Organic Modelling Part.II -- Subdivision Surfaces Features

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philovivero
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Organic Modelling Part.II -- Subdivision Surfaces Features

Post by philovivero »

I had made a post earlier here:

Metaball modelling Thread

I've decided to go ahead and try using Subdivision Surfaces to do my modelling. I've read up on edge loops and tris vs. quads etc. and have come to the conclusion that Blender really needs a few more features to make this a tractable problem. I'm sure all these features have been requested already, so really count this as a verbose "me too!"

(1) When adding new vertexes to the control mesh, the vertexes should be placed in an attempt to maintain the subdivision surface shape. Look at these four screenshots where I use the knife tool to create midpoint-divided polys on the back of her head:

Image
Image
Image
Image

Yikes! This makes trying to model at a rough level, then adding detail where appropriate nearly impossible. The mesh becomes completely unrecognisable. This has to be the #1 most important feature request.


(2) Symmetry! I can't count the number of times in doing the above-illustrated model that I've wanted to have symmetry. There needs to be N-degree symmetry for at least N=2. Higher-order symmetry for models like octupi and other such creatures might be useful.


(3) Welding. If I have two meshes with open ends with X vertexes on both open ends, could I please select the vertexes and "weld" them together? The algorithm can be stupid: weld each vertex from MeshA that is closest to the vertex in MeshB and fail if there is ambiguity. Welding each vertex one at a time is tedious.



(4) Tris --> Quads (Symmetry! Please!) Create a Tri-based set of edge loops. Use Alt-J to convert to quads. The way it converts the tris on the left is different than how it converts the tris on the right, and symmetry is destroyed. It'd also be nice if it would keep doing conversion until all tris become quads. It looks like the current algorithm is very concerned with only converting existing tris into quads and not changing the shape of existing quads. I understand this hesitation, but can I have a "seriously, convert *ALL* tris to quads, even if you must create entirely new vertexes and change my mesh shape some" override option? It's quite a chore to convert tris to quads many times.

--
philovivero

slikdigit
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Post by slikdigit »

this thread really should start in elysiun, since some of the features you're asking for exist, and then keep just feature stuff to blender.org.
1-all subdivision modellers that I've used are the same- however, there are some comments I'd like to make: the ctrl-r tool for adding edgeloops has some proportional features that help maintain shape. also, smoothing the added verts can sometimes help. note- usually, when adding verts (there are exceptions) I'm trying to change the shape, not keep it the same, so it isn't an issue.
2- symmetry exists, in the form of linked copies. Consult the manual or ask on elysiun on how this is done- quick example: bilateral symetry is (object mode, starting from one half the model) alt-d then s then x then 1 then - then enter (none of these keys on the numpad)
3- welding exists, check your toolbox when in edit mode, you can either weld verts at center or cursor, or select a bunch of verts and rem doubles the ones that are close based on distance.
4-see 2. edit mesh really doesn't have a concept of symetry internally, just a mesh data structure. you can always select all the tris you have and convert to tris. sometimes, blender doesn't do this the way you want , so you can select less and iterate. using edge tools helps a lot since you don't generate that many tris to begin with.

theeth
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Post by theeth »

slikdigit wrote:2- symmetry exists, in the form of linked copies. Consult the manual or ask on elysiun on how this is done- quick example: bilateral symetry is (object mode, starting from one half the model) alt-d then s then x then 1 then - then enter (none of these keys on the numpad)
Use the mirror tool (Ctrl-M) instead of the scaling trick. Be aware that it's pivot mode sensitive (best to use with cursor mode in edit mode or center mode in object mode).

Martin
Life is what happens to you when you're busy making other plans.
- John Lennon

slikdigit
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Post by slikdigit »

old habits die hard :wink:

theeth
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Post by theeth »

slikdigit wrote:old habits die hard :wink:
At least you didn't say S - X ;)
Life is what happens to you when you're busy making other plans.
- John Lennon

sten
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Post by sten »

theeth wrote:
slikdigit wrote:2- symmetry exists, in the form of linked copies. Consult the manual or ask on elysiun on how this is done- quick example: bilateral symetry is (object mode, starting from one half the model) alt-d then s then x then 1 then - then enter (none of these keys on the numpad)
Use the mirror tool (Ctrl-M) instead of the scaling trick. Be aware that it's pivot mode sensitive (best to use with cursor mode in edit mode or center mode in object mode).

Martin
but mirroring alt+d copied meshes haven't worked for me what I can recall, both meshes wants to be mirrored...and when working on symetric models that is not what you want,therefore I use ctrl+m outside editmode(in objectmode) - or maybe I am doing something wrong? and it is not fun when pivot/axis faces wrong and trying to do this ctrl+m mirror tool, I know I tried, took some time until I got it, lol :)

theeth
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Post by theeth »

ztonzy: of course, if you use it in edit mode, it mirrors both instance ;)

Martin
Life is what happens to you when you're busy making other plans.
- John Lennon

sten
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Post by sten »

hehe,

@theeth:

I just found out how to do it ;) not easy, kind of wacky mirror feature scaling in reverse in one axis... :P

add cube --> move cursor to place it at side of cube --> shift+s/cursor to grid --> alt+d on cube --> set pivot to follow cursor --> S-key to scale --> minus-key --> 1-key --> enter... voilá !!

heh...that's how I got it to work ;) :P

theeth
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Post by theeth »

You don't have to do that, that's just what I was explaining to slikdigit. All you have to do is use the mirror tool (Ctrl-M) in object mode.

Martin
Life is what happens to you when you're busy making other plans.
- John Lennon

sten
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Post by sten »

theeth wrote:You don't have to do that, that's just what I was explaining to slikdigit. All you have to do is use the mirror tool (Ctrl-M) in object mode.

Martin
yes I know, but that's axis pendant...isn't it ? (ctrl+m)

theeth
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Post by theeth »

Scaling is also axis dependant. It's the same code :P

The method you suggested is only good for a cube since it flips on all axis. Try it with an irregular mesh, you'll see.

Martin
Life is what happens to you when you're busy making other plans.
- John Lennon

sten
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Post by sten »

hehe, okey...

:lol:

philovivero
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Thank you for replies!

Post by philovivero »

I thank you all for your replies. Especially slikdigit! My lack of knowledge about symmetry was so sad, and I wasted so much time. But now I've known about it a week or so, and here's the result!

Image

I've put in a basic armature now as well, and begun posing the model. Still these two features would be lifesavers:

1. Merge sets of vertexes. No, the current merge won't work. If I have to select pairs of vertexes and merge them, it'd take HOURS. There are hundreds of very tiny, very intricate vertexes on that model. If I can't merge the two halves of the model, there is a nasty seam that causes all sorts of deformation problems. Get the .blend at the end of this post, get into pose mode, and pose her. Watch in horror as her face splits into two chunks. BAD BAD BAD!

2. When modifying the mesh (using Knife tool, or face loop cut) try to keep the shape of the underlying mesh. Yes, the point is to change the mesh shape, but the odds are the current mesh is 90% in the correct shape already. See the above example. It's still a legitimate feature request.

Here is the .blend for those who would like to play with it: http://faemalia.net/girl-posed.blend.gz.

z3r0_d
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Re: Thank you for replies!

Post by z3r0_d »

philovivero wrote:1. Merge sets of vertexes. No, the current merge won't work. If I have to select pairs of vertexes and merge them, it'd take HOURS. There are hundreds of very tiny, very intricate vertexes on that model. If I can't merge the two halves of the model, there is a nasty seam that causes all sorts of deformation problems. Get the .blend at the end of this post, get into pose mode, and pose her. Watch in horror as her face splits into two chunks. BAD BAD BAD!
what you're supposed to do [and have been able to do since before merge verts] is use the remove doubles function

if your verts don't all lie on that center line, then you need to put them there

put the 3d cursor on that center line somewhere [I usually shift+s cursor to grid after left clicking near where I want it to be, but this might not apply to you]

make scaling take place around the 3d cursor (period key)

select the verts that should be along the center line

scale, and constrain to perpendicular to that plane, and hold control and scale down to zero [it is easier than perhaps it sounds. with the mouse on say the right middle of the screen, press the S key, move towards the center of the screen somewhat, press the middle mouse button, then hold control and move all the way to the center of the screen [watch the text on the header to reach 0]]

then do remove doubles

slikdigit
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Post by slikdigit »

that's a really beautiful result. nice work

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