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

Brutzman, Donald (Don) (CIV) brutzman at nps.edu
Mon May 23 16:41:23 PDT 2022

Thanks for your analysis Andreas.   We reached the same conclusions.

Environment light is now marked for removal from X3D4
* https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/lighting.html#EnvironmentLight

and will be reviewed, then deferred for reconsideration as part of X3D4.1 during our next editors meeting.
* https://www.web3d.org/member-only/mantis/view.php?id=1336

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

-----Original Message-----
From: x3d-public <x3d-public-bounces at web3d.org> On Behalf Of Andreas Plesch
Sent: Monday, May 23, 2022 3:41 PM
To: X3D Graphics public mailing list <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

For convenience, let me point to


which links to


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/P
> art01/ 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.

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