Hi.

I've started modelling an AT-AT walker. Attached are .3dm files(both modelled in MOI) and renders(done in Vue6 Infinite) of the foot and complete leg. It's not a completely accurate model so SW fans please don't complain(I've added a few of my own ideas)!

AT-AT plans show some grooves around the perimeter of the circular foot. I would like to boolean these into the foot but I wonder what would be the best way to do this - I can do horizontal and vertical grooves easily enough(just subtract sloping cylinders) but what about diagonal grooves on the sloping surface of the foot? Ideas would be welcome.

Will need to model the body, head and guns to complete the project.


Very much looking forward to the object management tools to make it easier to manage complex models like these.

Cheers
Mal

Hi Medi...

Your mechanical model looks very detail for me. Good !!!
If you create them in sw, I am not surprise. But here you create whole model in MoI. So MoI is used by Mechanical Designer also, not Artist only :)

> Very much looking forward to the object management tools to make it easier to manage complex models like these.
Michael will be work on this stuff soon, be patience ;)

Thanks !

Hi Mal, it's off to a great start, that piece looks nicely detailed already. Looking forward to seeing the whole thing!

re: cutting grooves - check out this post:
http://moi3d.com/forum/index.php?webtag=MOI&msg=817.8
for a technique of projecting curves then using sweep to build pipes for cutting grooves, maybe that method will work for your case as well.

- Michael

(Darth) Mal ;)

I'm really looking forward with your progress. I'm a big SW fan.
I'm also interested in hearing how you incorporate Vue with Moi.
That is the workflow i plan to use very soon. Looks great so far!

Thanks for the comments and advice Michael.

I tried this method and found it works well for curves but not so well for straight lines. If I use a projected polyline on the foot surface and try to sweep a circle I get a number of cylinders corresponding to the lines as boolean objects. Some of these cylinders will work with Boolean-Subtract but others either don't subtract at all or the base object is deleted rather than the cylinders.

Is this a limitation of the geometry library or am I likely to be doing something wrong?

Mal

Hi jiro.

This is the first MOI model I've ever imported into Vue so I don't have much experience with this workflow at the moment.
With this particular model I found that I needed to export it from MOI as a lightwave object(.lwo) with Ngons selected.
I had previously tried exporting it as Quads and Triangles but I found I got small black facets along the bevelled top of the foot at render time with both these exported models.
Ngons export was the only one which properly rendered the foot bevels.
I don't know if this is a general problem or specific to this model.
I just imported the various parts of the MOI model into different layers in Vue e.g. Layer1 - foot, Layer 2 - lower leg etc.

Hope this info is of use to you.

Mal

Hi Mal

> Some of these cylinders will work with Boolean-Subtract
> but others either don't subtract at all or the base object
> is deleted rather than the cylinders.
>
> Is this a limitation of the geometry library or am I likely to
> be doing something wrong?

It's hard to say without examining the actual model file, but if the cylinder/tube type objects are crossing over each other then you're probably running into a limitation of the geometry library where it does not handle the intersection between those kind of shapes that cross at a kind of "crown point".

If you can use a circle of slightly larger or smaller radius for the tubes that cross over another one, that can help solve the problem.

Also another area of difficulty is if the "seam edge" of the tube runs right along the surface to be booleaned. One possible way to work around that problem is to actually rotate your circle around a bit so that the seam edge of the tube is not grazing right along the other surface.

Things like edges that barely coast along another surface or barely graze each other to meet at single points, stuff like that tends to be a lot more difficult calculations for the booleans to process.

If it is possible for you to post the model file that would help a lot in giving some more specific information.

- Michael

Hi Mal,

> I had previously tried exporting it as Quads and Triangles but I
> found I got small black facets along the bevelled top of the foot
> at render time with both these exported models.
> Ngons export was the only one which properly rendered the
> foot bevels. I don't know if this is a general problem or specific
> to this model.

Hmm, that's kind of unusual - normally it tends to be the other way around, with n-gons (especially concave ones with a lot of points in them) can tend to cause difficulty in some other programs.

It may be a bug in MoI's triangulation, or it may indicate that there is something kind of messed up with the surfaces in that area, like possibly a small loop in a trim curve, or something like that.

If you can send me the model file that has the piece of geometry that is giving the black facet problem (if you can just delete other parts that are not related to the problem), that could help me to track down the problem.

Thanks,

- Michael

Hi Michael.

Attached is the foot part model which shows rendering problems around the bevels on the foot.
Also see the attached jpg file with a rendering of the foot showing the black shading problems.


Cheers
Mal

Hi Mal, thanks for posting the file.

Nothing seems to be wrong with the model - your image there looks like the kind of glitch that can happen if a program tries to create smoothing information by averaging polygon faces together instead of using the information directly from the original solid model. In areas around fillets where there are small polygons along side of larger flat ones that kind of averaging does not tend to work well.

If you export to OBJ format instead, then I think that Vue will likely be able to use the smoothing information that is stored in the file (which comes directly from the original model and so is much more exact) and that should eliminate these kinds of shading problems.

So could you please try an OBJ export and see if that gives you better results?

If it does not seem to be better, please try switching the "Weld vertices along edges" setting to the opposite (expand the Meshing options dialog by the arrow in the lower-left corner to see this welding option) - with welding off it makes a somewhat more simple structure to the OBJ file and a few programs will only import the smoothing information when this setting is off (I don't know if Vue is sensitive to that or not).

Also when you import OBJ into Vue, if there is any options that say something like "Enable vertex normals", then make sure that is enabled.

- Michael

Hi Michael

Tried exporting the foot as an object file with welded vertices and then non welded vertices.
See the results in the jpgs attached.
Artefacts are much less but still present in both models.
There are no options to consider normals when importing the models into Vue.

Cheers
Mal

Hi all.

Just an update on the AT-AT walker model.

The motor drive for the legs is included as a 3dm file(MOI) and shown in the jpg(rendered in Vue 6 Infinite).

Now to start on the body.

Any comments are welcome.

Mal

Hi Mal - were those exported using n-gons, or as "Quads & Triangles"?

If it was n-gons, one last thing to try is to use Quads & Triangles with welding off (again with OBJ format).

- Michael