Update reference card for 3D Tiles 1.1

[javagl]

One point of https://github.com/CesiumGS/3d-tiles/issues/651 that had still been on my plate (and been waiting there for too long) is the update of the reference card for 3D Tiles 1.1. To avoid filling the repo with commits of SVG (or even worse, binaries like PDFs), certain points can probably be sorted out here.

I assume that the result should be a dedicated reference card for the new features of 3D Tiles 1.1. Specifically, I assume that it should not combine the reference card of 1.0 and the reference card for 'Next'. Instead, it should rather be an update of the former 'Next' reference card.

Two broader, structural questions:

• Where/how to present the S2 extension? It could be a dedicated section at the end, to make clear that it is not part of "3D Tiles (core) 1.1". Or it might be omitted in the reference card altogether: It only was a short section to present the extension, but in terms of contents, it was not adding much value beyond the main S2 README.

• Where/how to present the glTF extensions? There already is some confusion, and people think that the glTF extensions are somehow "part of" Next/1.1. Also, the glTF extensions have been split into mesh_features and structural_metadata in the meantime. One could mention structural_metadata as one implementations of the 3D Metadata Specification. But this should be done carefully, with a disclaimer: Technically, this extension is not part of 3D Tiles. For now, I think that it could make sense to omit the page "The EXT_mesh_features Extension" from the 'Next' reference card. This could be moved into a short (1-2 pages) but dedicated overview of the proposed mesh_features and structural_metadata extensions.

[lilleyse]

I assume that the result should be a dedicated reference card for the new features of 3D Tiles 1.1. Specifically, I assume that it should not combine the reference card of 1.0 and the reference card for 'Next'. Instead, it should rather be an update of the former 'Next' reference card.

So it would be like a "what's new in 3D Tiles 1.1?" reference card? Even though I wasn't thinking that originally that's probably the right thing to do.

Where/how to present the S2 extension?

It would be fine to omit

Where/how to present the glTF extensions?

There could be a separate resource that describes all the recommended glTF extensions. Which is reminiscent of the glTF geospatial profile: https://github.com/KhronosGroup/glTF/issues/2092

[javagl]

Right now, we have the /reference-card subdirectory and the /next/reference-card subdirectory. The latter is supposed to be removed at some point. The updated reference card will contain what's new for 3D Tiles 1.1.

Two options come to my mind:

• There could be a /reference-cards directory, with 1.0 and 1.1 as subdirectories
• There could be a /reference-card-1.1 directory

Also: I'd do this update in a state that is branched off from draft-1.1. (It could be done in master, because it's largely independent of other changes, but think that doing it in the draft-1.1 branch just makes more sense)

Here's the 'release candidate':

3d-tiles-reference-card-1.1-2022-07-25-RC01.pdf

[lilleyse]

There could be a /reference-cards directory, with 1.0 and 1.1 as subdirectories

This option seems good. Have you thought about where the PDFs would go and how the README's would be updated?

I'd do this update in a state that is branched off from draft-1.1

:+1:

[javagl]

Have you thought about where the PDFs would go and how the README's would be updated?

The current reference card PDF is in the root directory. I considered to move it to the reference-cards directory, but thought that there might be some direct links to this file out there. So I just added the 1.1 PDF in the root directory as well.

The main README.md now links to the reference-cards subdirectory, and the reference-cards/README.md contains the preview images now. (They could both be added to the main README, but maybe it's better to keep the main README lean...)

Entry point from main README: https://github.com/javagl/3d-tiles/tree/draft-1.1-reference-card-update#3d-tiles-reference-cards

The PR is at https://github.com/CesiumGS/3d-tiles/pull/706

(This PR does NOT yet remove the next subfolder, although we might be approaching the point where this could be done)

[lilleyse]

Added in https://github.com/CesiumGS/3d-tiles/pull/706

[lilleyse]

(This PR does NOT yet remove the next subfolder, although we might be approaching the point where this could be done)

Yeah, I think we can start that process now by removing next from the draft-1.1 branch. The revision history and logos have served their purpose and are ok to remove (and will still be accessible in the git history if we need them). The rest of the content has migrated to the new resources page and reference card. I don't think there's anything left that needs to be kept.

Once draft-1.1 is ready to merge into main we'll need to update any broken links that point to next.