Hi danny !

Thanks for your enthusiasm ! It's a pleasure to get some external feedback and you apprently rock at modelling !
And all your mod matches quiet perfectly the "blue print" I joined, that's insane :D

However, as you told me to feel free to ask for anything : It would be great for me and for other users to see precisely the workflow you've used to build the "boiteaproblem" :D
I mean if you've got a bit of free time (I know it can be time consuming huhu) if you could take some screenshoot along the way it would be REALLY nice :D

PS: I guess you've used v.2 beta ? Because I've got the v.1 (...) ^^
EDIT: Pilou's right, what about the glitch ? Is that okey for rendering with Mental Ray back into 3dsmax for instance ?

This glitch for rendering is nothing ;) (not visible)
It was just for the perfection :D

Thank you Michael for providing explainations and examples for problems like these, I learn so much about modeling with MoI from these kinds of posts - especially since these are very common problems for a lot of the modeling I do.

If possible, please consider collecting up these tidbits - especially the GIFs and create perhaps a Troubleshooting / Best Practices wiki area or perhaps a section in the User's manual or a seperate manual on tips, troubleshooting and best practices. ;-)

NURBS modeling is IMO, way easier than SDS, BUT if you don't know how to troubleshoot your objects (especially the way you do), it still makes it hard to become successful creating the shapes you desire.

Posts like these go beyond teaching you how to use a particular function within MoI, they teach you solutions and techniques which a lot of times you just don't learn from reading the docs on the individual tools themselves...


-Will

I agree. And if I'm succesfull Ill make a full tutorial speaking about tips and tricks I've discovered throughout this post thanks to MoI users and it's creator ;)

.

Hi,
My solution to fileting issues to to try and remove the seame edge from the area that has problems. So MoI will produce the same result as the ViaCad Model if you can eliminate that seam edge in the top surface:



My method was to replace the point in the profile of the part. I could either "RebuildCurve" or "Add Point"



My question regarding "Add Point method, is how to get the point added to be the same distance from the point to be removed on both sides? I could, for this model just copy or mirror, but in the case of to different sides, I couldnt do that. Trying to keep both of those the same through the add point/remove point op. (The other side meaning the opposite side of the model)






Also, what is the best "position" for the 2 points added, to try to maintain the original curves shape?

If this is not clear question, let me know and I will illustrate better.

Thanks,
Burr

Also, in regards to the output looking just like the ViaCad one, looks like they may have a mechanism to ignore those inside surface boundries? I wonder if the geometry guy's have been looking at this? (Yeah right, Burr knows what they dont know) Anyway....So maybe if there is an explanation as to why ignoring those interior surface boundries is bad, then that situation would have the ViaCad filet'r fail? Or the hard part is writing the "ignore interior Surface boundries" part.

Hi Anthony,

> It would be great for me and for other
> users to see precisely the workflow
> you've used to build the "boiteaproblem" :D

No problem, as soon as I have a chance I'll post a few steps.

> Pilou's right, what about the glitch ?
> Is that okey for rendering with
> Mental Ray back into 3dsmax for instance ?

Looks like Pilou has answered that already, I was actually quite pleased that MoI got that result, otherwise I had to resort to low level modeling where you seperate the surfaces and start trimming and joining, which involves a pretty high degree of accuacy and time to get things to join up again, anyway, that area will be covered by the knurled ring as well so for rendering I don't think it will be an issue.

Cheers

Hi Will,

Actually, there is already a section in the wiki for that, it's the tutorials section here:
http://moi3d.com/wiki/Resources#Tutorials

That's essentially all that a tutorial is - an illustration of best practices and a solution to a specific modeling problem.

That tends to be the best way to illustrate things, because it just does not work very well to try and discuss the "best practices" in isolation, it tends to make more sense when you see them in action working on a particular model, which is a tutorial.

Over time I do intend to add additional tutorials, I hope I will be able to do some additional ones when I switch focus to documentation after the last v2 beta is complete.

- Michael

Hi Ed,



Yup, that is a good way of thinking about it.

It tends to be difficult for people who come from a background of polygon modeling to think in this way (initially at least), because trimming/cutting/boolean type operations do not really work well in a polygon modeler so they have trained themselves to avoid them at all costs.

In NURBS modeling booleans tend to be the #1 way of getting things done instead of something to avoid. So that's a pretty big shift for someone with that kind of background.

- Michael

Hi Burr,

> My question regarding "Add Point method, is how to
> get the point added to be the same distance from the
> point to be removed on both sides?

Sorry, I'm not sure if I totally understand what you are doing there, but there is an alternate mode for "Add point" which will kick in if you do not have the control points for the curve turned on.

When you have control points turned on, when you use "Add point", it will snap to points on the control polygon hull, this is the "Add control point" mode.

If you have control points turned off (or if you manage to find a spot on a curve that is not nearby a control point hull when they are turned on), then when you click on a curve it will insert a point in "Add knot" mode.

When you add a control point, the other control points of the curve remain in place, and the curve may shift in shape a bit.

When you add a knot, it is the reverse - the control points of the curve will shift around a bit but the curve's shape remains 100% identical to its previous shape.

So if you want to fuse segments together but maintain the shape closely, you can do that by adding knots to either side of the join point and then go in and delete the control point at the join, that should minimize changes in shape to the curve.

In the future I do expect to add a more direct way for fusing curves together into single segments.

- Michael

Hi Burr,

> Or the hard part is writing the "ignore interior Surface boundries" part.

Yeah, more or less it's this part - it's not particularly easy to pretend that 2 surfaces are just a single surface, each surface usually has a different UV parameter space layout to it and stuff like that, things that operate in parameter space are not easily adapted to span multiple surfaces just automatically, it takes special consideration to do it.

- Michael

Did I "add Knot"?....Not. Will I add Knot in the future?...No....NOT! :O (Sorry,. Couldnt resist)

Thanks again.

Hi Michael,

> I do hope to get at least some improvements to filleting
> for v3 though, but it depends on how much time is
> invested in it by the company that makes the geometry
> library that I use - the fillets in MoI come from a
> geometry library that I license, I did not code that
> part directly myself.

I had a look at Integrity ware and their white paper on filleting and it looks pretty capable, so they claim and show, is MoI eventualy going to implement most of these filleting features?
I'll have to try some of their examples as a test to see if I get the same result ;)

Cheers

Cool varieties !

Hi Danny,

> is MoI eventualy going to implement most of these filleting features?

It should be already, as far as I know... aside from variable radius filleting which I will need to cook up an interface for at some point here.

It's easy to get a kind of wrong overall picture just by looking at a few examples though, much of the difficulty in filleting involves handling a myriad of special cases like many different corner configurations and that only really comes with a large investment of time to handle each kind of thing on a case by case basis.

One thing that I don't currently specifically enable in the IntegrityWare engine is the option to do a piecewise or global merge of the fillet surfaces, which kinds of booleans them into place I guess rather than having them trim into place.

I guess it is possible that could help with a couple of specific cases, but it also seemed to slow things down by quite a bit so it did not seem to be automatically "better" to do it in all cases.


For the most part, I think that filleting problems come from corner configurations that are not handled, not continuing a fillet across the seam of a closed surface (which seems like it may have worked in some cases in the past but is not working 100% anymore) and difficulties with getting a clean intersection between 2 extended fillet surfaces in near tangent conditions.

Of these, I'm hoping that the "crossing the seam" case may be the best potential to try and focus on getting fixed later. That seems to be the most common problem, so if it can get fixed I think it would be a pretty major gain.


- Michael

Ok, so my goal is to relace these points here in green, with the smallest amount of change to the curve in red. (arrows that is)



It was my understanding that you would need to place a point on either side of the existing point, as close as possible, to keep the curve from changing. So I zoom in, and can place my points very close.



But I cant place them "Exactly even"...For either side of the point needing deletion, and for the opposing curve that I want to do the same to. I would want the 2 curves to be the same, and not slightly different.



It's a darn "Conic Curve" again! :O

Hi Burr,

> It was my understanding that you would need to place a
> point on either side of the existing point, as close as possible,
> to keep the curve from changing.

Not necessarily "as close as possible", just fairly nearby it.


> But I cant place them "Exactly even"..

That's ok - it probably doesn't matter that much if they are exactly even or not.


> I would want the 2 curves to be the same, and not slightly different.

Well, if you're going to delete a control point, the result is not going to be 100% completely identical. But if you placed additional knots just fairly close to either side of the place you want to delete, the final curve you get with the deleted control point is going to be very very close to the original one.

When you say "not slightly different", do you mean you do not wish to allow even a 0.0000000000001 difference between the curves or something like that?

If you are really concerned about it for some special reason, place 2 or 3 knots to each side of the one you are going to delete, that should reduce the change to the curve even further when you delete the point.


Probably the easiest thing is to use the new Rebuild command that will be coming in the next beta - it will allow you to specify a tolerance level for how accurate the rebuilt curve hugs the original input curves, and it refits any segments that are tangent to one another as a new single segment automatically.

I've attached the results here of running Rebuild with a tolerance of 0.01 .


At some point I also want to probably update the merge command to maybe make it work to merge tangent segments into larger segments without rebuilding, but it is not yet clear to me if merging lines and arcs together into single curves is a good idea or not.

- Michael

Thanks Michael,
I didnt mean the .00000000001 thing. I just experienced that if the curves were different at all, that the swept surface had wiggles. Since I was sweeping it to a point there. I ended up using RebuildCurve to get my result, but I added about 80 points to be sure that that tangent area where the conic meets the line segment was true. I thought there was something I didnt know about how to delete that one point properly to get exacting results.

I've been using rebuildcurve alot lately and the new command sounds very cool and powerful. I cant wait to see it! (50 bucks to send it to me now) hehehe!

I didnt think of just putting in more knots. Good advice. Thanks for the time, more in my toolkit,
Burr

Hi Burr, yeah every time you add in an additional knot in that area, it will reduce the stretch of the curve that is affected by the control points in that part of the curve.

The new Rebuild command has 2 modes to it, a "Refit to tolerance" mode where you give it a distance value, and it refines the rebuilt curve to use as many points as necessary to achieve that tolerance, or a "# Points" mode where you just tell it how many points you want it to use, that mode is like the current RebuidCurve plugin.

- Michael