Is there any way to remove an "edge" from a sphere? I am playing around getting a good feel for MoI and Keyshot, but for the life of me I can't figure out how (if I can) remove this edge. Is there an export setting that will remove it?

Thanks for any help,
Nick

Nick,
I don't get that edge appearing when I import a simple sphere from moi. I am exporting an obj from moi3d ('only triangles') using the default settings (ie.don't change anything) when I import into Keyshot. When I do this it appears as you want-without the line.
HTH
possum

Hi Nick - that edge is what is called the "seam edge" of the sphere, and it is a built in and natural part of the surface so it's not something that you can remove.

The surfaces in MoI are called "NURBS surfaces", and the way that these kinds of surfaces work they are defined by a quadrilateral mesh of control points. So every surface is actually internally a 4-sided thing.

So you can kind of imagine that each surface is kind of like a 4-sided sheet of paper, only make a kind of stretchy rubber paper.

A closed surface like a cylinder shape is formed by "rolling" the sheet of paper into a tube so that it has 2 opposite sides of the paper touching each other - that's what is called the seam edge.

Then for a sphere the top and bottom edges are collapsed down to a single pole point.

So anyway that edge is just a fundamental part of how a NURBS surface is defined, it's not something that can be removed.

But when you export to OBJ format, that edge is not going to show up in the rendered result, because MoI exports vertex normals to OBJ format which controls how each polygon is shaded. Those vertex normals come from the NURBS surface, and because the sphere surface is tangent to itself in that seam area, it will render without any visible crease and will shade exactly as an edgeless sphere in those areas.

If I remember right, the only thing you need to worry about is that KeyShot does not like to handle n-gon polygons so when you export from MoI make sure to use the "Output: Quads & Triangles" or "Output: Triangles only" option instead of Output:n-gons.

- Michael

One thing to remember about that seam is that if you use a sphere in boolean operations, rotate the sphere first so that the seam is in the part that is cut away. Otherwise you will transfer the seam to the resulting object. You can't get rid of it, and it can cause problems further down the line. This also applies to cylinders.

Ah hah... Thanks everybody. Unfortunately I only have the crummy limited Alibre version of Keyshot... :-( So I have to import into Alibre and then export to .bip Alibre doesn't do obj format... I guess I have to redraw the sphere and put the lettering on the non-seam side... I was wanting to use this to create and view my own keyshot materials since the included library is very limited.

BTW-I was actually thinking the sphere was created from a revolved arc.

Thanks,
Nick

Hi Nick,

> So I have to import into Alibre and then export to
> .bip Alibre doesn't do obj format...

It depends on how Alibre generates the .bip but it's fairly likely that they'd export vertex normals in a similar way as MoI does to OBJ format, so probably the seam should not show up with that method either if they are generating the .bip in a good way.

Are you actually seeing the seam in KeyShot when use the MoI to Alibre to .bip to Keyshot method?


> BTW-I was actually thinking the sphere was created from a revolved arc.

Well, that's true too - the sphere is equivalent to a revolved arc. But a revolved arc will still create the kind of surface that I was describing, it will have a quadrilateral grid of control points with the top and bottom edge collapsed to a single point (that's where the arc would touch the revolve axis) and with the other 2 edges touching at the seam.

- Michael

Yeah, they show up in Keyshot. Some materials hide it better than others.








Thanks,
Nick

Hi Nick, well that's too bad - it would be possible for that to be avoided if the Alibre .bip export would output vertex normals to the .bip file that they generate. It's kind of surprising that they don't do that, since you get a much higher quality smooth looking shading when that is done. Not just for sphere seams but it would improve shading and reflections in quite a lot of other areas as well.

You might want to look at SimLab Composer:
http://www.simlab-soft.com/3d-products/simlab-composer-main.aspx

I believe that SimLab uses the same KeyShot render engine, but it can import OBJ files, and I think it can even generate .bip files as well. It's not too expensive - $149 for the rendering edition, and it sounds like the less expensive $99 PDF generation version may still have the export to .bip that might work better for you (you could go export from MoI to OBJ, then OBJ to .bip using SimLab and then .bip into KeyShot, maybe with vertex normals intact all the way hopefully). I think they have a trial version that you could test with.

- Michael

Looking at those renders, there could be two reasons that the seam is visible. One is that the vertices are not being welded when they are exported by Alibre, resulting in duplicate edges along the seam, or, more unlikely, a deliberate Phong break is being applied to that edge. Either way, the Phong smoother is stopping at that seam. Somehow, you have to weld all the duplicate vertices so that there is no obvious break that the render engine can see.

Hi Steve - so ideally the export to the render engine would include vertex normals coming from the original NURBS surfaces.

Usually if vertex normals are supplied render engines will not do any kind of phong smoothing of their own with break angles where welding or not having welding is significant - those are all methods that render engines use to cook up vertex normals from plain polygons that did not have any vertex normals attached to them to start with (which could be the case in various situations like if you're creating polygons directly in a polygon modeling program or something like that).

That's what's so great about getting vertex normals to come through from the original CAD model - because when it does you don't have to worry about any of those kinds of phong smoothing / break angle / welding type issues... If the NURBS vertex normals come though it means the polygons will be shaded to look the same as the original NURBS surface even if they're completely unwelded with every single polygon unconnected to any other.

- Michael

I ended up just re-doing the sphere.


I did have a hell of a time getting the lettering booleaned to the sphere.

Is there an easy way to do that?

The steps I used:
(used keyshot logo eps for lettering template)
1)project letters to sphere surface
2)get center point of each letter and the sphere
3)extrude each letter by selecting direction from sphere center to letter center
[This is where the problem comes from. The projected letters only extrude as surfaces.]
4)create new sphere slightly larger then original
5)boolean merge both spheres and letters. (I now have solid letters that follow the sphere curve)
6)draw new sphere same as original size or slightly (1/64") larger
7)boolean union each individual letter with the sphere (if I try to do all of the letters at once it either fails or has voids and will not create a solid)

This process after the projection takes several tries to get good results.

Hi Nick,

Please make sure, you have the current version of
- Alibre Design V2011.0.0.60 (32 or 64 bit)
- KeyShot 2.2.45

Alibre settings:
- File -> Properties -> Display -> Minimal Circular Facets: min. 36 --- max. 64 -> F5 -> Save


KeyShot 2.2.45
- File -> Open -> ....KeyShot -> Scenes -> keyshot_bal.bip

Screenshot: keyshot_bal.bip

Hi Nick - re: booleaning letters on the sphere - from what you wrote it sounded like you were projecting curves, then extruding the projected curve? You'll end up with a non-planar curve that way and extruding a non-planar curve will not produce end caps because the curve extruder only knows how to put end caps on planar curves.

But if you use Trim to cut up the sphere surface by your curves, you can instead extrude those smaller surface pieces, and extruding a surface will always result in end caps even if it is non-planar because the extruder knows it can just make a copy of that surface on the other side to cap it off.

So if you do it that way (extrude surface pieces rather than curves) you'll have solids after the extrude and you won't have to do some of your other steps after that.

Another tip - you may want to use the Shell command on those surfaces to thicken them up rather than extrusion - the shell command can take a surface and then produce a thickened solid from it and you don't have to set any direction for it because the it's created by surface offsetting where it follows the surface normal of the starting surface.

See here for an example image for Shell:
http://moi3d.com/2.0/docs/moi_command_reference7.htm#shell

- Michael

It looks like Alibre is either not exporting the vertex normals properly or is not treating the sphere as a solid, closed surface. If the sphere was imported from MoI might there be another step in Alibre to close the surface? Join tolerances might be different?

- Moi3D
- Export -> STEP
- AD -> Import
- AD -> Export -> *.bip
- KS -> Open

In French I read MOL = Flabby :)

So it's better to write Moi = Me ;)

Ralf-
Are you suggesting MoI>STEP>Alibre works better than directly importing .3dm files into Alibre?

I might just have to hunker down and learn 3ds MAX (I won a license, but have never previously used it...), my limited MAX skills have shown better import results, especially with the direct .fbx out of MoI to MAX.

Well, I should learn MAX anyway...

Nick-

Alibre can not import *.3dm files.

Import/Export
- MoI3D <-> AD you can use: STEP, SAT, IGES

Yes it can (at least mine can). Alibre labels it as Rhino for some strange reason...

Nick,

Probably you have installed an Add-on?

3DM Import for Alibre Design - Rhinoceros 3DM file import add-on for Alibre Design
http://www.sycode.com/products/3dm_import_ad/index.htm