nested models are dangerous : avoid it

[janimatic]

hello everyone

In xsi 6.5 we noticed that nested models corrupt the render scenes.
I tend to avoid nested models anyway but some people here weren't aware of the problem and i wanted to report it since nested models are supposed to be a new feature.
Anyway the full path doesn't reflect the whole hierarchy of nested models so I think nested models isn't something to use at all, except for conveniently transfert a set of models and immediately copy paste models in the scene root after import, but this might also break some mixer/ delta links ...

best regards
Julien

[EdHarriss]

I second the "nested models are bad" concept.
I've had problems before too. Don't do it.

If arranging your scene/housekeeping is your reason for nesting models. There are plenty of good ways to arrange your scene without resorting to nested models. Try using nulls instead and putting those under the model. (This is not always going to work as you'll need models to do certain things, but most of the time it's a perfect workaround.)

[Adrian Lazar]

nested models meaning putting a model in an other model?

[franky]

hm, i just use the setup helge described on xsiblog. using a model with a meshmodel and rig model inside.

so its looks like this

Character Model
.......|
.......-----------01_Mesh Model
.......-----------02_Rig Model

then i export the character model and reference it into the animation scene.

i have some trouble, which i cant really identify the source. could be my rig, could be something else.
i play back the animation and it looks fine. then i load it up the next day and i have a control, that is suddenly offset, and some where else. like the head rotates in mid animation further then it should and from then on it stays screwed. or a foot control is suddenly places 2 units further then it was originally.

Julien, when do you say corrupt.. what does it do really?

[janimatic]

hey Franky,
i mean, the scene crashes on load... I suspect the list of partition members and other scene level groups reconnection with delta is going in an infinite loop or something like that...
Nested models could be an handy way to transfert models across scenes, but it would be easy to provide a safe alternative expending the hierarchy on import...

best regards

[thiago]

nested models = don't do it (unless extremely necessary)

- 1 because it's not reliable.

- 2 because it's bad to have many animation mixers.

- 3 refmodel -> nested model -> crash
Deltas are very dependent on the model structure. Each model will have it own delta... A model inside another is run to death with mixers and general refmodel management.
Offsets, problem with constraints will show up in the next refresh.

BUT refmodels are a special case, sometimes you need it. So you should use it for static, non-specially-rigged objects... Limit yourself.

Sometimes its better to have just one model and get the last geometry version and use gator to transfer the model. Put all with the same name/properties and your delta will understand everything.

[franky]

BUT refmodels are a special case, sometimes you need it. So you should use it for static, non-specially-rigged objects... Limit yourself.


hm, i use ref models since v4 very successfully. several productions that i could not have handled without them.
this time its the first time i use them nested. one level deep.
a master ref model that holds the mesh and the rig ref model in itself.

works fine so far beside the problems i described, which might relate to the rig, not the ref models....
either way, i will revert back to one ref model holding the whole character.

i have good experience with ref models and constraints linking into them as well. the magic works when you load the ref model first and then the model that links into it.

[thiago]

hm, i use ref models since v4 very successfully. several productions that i could not have handled without them.
this time its the first time i use them nested. one level deep.
a master ref model that holds the mesh and the rig ref model in itself.

works fine so far beside the problems i described, which might relate to the rig, not the ref models....
either way, i will revert back to one ref model holding the whole character.

i have good experience with ref models and constraints linking into them as well. the magic works when you load the ref model first and then the model that links into it.

I meant, "refmodels..." - with nested models - "...are a special case sometimes you need it"

Theres already reported problems with nested refmodels and the new delta referencing... we are possibly going to see some improvements on this for the next release of XSI... I hope at least :)



EDIT:
from the known problems list:
• UDEV00238083 - RefModel: Constraint loses animation in Mixer
• UDEV00238644 - Explorer Refresh problem while switching ref model active resolution

This if you are on 6.5... if you are on 6.02 god bless you with refmodels

[franky]

6.5 .. and i reported a whole bunch of them back then on 6.0 ;)
the list shrinked a lot and lets see what v7 got for us.

[scaron]

@janimatic

you log your bug yet?

[janimatic]

hey steven,

i will send a report with a sample scene to support when the production will be over (i am too busy this week...).

[scaron]

hmmm

give me the steps i will repro and log it

[thiago]

do you have lots of refmodels to manage? like export/import/update?
if yes I can send you some scripts I did that help on massive export multiple import/update

Also a little trick: if you drag the .emdl file from the browser and hold Ctrl, it comes as a refmodel ;)