How can I mask points of a freeform surface?

[[No...]]

Hi, I measure a very small freeform surface and need to exclude a certain circular area from evaluation. I use scanned point sets in my strategy and it would be very difficult to exclude the area during scanning, because the surface is so small and the tip radius is rather large in comparison. I fear the stylus might touch that area anyway and produce faulty points. It'd be better to mask the area afterwards, but I have no idea how to do that.

[[Ma...]]

I think you can not.

But if you make a 3d curve from FF path, then you can recall measured points into a curve and now you can mask and evaluate.
But to be sure we would need to know how FF looks like and it's points/path.
With points far away and big curvature you can have wrong evaluation.

Also i just wonder - you could possibly recall filtered points from curve back into a FF

[[No...]]

The surface looks like this. The area I need to exclude is marked in green on the top. The stylus in the image is 1.5 mm.

The strategy consists of 5 point sets. I can not use a smaller tip radius, otherwise I couldn't reach the points in the top left corner. Probe change is not an option for now (only the last resort if everything else fails)

Edited 5 hours ago

[[Ma...]]

Since i have done similar things and FF does not allow masking points i would go with that curve option.

For correct creation of a curve you have to have no measured points on recalled feature.
So either remove measured data from feature or just copy it and do recalled curve from that copy.

Now check vectors or invert them and recall measured data into it. Do masking in evaluation tab and use that copied ff to recall filtered measured points from curve.

Perhaps this easy way should be sufficient.

If i need to have correct curve, then i do next steps:

• after recalculating first curve - it will create it's spline
• go to element creation window and switch to 2nd window
• from selection select "From curve" and select that spline - it will allow you to control distance of points along curve's spline and also exactly on CAD model.
  This is needed when you have bigger distance of points in curve and spline is not following curvature of a model ( air scanning )

If you need i can make some screenshots

[[No...]]

Thanks Martin, but I ended up recalling the points to a copy of the FF and masking the area by placing four selection boxes around it. Very clumsy method, but it worked.