[x3d-public] x3d minutes 20 May 2022: submission of X3D4 Draft International Standard DIS) document nearing completion; tweeted

[Andreas Plesch]

For convenience, let me point to

https://www.khronos.org/blog/khronos-prepares-gltf-2.0-to-be-submitted-as-an-international-standard

which links to

https://www.khronos.org/registry/glTF/specs/2.0/glTF-2.0.html

as the glTF spec. being standardized.

I could not find light specifications in this document.

As Michalis had pointed out (a few times) glTF is not concerned at all
with light sources including environmental or image based lights.

There are extensions to the glTF format which add light sources but
these extensions are optional and not part of the Khronos standard
submission. The extensions exist because the PBR material model which
glTF uses works best with environment lights (and I think presupposes
such a fully defined hemisphere/environment for a physically
reasonable total energy budget of input and output of light, eg. no
arbitrary 'ambient' light contributions). But the PBR equations can be
used with any light.

So if glTF standard compatibility is the main concern, there is no
need to include an EnvironmentLight node in the spec. in my view.

That does not mean it would not be beneficial to add such a light node
to X3D once it is ready. That will help with de-facto glTF
compatibility since most glTF viewers support these non-standard
extensions.

Cheers, Andreas


> Date: Mon, 23 May 2022 16:42:01 +0000
> From: "Brutzman, Donald (Don) (CIV)" <brutzman at nps.edu>
> To: "X3D Public Mailing List (x3d-public at web3d.org)"
>         <x3d-public at web3d.org>
> Subject: Re: [x3d-public] x3d minutes 20 May 2022: submission of X3D4
>         Draft International Standard DIS) document nearing completion; tweeted

...

> a.      Mantis 1336, X3D4 Lighting component, 17.4.2 EnvironmentLight -
> Khronos glTF extension for image based lighting
>
> https://www.web3d.org/member-only/mantis/view.php?id=1336
>
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/
> components/lighting.html#EnvironmentLight
>
>
>
> Michalis or Dick, can you please confirm whether or not this is part of glTF
> 2.0 PAS submission to ISO.  If so we will include it, otherwise it is
> deferred to X3D4.1.
>