[x3d-public] X3D working group meeting minutes16 NOV 2018

Andreas Plesch andreasplesch at gmail.com
Tue Nov 20 06:03:34 PST 2018


Added note to glTF lights below:

On Tue, Nov 20, 2018 at 1:23 AM Andreas Plesch <andreasplesch at gmail.com>
wrote:

> ad point clouds:
>
> massive, lighted point clouds should be possible to implement in
> x3dom/x_ITE as webgl shaders exist. But still significant investment in
> resources/time.
>
> ad glTF inline:
>
> EXPORT/IMPORT: I would favor default exporting/importing of all glTF nodes
> as equivalent X3D nodes using their glTF names or index as DEF names,
> probably under an inline provided namespace name as prefix.
>
> Scenes: a glTF without a scene but just a collection of nodes is valid.
> Since the scene graph is then incomplete, it is required not to be
> rendered. It can be used as a library of resources to be included somewhere
> else in the X3D. This way a by default imported glTF which only contains a
> material can be used in a Shape node's material field. Referencing a
> geometry is trickier since in glTF geometries do not have a name or an
> index. They are part of a mesh (Shape in X3D). So 'mesh_1' could refer to
> the complete mesh as a Shape, and 'meshgeometry_1' or just 'geometry_1' to
> just the geometry of mesh_1.
> A single glTF can contain multiple scenes although I have not seen one.
> X3D could just bail and say undefined, or always render the first one only.
>
> Cameras: almost 1:1 mappable to Viewpoint, except for near/far which
> correspond to NavigationInfo fields. As such added to Viewpoint list and
> stack.
>
> Animations: can be mapped to TimeSensor/Interpolator/Route combos. But
> glTF does not define when an animation begins playing. It is expected that
> after import the player/app decides that. Most glTF viewer just start
> playing all animations after loading. Control in X3D would be via imported
> TimeSensor.
>
> cubicspline: as mode of interpolator.
>
> Lights: glTF itself does not define lights. A proposed material commons
> extension defines lights but is in limbo.
>

There is now another extension:
https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
. It defines point, directional and spot lights, largely compatible with
X3D lights but has a different recommended attenuation law, and required
non-rendering/culling beyond the max. distance. The extension is supported
by the glTF blender exporter. There is no ambient light.


>
> PBR material: cannot be mimicked by Blinn-Phong shading and requires a
> different set of parameters. In effect, a new PBRMaterial X3D node is
> needed. Equations for an example shader are provided, but not normative.
> While not included in glTF, image based lighting (IBL) is often used in
> glTF viewers. An EnvironmentLight X3D node was proposed.
>
> That became longer than expected. Thanks for reading,
>
> Andreas
> ---
>
>>
>> Message: 2
>> Date: Fri, 16 Nov 2018 18:06:11 +0000
>> From: "Brutzman, Donald (Don) (CIV)" <brutzman at nps.edu>
>> To: X3D Graphics public mailing list <x3d-public at web3d.org>
>> Subject: [x3d-public] X3D working group meeting minutes16 NOV 2018:
>>         X3D Semantic Web, X3Dv4
>> Message-ID: <d5aaf236-0290-f122-cb15-1dbcc0954f69 at nps.edu>
>> Content-Type: text/plain; charset="utf-8"
>>
>> 0. Attendees: Anita Havele, Michalis Kamburelis, Vince Marchetti,
>> Christophe Mouton, Nicholas Polys, Dick Puk and Don Brutzman.
>> ==============================
>> 3. Primary working group goal is X3D version 4.0.
>>
>>         X3D Version 4.0 Development
>>         http://www.web3d.org/wiki/index.php/X3D_version_4.0_Development
>>
>> New.  Can we propose certain parts of X3Dv4 as recommended for
>> implementation testing by the end of the year?  Our motivation is encourage
>> accelerated development of the most important capabilities and get them
>> widely available for testing and demonstration.  Intended target
>> implementations are X3DOM, X_ITE, Castle Game Engine and perhaps others.
>>
>> Candidates:
>>
>> a. *3D Printing and Scanning Profile*.  Addition of Point size, Point
>> normals, possibly point sprites.  Leonard correctly notes that we need to
>> look ASTM E57 mappability/portability as well. Anything else?
>>
>>         Wikipedia E57: A file format developed by ASTM International for
>> storing point clouds and images.
>>
>>         ASTM Committee E57 on 3D Imaging Systems
>>         https://www.astm.org/COMMITTEE/E57.htm
>>
>>         Wikipedia: Point cloud
>>         https://en.wikipedia.org/wiki/Point_cloud
>>
>> b. *Inline support for glTF and Physically Based Rendering*.
>> -  Michalis notes that required, well-defined glTF lighting model implies
>> experimental X3D lighting-model changes that correspond to).
>> - Vince described how we need to scope this to Shape/mesh capabilities,
>> or possibly other glTF capabilities also e.g. Camera etc.
>>
>> c. Others?  *RenderedTexture* might be easy.
>>
>>         http://www.xj3d.org/extensions/render_texture.html
>>
>>         TODO: Michalis will post further information
>>
>> For CAD Design Printing Scanning group's arena, there is a lot of work
>> going on with STEP.  It would be good to consider our best strategies for
>> STEP support in 2019: encourage translators/import/export?  Best
>> practices?  Native support in X3D?
>>
>> This is a year-end opportunity to prioritize the most feasible and
>> valuable next steps for progress.  We would publish and prioritize a "short
>> list" of what nodes need to be implemented next.
>>
>> Great discussion today!  Nicholas and Michalis each have blogs in
>> preparation for release Real Soon Now (RSN).
>>
>> We intend to proceed in this direction.  I will need help to get this
>> properly proposed publicly by year's end.  Who is willing to lead each
>> category?
>>
>>
>> ------------------------------
>>
>> End of x3d-public Digest, Vol 116, Issue 20
>> *******************************************
>>
>

-- 
Andreas Plesch
Waltham, MA 02453
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://web3d.org/pipermail/x3d-public_web3d.org/attachments/20181120/f4fcda9e/attachment-0001.html>


More information about the x3d-public mailing list