Hi mike,

> Even with "Object-Snapping" enabled and really paying attention when
> drawing curves and making "network-faces", I very often notice, that,
> when zooming very close, that corners/edges of the faces do not match and
> have small gaps.
>
> What can I do in such situations?

It depends on the specific situation, it's actually not necessarily a problem, it's possible that you may be worried about something that's just a display artifact where an area of the display mesh just did not get refined with a lot of polygons, or it can also be normal that corners will not touch each other exactly and that's ok as long as they are within a tight enough tolerance of one another.

It's a normal part of a NURBS model that junctures where many edges come together will have the edges within some tolerance amount of the vertex, not necessarily each one ending exactly on it - many parts of NURBS modeling involves calculations of things like intersections and cuts to some acceptable tolerance level.

It's kind of hard to give you a very good answer without seeing a really specific situation...


> How do I get a "sold" Object?

I'll take a look at your model and see what might be wrong with it. But usually the best thing to do if you need a solid and your object is not a solid is to use the "select naked edges" script as shown here which will highlight edges that only belong to one surface instead of being joined between 2 surfaces:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2

- Michael

Also it's normally ok to export non-solids to IGES format, IGES does support just surfaces alone. If you can't export it then maybe you're running into a bug in the export library, sometimes if there's certain kinds of malformed trimming boundaries the export library can trigger an error and bail out from doing the export. I'll take a look at your model now.

- Michael

Hi mike,

> Tried my second vehicle for Mini-Production.
> This time I cannot export the object as IGS.

Over here I tested loading your attached 3DM model file and then doing a "Save As" into IGES format, which seemed to generate an IGES file ok.

Which version of MoI are you using, are you using v2? If so then I'd recommend using the current v3 beta instead, which you can get from here: http://moi3d.com/beta.htm

It looks like your main car body in this case is made up of 146 individual separate surfaces - these can be written to IGES format, but it is not a bad idea to use Edit > Join inside of MoI to glue together 2 surfaces that you intend should be adjacent to one another. That's generally the easiest way to test if they are actually meeting up closely enough or not, if they are too far apart from one another they won't join.

Also in some spots like here for example there seems to be a duplicated surface with 2 surfaces stacked on top of the same surface area, that's going to most likely cause problems in the receiving application:




It's also better in general to go about building the model using larger extended surfaces that then get trimmed to cut material away, rather than in a segmented "patch by patch" type method like you're currently doing. like the bottom part of the car body would be better if that was one single big surface that had a trim boundary on the outside of it to produce the outside outline, rather than a couple dozen separate pieces that are flat or nearly flat to one another.

- Michael

Hi mike, another thing that you may run into with IGES format transfer, is that usually even when you have a solid IGES files are transferred using a collection of surfaces and then the receiving application rejoins those surfaces together to make a solid. Because of this it can be problematic to have multiple separate parts that touch each other contained all within the same IGES file. It may be possible for the receiving application to sort things out if you have put them on different levels (called "styles" in MoI), but that may not always be supported. So you may need to write out one file with the wheels for example and it may be problematic to have the front bumper which looks like it is a separate object to be in the same IGES file as the rest of the body.

What program are you trying to get this model into by using IGES format? You might try using STEP format instead, STEP is somewhat newer and is usually set up to work with solids so it can tend to avoid some of these issues.

- Michael

Hi Michael,

I tried to "join" the faces several times. But it does not seem to work.
After the "join" command, when I click on the object, it only selects the part/face
where I clicked and not the whole object.

I will go through your posts and see, if it helps.

IGS is requested for production. Get feedback tomorrow, if other formats
are accepted.

I know, that my workflow is not the right one for nurbs modelling.
I come from Polymodelling and sculpting.

With "network"-faces I have massive problems.
When I'm just playing arround, I get the strangest shapes in MOI with
fillets and holes etc. etc.. Everthing seem to work well.
But as soon as I have to work on a concret object/shape (like this toycar) nothing works.
I cannot even bevel the simplest corner. Still have to learn a lot.

A complet car tutorial would be nice!
The ones I found are recorded are all without audio and
so fast, that I cannot follow, whats going on.


regards
Mike

Hi mike,

> I tried to "join" the faces several times. But it does not seem to work.
> After the "join" command, when I click on the object, it only selects the part/face
> where I clicked and not the whole object.

Could you maybe post a file with an example? I just tried with the file you posted before and I tried a few surfaces and was able to join them ok. It's hard for me to give you very good advice when I'm not able to specifically see what you're asking about.


> With "network"-faces I have massive problems.

Is there an example that you have saved off so I can look at it and try to give you some specific advice?

 

> But as soon as I have to work on a concret object/shape (like this toycar) nothing works.

Again, I need more specific information on what's not working for you - for example you said that you can't export to IGES but when I just tried it myself I was able to do it...


> I cannot even bevel the simplest corner. Still have to learn a lot.

Filleting is a pretty finicky operation, there are lots of things that can make it difficult for it to work well. If you could post the file that has this simple corner in it, that may help me to give you some more information on what might be making it to be actually kind of complex as far as filleting is concerned.


When you run into a problem it really helps me if you can post an example file that has things narrowed down just to the specific thing that is actually related to your problem you are asking about. So for example if you're having a problem with 2 surfaces, post a file with just those 2 surfaces in them and not hundreds of other surfaces that are unrelated to your particular question at hand. Please remember that I'm not as familiar with your model as you are and so I don't really know how to sort through a big pile of stuff to get to the thing you're asking about.

 

Car modeling tends to be one of the more advanced and difficult types of modeling you can do... So it kind of requires a longer learning curve and spin up time, you'll be dealing with a lot more difficult areas. It will probably be frustrating for some time to come.


- Michael

You may actually be more productive creating things in your preferred polymodeling environment and then use one of the new crop of converter tools for converting the sub-d model into a NURBS model that can be read in by CAD programs.

T-splines for Rhino can do this, also I think T-splines is built into Autodesk Inventor Fusion now as well, and there is also a converter for Modo called sub-d NURBS: http://community.thefoundry.co.uk/store/Power_SubD-NURBS/

That route may be worth a try for you since you wouldn't have to learn a new difficult and advanced level modeling workflow.

- Michael

Hi Michael,

all told problems occured in this second 3dm-file I have attached.

Good tip btw with Modo and Inventor.
I always thought, that Polymodels could not be converted into nurbs. Only vise versa.

But anyway. MOI is a plessure to work with because of its simple UI and workflow
(except the problems I'm still running into)

So I'm trying to get better skills with nurbs modelling.

Therefore: If I already have the main body of the car (like in my file) how do I make the bottom of the car as
one surface so it fits exactly to the wheel arches?


thanks
Mike

Hi mike,

> all told problems occured in this second 3dm-file I have attached.

Ok, but you have 150 objects in that file and it's not even zoomed in to any particular area. I need things narrowed down a whole lot to have much of a chance at following what you're talking about.

I just looked at your last image shot, and I selected the surfaces around one of your indicated areas:



And that seemed to join up for me ok.

I need to get a much more focused and narrowed down example from you in order to help you very much. It's very difficult to help you given only pretty general or vague descriptions and when I can't reproduce the problem over here. Please be much more specific and give a file with _only_ the things related to the specific issue you're asking about, that would help a lot.

- Michael

> Good tip btw with Modo and Inventor.
> I always thought, that Polymodels could not be converted into nurbs. Only vise versa.

This used to be true, it's only fairly recently that there are some tools for going in the sub-d to NURBS direction.


> Therefore: If I already have the main body of the car (like in my file) how do I make the bottom of the car as
> one surface so it fits exactly to the wheel arches?

The part that goes up to the wheel arches would be separate surfaces, it's all the coplanar or nearly coplanar fragments all along the very bottom that you'd want to have as one big surface. The basic thing is instead of drawing in every single boundary edge of your object to start with, you want several of the boundaries in your final 3D shapes to be generated as the result of booleans or trims between pieces rather than manually drawn...

Car modeling though is a particularly difficult area and there are areas in it that will force you away from the primarily boolean-driven method that is really where NURBS modeling is strongest in and easier to use.

- Michael

Basically NURBS modeling works really well when you are driving much of the design from 2D profile curves, using some of those curves to generate large extended shapes and then using other 2D curves or other generated solids to cut pieces away.

The less that you are able to do things along that pattern, the more difficult things will be and the more things tend to become more suitable for sub-d modeling 3D cage driven workflow rather than 2D profile curve driven workflow...

- Michael

Yes, this is exactly what I have to learn.

I know, its impossible to help me out here with my spare comments.
I for myself cannot reproduce the stages, where I had those problems, but
as you said, I have to think different here (larger shapes and cutting/trimming away)

thanks very much for your support!

Mike

Hi mike, yeah focusing on using cutting operations as a main way of working is usually a big adjustment for people coming from a sub-d modeling background.

Check out here for some links to discussions and general tips for people who are coming from a sub-d / poly modeling background:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

- Michael