Selecting surfaces on similar or identical centroids

Hi all,

i would like to select all surfaces on a specific plane.

Here is my issue:

a polysurface has been turned into separate surfaces.

once this has been done i essentially have ‘duplicates’, sat one behind each other (see image)!

I have looked at doing this by centroid of panel and X axis position, but they (inevitably) are all a little off. is there a way of either:

reducing the sensitivity of the centroid search to say 1 decimal place, or:

selecting them another way?

can i then ‘split’ similar or identical x axis centroid’s into two separate lists?

Many thanks!



I’m not quite sure what you are trying to do. If you like to select a surface based on a plane you can use
a simple approach like this: (17.6 KB)

sorry, let me explain.

i have a set of surfaces which were previously surfaces and have been exploded. this is required to undertake an analysis if single surfaces (poly’s dont work).

If you zoom in, you will see that the single looking surface is actually 2 separate, but very close together surfaces.

i would like to remove the inner most of these two surfaces on each occaion, leaving me with a single set of surfacaes.

initially my idea was to find the centre of each surface and remove one of each that were closest. does this work? is there a simple way of doing this? or is there a method of picking on the the ‘back’ surface in each instance?

many thanks in advance!


Post surfaces please.

Depending on the normals i would probably use Point Plane Side pufferfish component – after grouping, most likely by proximity.

Hi Rickson,

im not sure what you mean, i have posted surfaces, do you mean the actual Rhino?


Yes, actual rhino surfaces.

3. Attach minimal versions of all the relevant files
If you have a gh file you have a question about, attach it to the post. Do not expect that people will recreate a file based on a screen-shot because that’s a lot of pointless work. It’s also a good idea to remove everything non-essential from a gh file. You can use the Internalise Data menu option to cut everything to the left of a parameter

RH Question.3dm (2.5 MB)

got it. thanks for the heads up on the effective questions!


The point groups for some reason (xy sort?) indexed them nicely. I culled the single units. So no other filters required… at the moment.

re (7.5 KB)

this is great, thank you!

very useful