoff length is tau_c=1/fc= tau /0.443.
If you want to cutoff length 20 microns, tau=0.443x20 (microns)=8.86(microns). Usual surface profile meter has sampling distance of Dt=0.5 microns. If this is case for your system, moving average point should be M= tau /Dt>18.
So, your task is confirm sampling distance is 0.5 microns, first. Modify moving average point to 8 in your software. Surfcoder has output of surface profile data in Excel. Using out put, you can write code M point moving average on MATLAB. I recommend you MATLAB. Shigeo
Hi,
as your data are a time series, not an image, ImageJ or other image processing tools are not the best approach for this. However, you can use time series and signal analysis software like Dataplore (http://dataplore.com) which is not limited with respect to the sampling length.
Good luck and best regards
Ralf
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