[x3d-public] Light intensity now unbounded in X3D4, fixed schema/X3DUOM and renamed intensityType as unitIntervalType

[John Carlson]

Does fixed in mean ready to test?  I've barely gotten the new schema
working, broke in Java, Python, ant, etc. etc.  So far Ajv seems to be
working again.  Lots of new revs of software.

There should be a cleaner Java validator out of this, I hope.

John

On Sun, Jan 16, 2022 at 10:52 AM Brutzman, Donald (Don) (CIV) <
brutzman at nps.edu> wrote:

> Historically in X3D3 light intensity values have been bounded [0,1]
> inclusive.  While performing regression testing found an unhandled example
> of <DirectionalLight global='true' intensity='3'/> derived from a glTF
> model conversion.
>
>
>
>    - GlamVelvetSofa.x3d which was converted by view3dscene from glTF
>    example:
>    -
>    https://github.com/KhronosGroup/glTF-Sample-Models/blob/master/2.0/GlamVelvetSofa/glTF/GlamVelvetSofa.gltf
>    -
>    https://X3dGraphics.com/examples/X3dForAdvancedModeling/GltfSampleModels/GlamVelvetSofa.x3d
>    -
>    https://X3dGraphics.com/examples/X3dForAdvancedModeling/GltfSampleModels/GlamVelvetSofaIndex.html
>
>
>
> As part of X3D4 Architecture, all light intensity values are now allowed
> to have any non-negative value.
>
>
>
>
>
>    - X3D 4, Lighting component, 17.3.1 X3DLightNode
>    -
>    https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/lighting.html#X3DLightNode
>
> *17.3.1 X3DLightNode*
>
> X3DLightNode : X3DChildNode {
>
>   SFFloat [in,out] ambientIntensity 0     [0,1]
>
>   SFColor [in,out] color            1 1 1 [0,1]
>
>   SFBool  [in,out] global           FALSE
>
>   SFFloat [in,out] intensity        1     [0,∞)
>
>   SFNode  [in,out] metadata         NULL  [X3DMetadataObject]
>
>   SFBool  [in,out] on               TRUE
>
>   SFBool  [in,out] shadows          FALSE
>
>   SFFloat [in,out] shadowIntensity  1     [0,1]
>
> }
>
>
>
> Also
>
>    - 17.2.1 Light source semantics, 17.2.1.1 Overview
>    -
>    https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/lighting.html#LightSourceSemantics
>
> Any node used as a source of illumination is derived from *X3DLightNode
> <https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/lighting.html#X3DLightNode>*.
> All light sources contain an *intensity*, a *color*, and an
> *ambientIntensity* field. The *intensity* field specifies the brightness
> of the direct emission from the light, and the *ambientIntensity* specifies
> the intensity of the ambient emission from the light. Light intensity may
> range from 0.0 (no light emission) to infinity. The *color* field
> specifies the spectral colour properties of both the direct and ambient
> light emission as an RGB value. The on field specifies whether the light is
> enabled or disabled. If the value is FALSE, the light is disabled and
> will not affect any nodes in the scene. If the value is TRUE, the light
> will affect other nodes according to the 17.2.1.2 Scoping of lights
> <https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/lighting.html#ScopingOfLights>
> .
>
> Typically lighting *intensity* values are within range [0,1] for
> consistent composability of multiple scenes with independent lights.
>
>
>
>
>
> 1.  Dick, I think we need to check the above wording to avoid ambiguity
> since ambientIntensity and shadowIntensity remain in range [0,1]
>
>
>
> 2. Have relaxed upper bounds on lighting intensity in X3D4 schema and
> X3DUOM.
>
>
>
> Since the restriction of [0,1] appears many times, an internal type name
> is used.  As indicated in Schema changelog entry which follows, am renaming
> it for clarity and correctness. This has no effect on specification, since
> it is not an official data type, but it does help X3D XML Schema and
> X3DUOM-derived codebases be exactly consistent and correct.
>
>
>
> - rename intensityType as unitIntervalType for correctness
>
>   https://en.wikipedia.org/wiki/Unit_interval
>
> - (v4.0) relax upper bounds on light intervals, previously [0,1] now
> [0,infinity]
>
>   which matches glTF Physically Based Rendering (PBR) parameters
>
>
>
> This change will ripple through various APIs and stylesheets in the next
> few days.  So far, deployed in X3D XML Schema, X3DUOM and X3DJSAIL.
>
>
>
> Confirmation/correction comments and questions are always welcome.  Once
> again thanks to Michalis Kamburelis for his rigorous design alignment of
> X3D with glTF.
>
>
>
> Have intense fun with X3D!  8)
>
>
>
> 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 https://
> faculty.nps.edu/brutzman
>
>
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