[X3D-Public] [X3D] H-Anim WG, higher LOA considerations

Don Brutzman brutzman at nps.edu
Wed Nov 13 19:54:30 PST 2013


[cc: Medical & x3d-public for possible anatomical expertise]

We are trying to build a better body and are trying to figure out how to go from the current Level of Articulation (LOA) 0,1,2,3 out to the full anatomically correct human skeleton.

Attached is a diagram leading from our discussion today... further informed by Kwan Hee Yoo's work to model high-definition face, hands and feet as H-Anim additions.

On 11/13/2013 6:28 PM, Don Brutzman wrote:
> a further design enhancement, hoping to capture the questions better...
> 
> composability concern:  can different parts in different humans be combined, perhaps merged at a single common joint?

if HAnimHumanoid node might begin by containing any HanimJoint, not just sacrum, then different body parts might be composable at the shared parent/child HanimJoint.

I've always assumed that the sacrum Joint had to be the root.  It would be tedious (and not very composable) if each body part had to have a full skeleton linking it back to sacrum every time.

We looked in the H-Anim specification and didn't find a specific prohibition against other joints as the root...  could be there though. Joe might know.

	http://www.web3d.org/files/specifications/19774/V1.0/HAnim/ObjectInterfaces.html
	http://www.web3d.org/files/specifications/19774/V1.0/HAnim/ObjectInterfaces.html#Humanoid

"The skeleton field contains the HumanoidRoot Joint object.  The Humanoid object is considered the parent object of the HumanoidRoot Joint object and defines a coordinate space for the HumanoidRoot Joint object.  Thus, the Humanoid object's transformation affects the Joint object hierarchy in the skeleton field.  A hierarchy of Joint objects is defined for each H-Anim humanoid figure within the skeleton field of the Humanoid object and a hierarchical definition of joints is present even when the geometry of the humanoid figure is not defined within the skeleton field."

Also found useful:

	http://www.web3d.org/files/specifications/19774/V1.0/HAnim/concepts.html#SkeletalHierarchy

	http://www.web3d.org/files/specifications/19774/V1.0/HAnim/concepts.html#StructureOfAHumanoid

	http://www.web3d.org/files/specifications/19774/V1.0/HAnim/concepts.html#Hierarchy

which does define the complete hierarchy, including

	HumanoidRoot : sacrum


Back to the diagram, going beyond the current limits of HAnim LOA 0 through 3:

Dick insightfully observed that the dotted lines actually run back to the center in this diagram.

it would be very interesting to take the an LOA3 figure and
- flatten it in 2D
- spread out the node tree radially into respective circles for each LOA, since they are all strict subsets
- note what other other parts are still needed and where they go
- in essence, put sacrum at center of attached diagram and propagate the skeleton graph outward across LOAs

Does anyone know of such a flattened skeleton, treating the joints mathematically as a graph structure?

all the best, Don
-- 
Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman
-------------- next part --------------
A non-text attachment was scrubbed...
Name: HAnimHigherLoa-draft4.png
Type: image/png
Size: 74565 bytes
Desc: not available
URL: <http://web3d.org/pipermail/x3d-public_web3d.org/attachments/20131113/d439bc2d/attachment-0001.png>


More information about the X3D-Public mailing list