Hi Michael


I know this functionality does not exist in MoI and last time I used Rhino it doesn't exist either.
Once a surface is created, say a swept surface and then trimmed.

Is it technically possible to in some way let the user define how many points make up the surface. If there were less points it would be more artist friendly because there are two many at the moment to manipulate the surface unless you wanted to add a small detail to it. Or could something like 3DS Max's FFD modifiers be programmed into the software. That would then allow the user to manipulate the surface and kind of mould the shape they want. Just a thought anyway. I'm thinking if it had that functionality I could probably mould up the upper surface of the aircraft.

>That is not the only option available - you can also use Construct / Curve / Project to project a curve onto the surface,
>when you edit the surface you will see the projected curve update dynamically with your edits so that could be a
>more convenient system than what you describe here.

That is the answer I've been looking for. That will give me a kind of cross section tool that will allow me to see what shape I will get before I boolean. Hopefully this will also work on the point pulling exercise you showed for the tail section. If it does then I can now have another crack at this project.

Hi Burrman

Thanks for your post.

The reason I started this thread was at Michaels request. See post 20 of this thread http://moi3d.com/forum/index.php?webtag=MOI
He asked if I would show him some examples of the kind of things I was referring to. I decided it might be best to put all those examples in the one thread rather than scattered around the forum.

My agenda with this thread is as follows
1. Create an accurate looking F9F with nurbs and export a mesh out to 3DS Max for texturing and final artwork.
2. Learn more about MoI and Nurbs surfaces.
3. To show Michael some of the problems users face when modelling up difficult subjects which may help him (it may not) further develop the software.

Hi Kevin,

>>My background is Autocad and Inventor which I use all day, everyday at work for past 15 and 5yrs. Both those programs would be totally unsuitable for a project like this or to model up a car. Both are great for architectural and mechanical type work though.

Aircraft/cars are mechanical, so dont quite follow your statement. I cannot comment on "inventor" as I have not used the program, but Autocad, I have used many versions over the years for aircraft and F1/touring car work.

>>At first I tried Rhino V2 and V3 but found getting a a good clean mesh from that program problematical. The problems are mostly bad mesh at the joints between the surfaces which creates shading errors when rendering the model

That is final output and not related to internal construction, and it is mainly construction problems you have posted about.

>>I will be most interested to see your attempt at the model and I appreciate you taking the time to have a go.

Unfortunately I have had no spare time to look at this, but I am unsure of your exact problem. Is it with construction (which should not really be a problem with your use of autocad), or is it just the poly output after construction (in which case whatever method of construction is used, there could still be the poly problem).


- Steve

Some interesting stuff I found if of interest to anyone.
Brian

http://pubs.drdc.gc.ca/PDFS/unc48/p521647.pdf

http://www.google.com/search?hl=en&rls=com.microsoft:en-au&q=Modeling+an+Aircraft+in+Nurbs&start=10&sa=N

http://www.icon.fi/~jtki/3dimens.html

http://ogigi.polsl.pl/biuletyny/zeszyt_14/z14cz3_6.pdf

Hi Steve, thanks for your post.

>Aircraft/cars are mechanical, so dont quite follow your statement.
> I cannot comment on "inventor" as I have not used the program, but Autocad, I have used many versions over the years for aircraft and F1/touring car work.

I'm not talking about using Autocad (or Inventor) to draw up the components of the car as I know both are used for the that purpose all day every day right around the world. I was referring to using Autocad's 3d modelling tools to create the aerodynamic shape of this aircraft and all the subtle blends around the upper part of the fuselage and fin and then converting that model to a nice mesh from Autocad. Autocad's surfacing tools are a little on the primitive side compared to MoI and Rhino.

>That is final output and not related to internal construction
Yes the mesh is a seperate issue and nothing to do with constructing the model in the first place. I suspect Michaels work on the FBX plugin will largely resolve a lot of my past meshing issues especially since I use 3DS Max.

>Unfortunately I have had no spare time to look at this, but I am unsure of your exact problem.
Where I am having problems is creating the blends that are around the cockpit and upper part of the fuselage as shown in the photo of post 63 of this thread.
The rest of the aircraft I should not have any problems with.
What I was hoping you might be able to help with is the best way to tackle this area and keep the blends that are created tangent to one another so that I get nice smooth highlights on my aircraft when rendered.

Hi Kevin,

I'm following this thread, and I understand your filling, I'm coming from more of 10 years of poly/sub-d modeling and I discoverd nurbs this year with MoI.
So far I never had to build something 100% real, so I always find some workaround or 'design' change because I can't exactly get the base shape I want.
In the other hand, as you probably know allready, when the base shape is done, adding all the details is really fun with nurbs, and much more productive than poly modeling.

Maybe you should give a try to T-Spline for rhino and maya. I didn't bought (is that the right spelling ? :P) it yet, just did some easy test with the demo edition. I suppose if I have to build something more advanced with a really organic base shape, I will certainly use this tool. T-spline provide a lot of tool, the best one (for me), is to be able to translate a sub-d cage object into a nurbs version. I don't know if the output quality will be enough for what you are looking for, but maybe it's a solution to help the transition.

http://www.tsplines.com/

Here's for example the modo old guy head in MoI
http://moi3d.com/forum/get_attachment.php?webtag=MOI&hash=b952bf93a30a94269695bbcd2f01caae&filename=wow4.jpg

I don't know howcomplex the technology is, but if one way or an other we can have this kind of feature natively in MoI, (importing a obj cage and get the sub-d version in nurbs) ... that would be realllllly amazing !!!!!!

*edit: Just discovered that Maya allow natively to convert suv-d in nurbs too (I'm only learning it since yesteday :) ... now have to inverstage what are the export format available to get the model in MoI :P

for the old guy is that the process?
Modo OBJ -->Tspline -->Nurbs --> MOI

Hi Paq

Thanks for you comment and interest in the thread. I know there has been a lot of discussion in this thread but I hope there are solutions presented here by Michael that will help people solve some of their more advanced nurb modelling tasks. Unfortunately for me so far on this particular project I haven't been able to achieve what I want.

I had a good look at tsplines yesterday and believe that it would be the best way to tackle the upper part of the fuselage of this aircraft and also give me a nice mesh. It would allow me to kind of sculpt up the shape I need as I am unable to get nurbs to conform to the shapes I need via converntional sweeps and networks especially since surface tangency options are somewhat limited.
Unfortunately the cost of buying tsplines and Rhino for my hobby is a little prohibitive but like you I hope that one day this tool will be standard in nurbs packages as I believe it would be of tremendous benefit in instances like this and many others that I can think of.

>So far I never had to build something 100% real, so I always find some workaround or 'design' change because I can't exactly get the base shape I want.
Yes, I am having similar issues except I don't want to change the design. I want to capture the look as closely as I can.

>In the other hand, as you probably know allready, when the base shape is done, adding all the details is really fun with nurbs,
>and much more productive than poly modeling.
Absolutely, totally agree 100%. It is not much fun cutting out holes, vents and openings in meshes, very tedious work.

Yes Pilou,

I used t-spline for rhino,

So in rhino you import the obj as an sds cage with the tspline plugin (not with the rhino obj import of course), t-spline create a t-spline version of the cage ... then convert it in nurbs, and save it in .3dm.

There was also an tool in the t-spline toolbox you have to use to smooth the blending between every patches. (I don't remember the name)


Now again, until one hour ago, I was thinking that the sds->nurbs was only possible with this t-spline plugin ... but if maya can do it natively, we maybe don't need an alien technology to get the same thing in MoI ... crossing fingers :o)

If of interest
My second go at an aeroplane--all imagined!

Hugely faster than my first effort in MoI but still did some things in silly ways which I would not repeat in a third effort.

Pretty rough I guess--but very, very quick!
Saved to both FBX and ObjN-gons from MoI to use in Carrara.

Brian

Here's a sub-d sphere (aka a box :P), exported in .igs and timmed/filleted in MoI. Need to do some advanced test too :P
Happy me I have to lean and use Maya in my new job :o)

Here's a other try using maya, still thinking it might be a cool way of working ... however there as some areas that are quite
complex (red lines) and need probably to be rebuild/simplify too.

Maybe a little polymodeler in Moi ? :D

Hi all,

Testing some neat stuff there guys.

- Pilou -> Nah Moi is a nurbs and for myself i would love that he stay like that (Michael decide anyway). I have enough modeller with Carrara, Hexagon, Cinema 4D that i added Moi because of the NURBS.

Hi Kevin,

You wrote:
> I know this functionality does not exist in MoI and last time
> I used Rhino it doesn't exist either.
> Once a surface is created, say a swept surface and then trimmed.

MoI does not currently have anything to insert new points into an already existing surface directly, but Rhino has had that function (InsertKnotSrf command) since the Rhino v1.0 release. So that is probably something that you just did not know was in Rhino. That is understandable since there are so many functions in Rhino it can be difficult to learn them all.

I do expect to put this into MoI as well, just the surface control point manipulation toolset has not been a major focus for the earlier versions of MoI since I generally expect that someone who is very interested in pulling surface points around would want to use a subd modeler for that type of thing instead since those programs are totally dedicated to that kind of workflow and are handling that type of thing very well already.


> Or could something like 3DS Max's FFD modifiers be
> programmed into the software.

Yeah, I think that this will be able to happen eventually. But it is not an easy task to make this happen on solids that have joined edges at trimmed surface edges, instead of the natural surface edge of the underlying surface. The latest Rhino version 4.0 has added some various functions to do this kind of thing, so if you want to deform NURBS models with cage editing, you could look into using Rhino for doing that.


Please understand that I only have so many hours in the day to work on MoI. It is just not possible for every single conceivable feature across every single conceivable style of modeling to be added into MoI all at the same time. Many things will take some time to add.


> My agenda with this thread is as follows
> <....>
> 3. To show Michael some of the problems users face when
> modelling up difficult subjects which may help him (it may not)
> further develop the software.

Definitely not a bad plan, and I appreciate the effort!

However, just to be clear, I am already completely aware that MoI's current toolset is not as good for making "point squishing" type editing directly on surface/solid models as you would do in a subd modeler.

It has actually been an intentional design decision to focus priorities in MoI on areas that are not exactly the same as other programs. That can help people get a more well rounded toolset so that they can get more of an expanded toolset when using MoI along side of another program, rather than trying to do a kind of half-effort on duplicating things that are already handled well in your other software.

Over time I do expect to fill in more of the kind of toolset that you are asking about with point squishing, but since it is working well for you in your other modeler, that is all pretty much going as intended currently for the early versions of MoI.

It is the general intention that you would use your other software to do the tasks that suit it better, instead of trying to do those in MoI.

- Michael

Hi PaQ,

Yeah that ability of Maya to transform subd to NURBS does not seem to be very frequently mentioned or used for some reason. But it could definitely be a useful transfer method.


> Here's a other try using maya, still thinking it might be a cool way of
> working ... however there as some areas that are quite
> complex (red lines) and need probably to be rebuild/simplify too.

That kind of smaller patch refinement will generally happen in areas where you have a vertex with a valence of other than 4, meaning more than 4 edges radiating out from it.

Like in this case you seem to have a kind of edge loop that terminates here:



So that created a vertex there that has a valence of 3, and the one right above it has a valence of 5 with 5 edges coming out of it - if you can avoid those where possible then it will probably eliminate that kind of patch refinement.

Like in your case here if you continue that edge loop to the end instead of terminating it, that will probably get fixed up.


There is a common relationship between some of the mechanics of how NURBS surfaces work and how subd surfaces work.

The way that Catmull-Clark subd works, it is actually completely equivalent to a NURBS surface in areas of the subd that have quad polygons with all vertices of valence 4.

Those areas of the subd surface have an exact and natural translation to a NURBS surface.

Areas where that is not the case like at your valence 5 spot, do not have a natural equivalence to NURBS so those areas get processed with a kind of fitting or refinement type scheme to get some NURBS surfaces in there that are close enough to the subd surface. But the refinement will generate additional surfaces, that is what you are seeing there.

- Michael

Hi PaQ,

I see you had another vertex of valence 5 up near the front bottom of the canopy there too, I'm kind of surprised that there was not some additional refinement in that area.

I would be a bit suspect of the surface smoothness in that area, although it seems to look pretty good.

But maybe it just happened to be close enough not to need refinement.

- Michael

Hi Michael,

Maya can only convert what they called 'subdiv surface' into nurbs, so in the image posted, it's the middle model. This model is a conversion from
the polygonal one. The subdiv shape allready shows some complex area in the front of the model, and this seems to be translated into the nurbs model at the end.

I have just no experience about how subdiv actually work, it seems to be way more heavier than catmull scheme. Maybe I should first learn this part to have a better control of the nurbs conversion.

I didn't remember having this kind of result with the t-spline. With the t-spline plugin, the nurbs flow was more looking like the maya subdiv one. (I'm not sure if this sentence is clear enough :P).

Hi PaQ, I see - I'm not really familiar with some of these details on how Maya works, but it appears to me that the middle "subdiv surface" has already been divided down in those valence 5 areas.

So my guess is that a "subdiv surface" in Maya is some kind of hybrid object, which has already been prepared in its structure for converting to NURBS? Something like that anyway.

But if you continue that edge loop that I showed above to the end of the shape in the original polygon model before conversion to "subdiv surface", it will probably simplify that area that you were pointing at with the red arrow above.

You can't always avoid such areas, but in areas that you can it will probably make the result more simplified.

- Michael

Yes I'll give a try with a pure quad model, ... at the moment I'm still learning all the selection and objets organisations tools ... (in other words, I'm nowhere :o)).