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View Full Version : Other Softwares: grouping and parenting, MAYA vs LW



jeric_synergy
09-08-2013, 12:09 PM
I'm working up on MAYA currently, and something about their Grouping nagged me:

AFAICT, 'Grouping' in Maya is exactly equivalent to Parenting in LW. Okay.

But, this seems silly to me: I would like a Group (which TMK LW doesn't have) that is not related to Motion, which of cource Parenting is.

1) Is this conflation of the two common in software? I remember stumbling over SI's 'parenting' at the time (decades ago) and being confused because it was NOT the same as LW parenting, it was more like a generalized grouping.

2) I think Groups, like we see a little bit of in Soft-Efx et al, could be used more in LW to good effect. For one thing, they could be used as 'render groups'.

geo_n
09-08-2013, 12:24 PM
http://www.youtube.com/watch?v=OFMlHOPjyWA

How can a group not be related to motion. I think you mean selection groups.

Dexter2999
09-08-2013, 12:28 PM
Words can be ambiguous.

Groups=families=Parenting/parented
and/or
Groups=sets

One can intimate heirachy in the relationship while one doesn't.

geo_n
09-08-2013, 12:32 PM
Yeah I meant selection sets. Selection sets, layers usually dont involve motion.

Dexter2999
09-08-2013, 12:35 PM
Oh, I understood what you meant. I was trying to say that when you move to different software they may use a word you are familiar with in a way you aren't used to using it.

geo_n
09-08-2013, 12:39 PM
Yep just wanted to clariffy to the OP since he might get even more confused with selection groups.
Selection sets.... 4am need to keep awake... :D

jeric_synergy
09-08-2013, 12:48 PM
How can a group not be related to motion. I think you mean selection groups.
The MAYA dox just call them 'groups', not 'selection groups'. Each s/w can have their own little terminology quirks. I'm just following their verbiage.

re Dexter2999, There could even be hierarchy in groups (ie "nested selection sets") that still didn't involve motion. Logical grouping and motion inheritance are two different things, after all. --That would be a neat feature, but I've never seen "nested selection sets".

EDIT: seems like I might, real soon now.... ;)

Surrealist.
09-08-2013, 01:37 PM
In Maya I mostly hear them referred to as Transform Groups. And it is probably better to think of them that way. This has a lot to do with how Maya works at the node level and also how it automatically groups objects and nodes. Some of them can be moved and others can not. For instance when you create a subdivision surface, it automatically makes a duplicate of the object and subdivides it. Both are contained now in a transform group. You edit the low poly version and since it is also linked via nodes to the subdivided one you are updating it as well. This is also important when working with nCloth for example which does a similar thing. There is an input mesh and the cloth (output) mesh. These are linked and grouped. So this is a very specific thing that goes beyond just parenting. They are groups of objects and nodes which generally need to be transformed together.

So for this reason, Inputs and Outputs are also important to gasp I have found. You can always go in to the node editor and connect and disconnect these links as well as delete nodes and so on. But all of that happens basically under the surface so the artist is not required to deal with it unless he/she needs to. But the little arrows are available in the various panels for instance that let you navigate to and from a properties' inputs and outputs. For instance when surfacing and texturing an object you can follow the arrows to the links you have set up at the node level under the hood by linking things like images to a surface in the panel. Of course you can open the node editor and see all of your connections and even work that way if you prefer.

This is something that LightWave could benefit from. Basically making a surface panel like we have but it connects all of the nodes. So you would work basically the same way as with layers but when you are making selections you are also setting up your nodes automatically. This is how Blender works when you use Cycles. Then going into the node editor can be reserved for advanced needs rather than the every day stuff like connecting an image node etc.

Grouping in the generic sense as in an organization of items is done with sets.

The default Outliner has two sets you can not delete:

116925

But you can make more sets and partitions for various purposes:


A set is a collection of objects or components. Any item you can select can be in a set. The set exists as a separate object representing the collection. Unlike groups, sets do not alter the hierarchy of the scene.

In some instances, Maya creates sets for you as you work with objects. For example, when you add a cluster deformer to some CVs of a NURBS surface, Maya makes a set for the CVs. You can edit the set to control the effect of the deformation. Maya also creates sets that represent shading groups and layers, and points controlled by deformers, flexors, and skin.

You can create a custom set so you can work on its items with a single action. For example, you can create a set of NURBS objects, then hide or display the set as a single entity.

You can control the membership of sets easily using the Relationship Editor.


A partition is a collection of related sets. Partitions prevent the sets in them from having any overlapping members. Maya uses partitions to keep sets separate where overlapping members could cause problems.

Maya creates partitions to keep character sets, shading groups, skin point sets, and exclusive deformers from having overlapping members.

You can create your own partitions when you want to create sets that have no overlap.

For example, suppose you’re animating a cartoon character’s nose as he smiles and laughs. You added a cluster to several CVs for adjusting the nose as he smiles and another cluster to different CVs for adjusting the nose as he laughs.

Creating the two clusters creates a set for each group of CVs. Occasionally you want to move CVs from one set to the other. When you move the CVs from one set to the other set, they remain in the first set. You might not want the CVs in the first set because they add undesirable deformations as you transform the cluster.

To avoid this problem, you can create a partition and put both sets in it. The partition prevents one set from having members of another set. When you move the CVs from the first set to the second set, they’re automatically removed from the first set.

If you want to also group objects by layers you can do that as well:

116926

They are grouped under Visibility Render and Animation layers.

I am not a Maya expert by any means. But this is my level of understanding up to this point and I hope it helps.

jasonwestmas
09-08-2013, 01:48 PM
Groups in maya are directly related to transforms. (Selection Sets in Maya are totally different) Maya Groups permit you to apply a single transform (Based on a pivot point) to multiple objects that may all have different pivots and separate transforms. So it's a tree of different transforms. Parenting is related to a Maya Group but it doesn't have to be. In other words we can create parenting hierarchies without groups, but that's rare in a rigging context.

A Maya Layer has no hierarchy, but there are blending modes between the layers. There are three different layer types that I know of. Display, Render and Animation.

tburbage
09-09-2013, 01:14 AM
A Group in Maya is just a transform node with one or more transform objects parented to it. Maya separates transform and "shape" data in its nodal structure, so when e.g. you create a cube, it is really a shape node associated with a transform node. When you parent multiple objects in LW to a null, that's basically the same thing as a Group in Maya.

You can also put multiple nodes (including mesh objects, lights, cameras, etc.) into a Set, and set membership doesn't imply any transform relationship.

As Jason mentioned, display layers are really just a specialized form of set.

Surrealist.
09-09-2013, 02:44 AM
Interesting note is that in Blender a Group is a set.

Also it is important to understand this about transform nodes when working with display Layers. This can cause some issues if you are not careful. For example if you select only object in the viewport you are really only selecting the shape node. So when moving object from layer to layer, you can get in a situation where turning off a layer also turns off objects that are not supposed to be associated with it because you "moved" them, when in fact since they are grouped to the transform node, it is still in the other layer where you left it. So it is always best to do object layering by selecting from the Outliner where you can grab both the transform node and the shape node.

Just an additional related tip.