[x3d-public] What is H-Anim?

[Joe D Williams]

----- Original Message ----- 
From: "Leonard Daly" <Leonard.Daly at realism.com>
To: "X3D Public" <x3d-public at web3d.org>
Sent: Thursday, October 13, 2016 10:39 AM
Subject: [x3d-public] What is H-Anim?


> From reading H-Anim in detail (especially Part 1), it appears to me
> that it is primarily doing two things

Where would you get the idea that HAnim does not do deformable skin?

>
> 1) Defining animation with deformable skin
>

I would say it is defining a 'standard' skeleton with a 'standard' 
pose that can use geometry as children of segments or a deformable 
skin that is a child of the humanoid. Either or both segment geometry 
and/or skin geometry can be used. The segment geometry is animated 
when the segments move by animating the rotation of joints in the 
skeleton hierarchy. Skin is animated by weighted displacement of 
individual mesh vertices according to individual or multiple joint 
rotations.

>
> 2) Define bone definition and naming for humanoids.
>

Yes we have standardized names and example 'human' space dimensions 
for Joints, Segments, and Sites
We don't call it a bone, we call the bone a segment.

>
>  I noted that
> humanoids (as defined in the spec 4.2.1) are not required to have 
> the
> normal human-like appendages (1 head, 2 arms, 2 legs)

tha spec humanoid is one of 5 defined LOAs. All LOA choices include 
site locations for all appendages but may not include the complete 
skeketon

> [http://www.web3d.org/documents/specifications/19774-
> 1/V2.0/HAnim/concepts.html#HAnimFiguresOverview]
>

That is just an isolated paragraph about the versatility of the basic 
hierarchal joint model. Besides, your comment is based on a paragraph 
that has had no vetting this round. To study the HAnim, you should 
base it on V1.0 and figure that the CD V2.0 for Part 1 is a bit 
scrambled and incomplete at this point relative to V1.0.

All other information is clear that the target is a humanoid figure 
with a level of articulation that depends upon the number and 
hierarchy of the joints.

>
> If X3D were to included deformable skin animation as an intrinsic 
> part
> of the X3D specification, ...

it already does

>  ... would #1 be required?
>

Not sure what you mean. Animation of a continious mesh deformable skin 
according to joint rotation is one feature of HAnim. Another tool for 
deformable geometry is the DIsplacer node. All big time authoring 
tools do these, although for many the skin animation binding target is 
illustrated as a bone. No difference.
.
>
> If not, that leaves #2. It seems to me that this section is optional
>

Hey, a general concept: To have deformable skin, you use a skeleton. 
If not, then that technology is not avaliable to X3D. Or else you are 
mistaking calling the dragging lumps of 'skin' geometry not connected 
to a skeleton around from keyframe to keyframe as skin animation. That 
is not the 'standard' sort of skin animation we do.

> based on references in the document to "are common", "generally
> categorize", "may have", "model specific". It seems that if one is
> modeling a human (not humanoid), then this structure should be used; 
> but
> if not a human, the the variations are endless.
>

True, the variations are endless, like real life except for life there 
is an end. However, we are aiming at a 'standard' humanoid dimensioned 
in 'human' space having a realistic skelton that can use 'standard' 
animations.

The actual geometry used to produce surface features of the model 
includes any sort of X3D geomentry. For skin we seem to do best with 
an indexed geometry since for deformable skin animation we need to 
know the order of appearance in the user code of each vertex of the 
skin field.

>
> I think the document needs an improved focus
>

True in part. Mostly it needs consolidation of important skeleton 
realtionships and some better examples.

>
> and close work with X3D WG
> to determine if deformable skin animation is to be included in a 
> future
> version of X3D.
>

Too late, the horse is out of the barn. We do it the way everyone does 
it. It already is included. The document is much at fault for you to 
miss that. Look at the skinCoordIndex and skinCoordWeight fields of 
the Joint and their descriptions.

Why not actually look at user code of some examples and actually look 
at some examples of this humanoid really running?
See attached. Please look at the user code also. Runs best in BS 
Contact free.
Sorry, as far as I know X3DOM don't do skin yet.
Please tell me what you think.

I agree with your recommendation that the X3D working group should 
look at the standard, but since deformable skin animation is included 
in V1.0 and demonstrated by multiple X3D browsers, please pick another 
item upon which we should make a detailed determination.

My comment along these lines is that HAnim seems to need at least two 
support levels:
1 is just segment geometry and
2 is add skin geometry.
because implementing 2 seems to be a large step up for some browsers

Thanks,
Joe

Can't wait to see your comments on Part 2.


>
>
> -- 
> *Leonard Daly*
> 3D Systems & Cloud Consultant
> LA ACM SIGGRAPH Chair
> President, Daly Realism - /Creating the Future/
>


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