Hello dear experts,

I was trying to make a clean surface using Network, (as I saw in tutorials). However, I could not get the desired result with the curves I defined, the resulting surface was bulging and it didn't follow the curves I defined. I am new to moi3d, so I am trying to understand why it behaves that way and what I am doing wrong. Can anyone please explain what I should take into account when making a surface using Network?

Please see the "example.png" and "example.3dm" attached.

Thank you in advance

Is this close enough to what you are after?

If so, what I did is I took one of your side guide curves and trimmed it to the top profile section to break that into two curves. If you turn on POINTS you will be able to see the line that I broke / trimmed or you can click on the segment and you will be able to see which line I trimmed.

Anyhow, after I trimmed that line I then lofted the lower three profiles together. For the loft I also selected to NOT cap it so it is just a surface body.

Then I used a revolve for the top portion of the line that I trimmed into two pieces. When you select REVOLVE make sure that you are doing a RAIL REVOLVE. Pick the shorter, upper trimmed line as the PROFILE CURVE and the top edge of the main loft that you did before to form the initial surface.

Then, for the AXIS start I selected the very top point (I worked with SHOW POINTS on but the snap tool probably works just as well but I wanted to see what I was doing.

Once you pick the first point then move the mouse up in the Z direction and if you have STRAIGHT SNAP enabled when you get close to straight up in the Z axis it will snap to straight up or straight down depending on the direction you go. When that happens click the mouse again to end the axis of revolution selection. the revolve will happen almost instantly.

Then I selected both surfaces and clicked JOIN to make it one object a 'Joined surface'.

I hope that made some sense and I hope it is what you are after.

Hi iv_one, it looks like you're using Network ok - from your initial description I had thought that maybe your curves didn't have a regular grid layout like Network needs.

You have the regular layout, the problem is that you're just trying to construct too much with it and constrain it too much. Basically think of it like applying too much pressure on the result, it's easy for surface interpolation methods to generate undulations when there are several interpolants close together.

It's not so good to try and construct an object that has these kinds of tightly bent corners in it as one single surface:


Tight bends that are transitions between other forms are better constructed as fillets rather than baked in to a single surface.

So a better construction method for that shape would be something like this rather than Network. This is using Loft to build an initial blocky form with sharp edges to start with. Then a curved surface for the top using Sweep, then cutting the blocky base with the curved surface using boolean difference and then fillets on the corners:



- Michael

Basically a single surface like Network is going to generate should be more like a single shape in a broad sheet. If you have tight bends those are transitions between broad sheets and it will be difficult to form them well if you try to "bake" them all at once into a single surface like Network will generate.

Usually it is best for tight bend areas to be done as fillets that transition between separate surfaces.

Additionally trying to use Network to do the whole shape as one single surface will also need a "pole" in it and it can be difficult to avoid visible evidence of the pole structure in the shape as curves collapse down to a single point.

- Michael

Hello Michael,

I hope you are doing well.

I've got a quick question for you. Could we trust and assume a sealed joined surface object as a Solid one (A joined surface object without any open holes)?

And I noticed something! ( I had an object; Moi3D said it is a joined surface I saved the .3dm file as it was and opened it again now Moi3D says it is Solid) which of course is what I needed but it was kind of a surprise for me.

I think I'm starting to understand it better. Thinking about Network like a blank sheet simplifies my understanding and explains why it gets distorted as the shape gets more complex. I will try to approach designing this object differently.
Thank you very much!

Hi Psygorn,

re:
> I've got a quick question for you. Could we trust and assume a sealed joined surface object
> as a Solid one (A joined surface object without any open holes)?

There are actually 2 conditions that MoI checks for to give an object the designation of "solid" - that it has all joined edges and also that it has at least 2 volumetric regions in it.


> And I noticed something! ( I had an object; Moi3D said it is a joined surface I saved the .3dm file
> as it was and opened it again now Moi3D says it is Solid) which of course is what I needed but
> it was kind of a surprise for me.

There is probably some kind of anomalous geometry in the object like a degenerate face that is squished flat like a line or areas of the model that self intersect. Such things can cause inconsistencies in volumetric analysis for determining regions.

- Michael

Hi Michael,

I hope you are doing well,

Thank you for your reply.