Subdivision

[Willy]

I have been learning to use subdivision in modeling. I'm starting to like it a lot.

http://www.citlink.net/~ckearley/WillyAC3D5Subdivision.jpg

[nightoftheroundtable]

thats pretty nice looking I to enjoy the subdivison tool. but if you haven't figured it out do not try and subdivide your model more than 3 times well it all depends on how big your model is. I have found that if you subdivide more than 3 times it could cause AC3D to Lag. Could that be some sorta bug in AC3D

[Willy]

It's not really a bug in AC3D. It's that there gets to be so many polys that it slows down the program and machine trying to render them. For the type of models shown in the picture I try to keep them under 4000 polys and preferably much less.

It depends on what you want though.

[nightoftheroundtable]

hey willy did you check out my projects yet they include subdivision check it out

http://users.techline.com/drreed/index23456789.htm

[Willy]

Yes, I saw your models. Very nice. While looking at them it brought to mind a question I had about the models I was working on. I can reduce the poly count on the models by combining surfaces manually. Some of the surfaces lie on the same plane and unless there's a special reason not to they can be combined into one surface. I'm wondering if there is a way to automate that process. Not just with surfaces that share the same plane but perhaps with surfaces that join at an angle that is equal to or less than one that is user defined and if they could be combined with a smoothing algorithm which averages. Just a thought. I wonder if Andy is reading this thread.

Or if any of the plug-in scripters are, and what they think of the idea?

[nightoftheroundtable]

well I was wondering about the vertices, cause when you select more than one vertice and the press the C command which combines the surfaces I have noticed that there are still the orginal vertices there. my question is now what can those left over vertices do what purpose do they still serve.


ooh and just a little f.y.i willy my car models all started out from one polygon

[luuckyy]

Yes, I saw your models. Very nice. While looking at them it brought to mind a question I had about the models I was working on. I can reduce the poly count on the models by combining surfaces manually. Some of the surfaces lie on the same plane and unless there's a special reason not to they can be combined into one surface. I'm wondering if there is a way to automate that process. Not just with surfaces that share the same plane but perhaps with surfaces that join at an angle that is equal to or less than one that is user defined and if they could be combined with a smoothing algorithm which averages. Just a thought. I wonder if Andy is reading this thread.

Or if any of the plug-in scripters are, and what they think of the idea?

Did you try the reduce fonction in the object menu ?
I don't know how it works, also never tried it ...

[luuckyy]

well I was wondering about the vertices, cause when you select more than one vertice and the press the C command which combines the surfaces I have noticed that there are still the orginal vertices there. my question is now what can those left over vertices do what purpose do they still serve.

First select 2 surfaces, combine them, and then delete the useless vertices if any. AC3D won't do that job for you (indeed it's up to you to decide if these vertices are really useless or not).

[nightoftheroundtable]

thank you luuckyy

[DRAKELOT]

Looking good my friend !!!

[nightoftheroundtable]

who models are looking good mine or willys?

[Willy]

Here's a new pic of the same spaceship.

http://www.citlink.net/~ckearley/WillyAC3D5Subdivision2.jpg

Spaceship: AC3D/Povray

Planet: Bryce

Compositing and Editing: PaintShopPro

It's my first try with the planet...

Anyone know how to get a backdrop like this into Povray using AC3D? Is it possible?

[nightoftheroundtable]

hey will thats pretty nice. I was wondering do you a have any tutorials or have any ac3d models of that ship cause I was wanting to play around with it and see what I could do.

[Willy]

I don't really have a tutorial except for this.

Make a simple primitive model then choose it as an object
then go to the object menu and choose "Subdivide once".

If you are not seeing something you like then UNDO and adjust
the primitive model and repeat the process until you have a shape
that you want to continue with.

After you've made any changes in the model after subdividing once
then you can subdivide it again and see how it looks at the higher
subdivision level. You keep doing that until you're happy with what's
on your screen.

I admit that I'm ignorant and don't know what the "commit subdivision"
option really does or why it is necessary. I've never used it.

Since sometimes I'm not sure whether I really want to keep something
as a final design I have bunches of .ac files of the same basic design at
different levels of design and subdivision. That way I can go back to one
if what I am working on doesn't work out.

For example, I had about a dozen different versions of this spaceship
model saved but only one version that was primitive with no subdivision at
all and here it is:

http://www.citlink.net/~ckearley/BoP01.ac

Please note that after you subdivide a model there are more polys present
which you can manipulate and fool with in order to tweak the model. But
those changes go away if you decide to UNDO back to a lesser level of subdivision.

Let me know if you need more info.

:EDIT One other thing. After you subdivide this model twice you are probably going to have more than 3000 polys.
That's plenty for most applications. I wouldn't subdivide it again unless there was just no other way. You can set the
crease angle to 180 and smooth the polys and it will look quite good at less than 4000 polys in most cases.

I can't wait for the new version of AC3D to come out so I can learn more about subdivision. I have many questions.
Like how is the best way tohave a lot of polys in the highly detailed areas where they are needed and not in the
rather simple areas where they aren't needed. I hope the new docs give that kind of info.

[Willy]

Also VERY IMPORTANT!

I forgot to tell you. Your primitive model does not need to have any internal walls or anything like you'd get if you just set two boxes side by side and merged them into one object. If you are going to do that then the walls where the boxes touch each other need to be removed first before merging.

In other words, your model needs to be completely hollow with no sufraces inside except for the inside of the surfaces that are on the outside. :)

I hope I made that clear.

[Willy]

Here's a different Spaceship primitive model for you to look it. It's somewhat similar to the first one but has some different stuff I tried that worked out okay. Also note that there are apparently two bad polys in the primitive version that subdivision apparently corrects. I'm not sure how that works.

Anyway, it's worth looking at.

http://www.citlink.net/~ckearley/NewShip01.ac

[nightoftheroundtable]

okay thanks I know this might be noobish of me to ask but how do I put it in the code into AC3D.

[Willy]

If everything went well it's a complete AC3D file. All you should have to do is save it to somewhere on your harddrive and then open AC3D and open that file as any other AC3D file.

Let me know if that doesn't work because it would mean that something has gone worng.

[nightoftheroundtable]

it says milkshape import failed

[Willy]

Okay, you got me.

Using firefox I clicked on the link I gave above and chose "Save Link As" and then saved it to a folder I just created. Then I opened AC3D and did a "File -> Open" and went to that new folder and double clicked on the file and it loaded fine.

I have not a clue as to why AC3D would think it was trying to import a MilkShape file. Unless the file name or extention got corrupted?

Any help here people?

[nightoftheroundtable]

ooh my bad it does work I just clicked it with my left mouse instead of right clicking

[nightoftheroundtable]

ooh yeah thats a nice looking ship willy do you care if I modify it

[Willy]

Feel Free.

Please post some pics so we can see.

[nightoftheroundtable]

okay will do post pics on my website when I get anything done if you have any more ship models like that I would be happy to see some

[Willy]

Here's a sci-fi aeroplane I did tonight.

It's not much but it shows a couple of new techniques.

http://www.citlink.net/~ckearley/Plane01.ac

.

[nightoftheroundtable]

one question how can you make all these planes with just one box the main thing that I can make planes out of is spheres, any tips on how to make the planes with a four sided cube. obveiesly I know about dividing an object but when I tried that I can't move any :( any tips

[nightoftheroundtable]

ooh I uploaded a pic of your plane that you let me modify I'm still working on it let me know what you think of it.

its at the bottom of my page

http://users.techline.com/drreed/index23456789.htm

[Willy]

That is some mighty big fins on that airplane. :)

As far as box modeling goes I use primarily the box primitive and extrude surfaces and ident (surface menu). I do not use divide because I could never get the hang of it and I don't like the way things subdivide after being divided. If I really need to divide a surface I usually use the knife tool.

You can use spheres to model but that's more traditional modeling rather than box-modeling which imo is what subdivision works best with.

The whole idea of box-modeling and subdivision, as I understand it, is to lessen the workload. Once you get the hang of it the subdivision routine does most of the rounding and smoothing work. Work you'd have to do manually using spheres and other organic shapes and manipulating the surfaces and vertices individually.

Subdivision won't do all the work. But once you get the hang of it you can design a basic shape made out of box type geometry and then subdivide it a couple of times until you see you have a shape you want to work with. Then you can undo and go back to the first level of subdivision and manipulate surfaces and vertices by hand, occaisionally subdividing again to check your work. Then when you are happy with what you have you can subdivide a final time. After that you have the option to manipulate surfaces and vertices again to finish the detail.

I think the whole purpose of subdivision is to save you time. Once you get the hang of it you can make a primitive box-model which subdivides into the shape you want. Thus saving you a lot of work. Then you can add detail manually. I'm sure subdivision is not good for every modeling task but so far I like it.

[nightoftheroundtable]

hey on the subdivison rule can you subdvide surfaces or is it just one object at a time. and I'm glad you like the improvements

[nightoftheroundtable]

ooh okay now I see how you made that ship without dividing the polys lol took me just now to figure it out. is there any more useful tools for ac3d

[Malekovits]

The "new ship01" Very nice (subdivide x3 and then commit subdivision).
Very very nice!!! :D

[Willy]

Thank you.

I'm ignorant. What exactly does "Commit Subdivision" do, anyway?

What does it accomplish?

[Malekovits]

Subdivision, I thing, divides (a rectangle becomes a scuare made by 4 smaller scuares) and smooths.
Check out my subdivision:
http://img.photobucket.com/albums/v327/Malekovits/spaceship1.jpg

http://img.photobucket.com/albums/v327/Malekovits/spaceship1wire.jpg

http://img.photobucket.com/albums/v327/Malekovits/spaceship1non.jpg

http://img.photobucket.com/albums/v327/Malekovits/spaceship1nonwire.jpg

[Dennis]

It actually sounds like Willy is wondering about the "commit" part.

When you subdivide an object, it adds to the existing geometry and smooths the entire shape. You can add/subtract subdivision levels to increase/decrease the amount of added geometry and smoothness in an object.

By "committing" subdivisions, you are telling AC3D to permanently convert the geometry to using the current subdivision level. Once committed, you cannot decrease the subdivision level. (of course, you can apply further subdivision and increase/decrease that as needed).

Hope that helps.

[Malekovits]

Aaaa! The commit...
The simle subdivision is just making a preview.
The commit converts (as Dennis says) the preview to a geometry.

[Willy]

I believe I understand now. I had, of course, noticed that when a model is saved after being subdivided it could no longer be reduced back to the original primitive after reloading the file. In effect, the subdivision having been commited by the saving. Do I have that right?

What I really didn't understand was the point of setting subdivision levels in the objects property settings. And I was wondering if I was missing something important, some bit of knowledge that was passing me by.

All I'd been doing is modeling then subdividing then reducing the subdivision level and making changes until I was happy with the result. Then I'd simply save the model in the most primitive state I could unsubdivide it to without losing detail.

I guess I still don't understand why there is the facility to set subdivision levels in the properties. I'm still wondering if I'm missing something.

[luuckyy]

I guess I still don't understand why there is the facility to set subdivision levels in the properties. I'm still wondering if I'm missing something.

It's only for quick preview purpose.
If you are making a model which will be subdivided after your low-poly work, with a defined subdivision level and by pressing the "d" keyboard key, you have a preview of your "future" model.

[Dennis]

Subdivision also has the added benefit that you can manipulate fewer points on your model. If your model has 20 vertices in its raw state, it will have 300+ vertices when it's subdivided twice. If you leave it uncommitted, you only have 20 vertices to manipulate when editing the object, *much* easier than editing 300+ points.

[nightoftheroundtable]

no one has actually anwsered my question:( can you only subdivide just the objects selected or can you also subdivide the surfaces. if you can please tell me how

[Willy]

I'm not sure, I haven't tried it but I think you can fragment the object then choose some of the surfaces and merge them into a new separate object. Then that object could be subdivided separately from the rest. Then I suppose you could fragment everything again and merge the whole thing back into one object. Or maybe it would be better to keep the separate objects. I guess it depends on what you are wanting to do.

[coanda]

I'm not too hot on this whole sub-divide business, so a quick question........can sub-divide help to model real objects (say, an aircraft) accurately, from base polylines/splines? or is it just make made-up stuff look good??!! :)

[Spinner]

coanda
One application of subdivide can round off a low poly model made to accurate dimensions.
For non-fiction aircraft, its a trade off between poly budget and appearence like all modelling. So its more usefull if your end target is a picture of the aircraft, than if its a model for in game use.
IMO Its one more string in your bow and all AC3D users should familiarise themselves with it, but that applies to all AC3D commands. Each one gives you more possabilities.

[Willy]

Been working on a Trek style control panel. Can't figure out a way to make the cut-outs in the top for the recessed panels with all the okudagrams and etc.

http://www.citlink.net/~ckearley/Panel03a.jpg

.

[Willy]

I figured one way to give objects a nice rounded edge with subdivision without totally changing the shape of the entire object. It involves extruding two or more surfaces so that when you subdivide the object it rounds the edges instead of changing the over-all shape of the object so much. Here's an example pic:

http://www.citlink.net/~ckearley/Panel06a.jpg

Then I set Crease Angle to 180, subdivide twice then Smooth and I get this:

http://www.citlink.net/~ckearley/Panel06b.jpg

There seems to be a little bit of a bug in the Extrude function though, sometimes the vertices drift off axis while the surface is being moved and they have to be corrected manually.

.