Thicken (shell) accurately?

[Playdo]

I'm using 3ds Max but a technique from anywhere should work.

I need an accuarate way to thicken a surface. When I use the shell modifier, the results aren't as clean as I need. I think it's due to the direction of the normals for individual polys (I've checked ' straighten corners' too). I'm trying to get a uniform and straight shell. I've tried copying the surface and applying a push modifier but I'm getting the same results.

How should I be tackling this for the best results?


Shell 01.jpg

[Duron]

Try extrude with 0 Height.. and transform it to the direction you want by hand. otherwise shell is best solution for me.

[Playdo]

Hi Duron. I don't think moving it by hand would work as the surface is curved (scaling it inwards may). Do you know what is causing the shell to do this and how I can prepare the surface (before shelling) to prevent it?

[Duron]

I dont know what you want, pls explain better

i used for the left one, simple extrude with 0 height and moved the polygons by hand in one direction.
for the right one i used shell modifier

[P2sta]

was fighting with this problem too, but didn't find any good solution...so I just use shell and then get it right by hand

[Playdo]

I want it to thicken in the direction of the surface's normal, evenly. So the profile doesn't change (see image)

eg instead of shelling each polygon in the direction of it's normal, which is messing my original curves up

Shell 02.jpg

[Playdo]

P2sta. I'm thinking that there might not be a solution but I'm playing about with it at the mo. I've got it clean by extruding the faces as a group, then scaling in one direction. Now I just need to figure out how to scale in the other direction correctly to keep the profile.

[Duron]

If this is what you want, you can use Bridge now to connect each edge and you have the thickness you're looking for, maybe

[Playdo]

I got that by scaling inwards in one axis. I need to figure out how to scale it correctly in the other axis now. Any ideas?

Shell 03.jpg

[DaveCox]

Wait - wouldn't you just select all polygons and then extrude then cap and connect the boundary?

[Playdo]

No, it's to do with the direction of the individual polygons' normals. I can't seem to get it when scaling in the opposite direction either as it changes the profile. I'd need to keep the front faces where they are and move the back faces inwards, but this alters the curve.

It looks like the surface needs to be duplicated and the verts moved manually and aligned. I want to get nice accurate corners as it's for close up details (the mesh is quite dense). Painful.

[EquiNOX]

Shell Mods is the best way like everyone say... Alternately you could try several things before adding shell mods:

-Hit Reset Xform and collapse the geometry under modifier list
-Convert from Poly into Mesh then again Convert into Poly.
-Remodel surface and get this correct.

There are times strange things can happen to geometries after modifying... first two steps above could sometimes help reset poly normals or edge directions

Hope that helps.

[Playdo]

Hi Equinox. I do reset Xform and collapse the geometry. I don't think that's the issue here though.

"Remodel surface and get this correct"

Can you explain what you mean? You mean remodel the surface before aplying the shell modifier? If so, how do I model it correctly - What am I aiming for?

I nearly got good results by: cloning the surface, scaling it in one axis, then I needed to use an FFD modifier to scale it in the other axis whilst keeping the front edges where they are. The problem was, in Max, the FFD modifier doesn't work, the Set Volume and Deform: All Vertices don't work, so I couldn't keep the front edges in place. Anyone know of a workaround to get FFD working, or a plugin?

[Duron]

Yes, i wanted to mention FFD modifier, which i often use.

As you can see, there is not a easy way to get it like you want, you have to plan your steps like when you add modifiers etc. but its not impossible.

[Playdo]

So is that what you do; copy the surface, scale and then use the FFD modifier? I'm having problems with the FFD modiffier (as mentioned above) - I can't get Set Volume to work.