Help me understand how/when to apply an evaluation filter (Gauss) to a 2D Curve

2026-06-04T12:53:24Z

Hello,

I am hoping to get some input on how best to use, or when to use a gaussian low pass filter on a 2D Curve. For some context, my organization does a lot of profile controls - for example all unspecified surfaces are typically controlled by a profile of .020 to DATUM A/B/C. The vast majority of our profile measurements are captured through 2D or 3D curves that are a combination of linear surfaces and radii. (Screenshot of feature below is an example of what our strategy may look like.) Up to this point we have not applied filter/outlier elimination to the features themselves, and typically just insert the raw data into a Line or Surface profile characteristic.

After reading up a bit on the Gauss low-pass filter setting that can be turned on/off on our curves I believe it may be appropriate for us to start utilizing that setting at times. So here is my understanding of the usage.

-The filter is used to smooth a profile to compensate for surface finish/roughness of material

-A minimum of 7 points is required (question here from me is this per wavelength based on the Lc setting, or for the entire curve length?)

-The wavelength cutoff setting (Lc) should be selected based on the expected roughness of the surface? (is the surface roughness conversion chart I have in a image below a good resource for selecting 'Cut-off length / Lc?'

-What is the 'connect segments' setting is under the filter

-In the third image below, is it appropriate to use this filter, on this specific curve when measuring it as a profile, and what should the specific settings be? The maximum allowed surface roughness is 125 (microinches) but will likely fall between 30-62 (microinches.)

-Any suggestions on how or when to appropriately apply the Gauss, low-pass filter to a 2D curve feature that is measuring surface profile would be greatly appreciated..