tamte
Did you try what I suggested? The Clip S

Thanks that converted my mind.
Yes, I understand your example, but I can't reproduce it: - for example - when I specify in node blast a group of potholes to be removed, houdini removes all polygons


I have little practice

tamte
for example:
- Sphere SOP
- Clip SOP: Clipped Edges On (this will output "original" clipped edges in a group)
- Blast SOP: delete a few polygons on borders to create those cavities
the "clippededges" group will contain just the original clipped edges

Why do you keep using Clip "SOP"?
Yes, I know it's surface operation (s) but what is the purpose of using these 3 letters?

tamte
or example:
- Sphere SOP
- Clip SOP: Clipped Edges On (this will output "original" clipped edges in a group)
- Blast SOP: delete a few polygons on borders to create those cavities
the "clippededges" group will contain just the original clipped edges
Tomas Slancik

Just begin to learn...

here is an example file

Artadecram
Why do you keep using Clip "SOP"?
Yes, I know it's surface operation (s) but what is the purpose of using these 3 letters?

it's pretty common to mention the context when mentioning nodes as many contexts have nodes of the same name
and while clip and blast are not one of those, mentioning SOP makes it clear and futureproof