[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.


"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:




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
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