[x3d-public] [x3d] Spec Comment by on 19774-1: H-Anim Architecture - V1.0

Sat May 19 06:52:02 PDT 2018

Forwarded to HAnim Working Group for consideration.  Thanks for your review and these comments.

On 5/17/2018 10:00 PM, Spec Feedback wrote:
> -- Submitter indicates that this comment may be public: *Yes* --
> 
> Comment on 19774-1: H-Anim Architecture - V1.0
> All sections
> 
> 
> -----------------
> These comments were collected from the entire specification document. They
> are divided into 2 sections - General and Specific.  Each numbered item is a
> separate comment.
> 
> 
> General Comments
> 
> 1: The fonts for the fixed-width text elements appear to be significantly
> smaller than that surroiuding text. For eample see 4.2.3
> 2: The text appears to be responsive (viewable in a variety of browser
> widths); however, this was not confirmed using multiple devices. The images
> are not responsive, either by rearranging multiple images across the page or
> reducing the size of the image. This may not be a desired feature of the
> document, but should be mentioned.
> 3: This document does not define industry-standard practice, but either
> defines a separate means or a more general means of h-anim design. This
> extends from concepts (individual components vs. single mesh skin) to
> terminology. (For example, rigging is defined in section 3, but never used in
> section 4.) As a result the document is not easy to read or comprehed for
> someone use to industry-style humanoid anmiation.
>     a: For reference, industry-style process requires a single-mesh skin that
> is then rigged (skeleton creation with skin weighted-attachment to bones).
> “Bones” are used more frequently than “joints”, but both terms are
> understood.
>     b: For rendering purposes, skin vertices are generally restricted to being
> weighted to no more than 4 joints. This is not a hard requirement, but based
> on practicality and performance, especially real-time performance.
> 4: For a document that is labeld “Humanoid Animation”, there is very
> little (and perhaps no) discussion of animatation techniques of how the skin
> is animated based on joint motion. 19774-2 (minimally reviewed) appears to
> relate how to relate motion capture to joint animation of H-Anim characters.
> 
> Specific Comments
> 1: It is not clear from the text in 4.2.3 exactly what is required. The
> paragraph states both of the items below. It is not clear if a skeletal
> structure that meets (b), but uses something else besides a joint object to
> the end effector of each appendage qualifies as a H-Anim compliant figure.
>     a: “The skeletal description of the H-Anim figure consists of a tree of
> Joint objects that define the transformations from the humanoid_root Joint to
> the end effector of each appendage of the humanoid.”
>     b: “The only requirement of this International Standard for the
> definition of the skeletal hierarchy is that it shall have a humanoid_root
> Joint object defined. All of the other Joint objects are optional and are not
> required for a humanoid figure to be H-Anim compliant.
> 2: It is not clear if the LOAs and other skeletal definitions are normative
> or not. There is material in the early part of Section 4 that state or imply
> that they are optional or not even relevant (for non-human like figures);
> then later in the section (especially when skeletalConfiguration is
> “Basic”) that the definitions are required. The text needs to be
> rewritten to make these distinctions clearer.
> 3: Section 4.8.1, 3rd paragraph defines what it means for two skeletons to be
> of the same configuration without defining what “identical” means. Does
> identical mean that all of the transforms are the same? Is a reclining figure
> in the standard pose the same as one arranged on its head? Does scaling
> matter? If the idea is that two skeletons are identical if all transforms
> from the root node are the same, then that should be stated more clearly.
> 4: Section 4.8.4 appears to meet the requirements of 4.8.2 and not 4.8.3. It
> should be a sub-clause of 4.8.2 as it pertains specifically to human-like
> figures. If not moved to a sub-clause, it needs to be made clear in 4.8.2 and
> 4.8.4 that these sections only apply to human-like.
> 5: Section 4.9 also appears to apply specifically to human-like figures.
> There is no obvious statement about the connection and cross-requirements
> with this section.
> 6: Section 4.9.5 (and probably others) refers to facial anomation by
> animation of joints to move facial features. There is no discussion of the
> (not exclusive) industry standard of using morph targets to handle facial
> expression changes and combinations.
> 7: Section 4.9.8 appears to conflict with statements made in section 4.2.3.
> This conflict needs to be removed or clarified that certain restrictions only
> apply to certain kinds of models.
>     a: 4.2.3: “This hierarchy may include any number of optional model
> specific Joint objects, which may be dispersed among the standard H-Anim
> Joint objects. As long as the ancestral ordering of the standard Joint
> objects is preserved, model specific Joint objects may be inserted between
> the standard Joint objects in the hierarchy.”
>     b: 4.9.8: “No new Joint objects are allowed within the chain of the
> standard Joint hierarchy. These non-standard Joint objects may be children of
> either standard Joint objects or other non-standard Joint objects.”
> 8: Section 7.3 specifies the minimum support requirements for VRML/X3D. It is
> not clear why X3D nodes not related to creating (e.g., IFS), positioning
> (e.g., Transform), or texturing (e.g., TextureTransform) models are included;
> especially in light of Section 7.4 that only requires the above three
> capabilities plus a viewing requirement. For example, there is no requirement
> in section 7.4 for lighting, navigation, or general information.
> Suggest fix: Define the general requirements first, then indicate the minimum
> VRML/X3D requirements, and lastly the recommended capabilities.
> 9: Annex F is listed as informative; however, the first sentence of F.2
> indicates that certain things shall be done. Earlier in the document it was
> indicated that the various LOA definitions only applied to human-like
> cahracters. The intent of this section needs to be determine and the text and
> perhaps other places in the document needs to be made consistent.
> 10: The industry-style for creating animated characters is to model the skin
> first, then rig it (create the skeleton and assign skin vertex weights). This
> is not the process described in Annex F. It should be made clear that this is
> different from industry and educatuional practice for US-style animation.
> 
> -----------------
> 
> Submitted on Thursday, 2018,  May 17 - 10:00pm
> by  (Leonard Daly )
> IP: 174.237.6.109
> 
> See: http://www.web3d.org/node/1694/submission/2675
> 
> 
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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