With the new "Details" we are given "Naked edges". I looked at one of my models and saw the naked edges, but what am I looking at? I looked to see if there was some problem at these edges and I could find none. Of what use is this information?

Hi Tim, a "Naked edge" is an edge that belongs to only one surface instead of where 2 surfaces are joined together.

The main use for identifying these is if you're trying to make your object into a closed solid. A closed solid needs to have all joined edges and no naked edges.

Also even if you're not making a solid it can help to identify if there are unwanted gaps in any areas.

- Michael

Okay, got it. And I think I know how many of these occur. When I use 'Blend' and then 'Iso' to make cross-sections of the blended surface, I've found that there are often small errors, where the endpoints of those cross-sections do not quite touch the adjoining edge. When using 'Network', it is essential that all the endpoints of all the cross-sections be exactly on the edges, as 'Network' uses those endpoints and not the actual edges. Consequently, the new edge that 'Network' makes will not quite match the existing edge. The error can be extremely small, but it is still an error. Often, I go to the rather tedious process of resetting those points, i.e. moving each point so that it is 'On' the edge. Sometimes I get lazy and say, "Well, that will be okay", and leave those points as given. I think this is the problem. I will do some checking to see if this theory holds up. However, this opens the door to a suggestion. It would be very nice if there was a way to select two surfaces and have the adjoining edges 'Joined' so as to eliminate these minor errors. It is quite time consuming to go back and regenerate a surface to correct for these errors. And, if these errors are detectable (mathematically), it should be possible to eliminate them -- or so I would like to think!

Hi Tim,

re:
> It would be very nice if there was a way to select two surfaces and have the adjoining
> edges 'Joined' so as to eliminate these minor errors.

The Join command can do that to make a joined edge if they are within 0.005 units of each other.

I would like to make something that adjusts control points but it's fairly complex to do that automatically. Here's an example, notice how one surface has only 3 control points but the other one has a more complex shape than can be represented with 3 points:



So it's not possible to just move existing surface points on the one that's only 3 points across so that it will touch the other surface, it has to be refined with more points. There are other things that can be complex about it as well.

- Michael

I did my experiment. I had one surface that had one naked edge. (All of the surfaces in this model had been 'Joined' and that was not a problem -- I then had one Joined object. 'Details' nevertheless indicated 15 naked edges. So 'Join' did not fix the edges.) This surface looked perfect and zooming in to the limit did not reveal any error. So I completely regenerated this surface by creating cross-sections (with 'Iso'). I moved all the points (26) 'On' to the edges of the adjoining surfaces. Only in the case of one of these points could I see (very close zoom) that it was obviously not on the edge. (However, I've found that any ambiguity when indicating an endpoint, intersection, point, etc. is suspect. After resetting the endpoints, as I typically do, this ambiguity disappears.) I then used 'Network' to make the new surface. Again, it looked perfect. And again, the same edge was shown as Naked. From this I conclude that being aware of "Naked edges" is not useful information, as there is nothing that we can do to correct the errors -- at least if 'Network' is used to make the surface. You point out that two surfaces may have different numbers of points at a common edge. Certainly this is unavoidable. I am given to conclude that this is the cause of a "Naked edge" and if this prevents a joined object from being regarded as a "Solid", then we will have to accept that this is how it goes. If 'Join' results in one joined object, that's as good as it gets.

Hi Tim, if you can please post a .3dm model file with the surfaces you were experimenting with that had naked edges I can take a look and might be able to give further feedback on it.

- Michael