Adds EXT_geopose_basic_euler extension #5

sanjeetsuhag · 2021-05-05T16:05:45Z

This extension to implements Target 2: Basic Euler, with the Yaw-Pitch-Roll of the OGC GeoPose 1.0 Standard (draft).

TODO

Rename to EXT_geopose_basic_euler
Add use cases to overview
Add diagram with a JSON example
Fix schema
Add snippet of that CesiumJS code as a reference implementation in an appendix
Add how this extension interacts with the glTF scene graph and coordinate system
Add property reference from schema
Define lat/lon bounds in schema
Add Known Implementations section

lilleyse · 2021-05-06T19:27:23Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/schema/gltf.EXT_geopose.schema.json

+        "roll"
+      ]
+    },
+    "extensions": {},


longitude, latitude, height, and ypr should be marked as required

lilleyse · 2021-05-06T19:32:16Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+      "longitude": 46.7,
+      "latitude": 25.067,
+      "height": 691.0,
+      "ypr": {
+        "yaw": 0.0,
+        "pitch": 0.0,
+        "roll": 0.0
+      }


Is there a document on github that describes the GeoPose JSON encoding? Would be good to link to that.

lilleyse · 2021-05-06T19:33:26Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+
+## Coordinate Systems
+
+This extension uses WGS84([EPSG:4979](https://epsg.io/4979)) as the coordinate reference system for specifying the position with longitude and latitude specified in degrees. Height above (or below) the ellipsoid must be specified in meters. The yaw-pitch-roll is provided as a rotation-only transform from a WGS84 referenced local tangent plane East-North-Up coordinate system..


More official link to the EPSG:

Suggested change

This extension uses WGS84([EPSG:4979](https://epsg.io/4979)) as the coordinate reference system for specifying the position with longitude and latitude specified in degrees. Height above (or below) the ellipsoid must be specified in meters. The yaw-pitch-roll is provided as a rotation-only transform from a WGS84 referenced local tangent plane East-North-Up coordinate system..

This extension uses WGS84 ([EPSG:4979](https://epsg.org/crs_4979/WGS-84.html)) as the coordinate reference system for specifying the position with longitude and latitude specified in degrees. Height above (or below) the ellipsoid must be specified in meters. The yaw-pitch-roll is provided as a rotation-only transform from a WGS84 referenced local tangent plane East-North-Up coordinate system..

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

lilleyse · 2021-05-06T20:19:27Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

@@ -0,0 +1,68 @@
+<!-- omit in toc -->
+# EXT_geopose


The extension intuitively makes sense but there should be a sentence about how this extension interacts with the glTF scene graph and coordinate system.

The geopose transform would be applied last after the node hierarchy

+z would be facing east, +x would be facing north, and +y would be facing up. I put together a sandcastle to confirm: Sandcastle

It would be helpful to include a snippet of that CesiumJS code as a reference implementation in an appendix. Also maybe link directly to Transforms.headingPitchRollToFixedFrame.

Not sure where you are going forward on this topic, but at least OGC has a draft spec for a GeoPose encoding standard out there for review - maybe you can chime in and maybe you can look into aligning theese ideas with the current version of the draft spec. https://github.com/opengeospatial/GeoPose

By the way I am happy to get on a call, or maybe even invite you as a guest to an upcomming Standards Working Group meeting where you can provide input on the current draft from your perspective. You can reach me on linked in or twitter https://twitter.com/Jan_Erik_Vinje https://www.linkedin.com/in/janerikvinje/

@janerivi we are deeply interested in aligning efforts. I apologize for the lack of context in the pull request. @LisaBosCesium will be in touch.

pjcozzi

@sanjeetsuhag good start.

How far along is the CesiumJS implementation? That will help inform any corner cases or implementation tips for this spec.

pjcozzi · 2021-05-06T23:44:23Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+<!-- omit in toc -->
+## Dependencies
+
+Written against the draft of [OGC GeoPose Standard 1.0](https://github.com/opengeospatial/GeoPose/tree/main/standard).


The intent of the Dependencies is to state, for example, if an extension requires another extension and to state what version of glTF is requires, e.g.

Written against the glTF 2.0 spec.

So OGC GeoPose is not a dependency, but it may be a normative reference. I haven't looked at GeoPose or this extension closely enough yet to know for sure.

pjcozzi · 2021-05-06T23:45:04Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+
+## Overview
+
+This extension to glTF enables static positioning and orienting of models on the Earth.


This needs more context and use cases. Probably one to two paragraphs to properly motivate.

pjcozzi · 2021-05-06T23:47:05Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+
+GeoPose 1.0 is an OGC Implementation Standard for exchanging the location and orientation of real or virtual geometric objects (*Poses*) within reference frames anchored to the earth’s surface (*Geo*) or within other astronomical coordinate systems.
+
+This extension implements [Standardization Target 2: Basic-Euler](https://github.com/opengeospatial/GeoPose/blob/main/standard/standard/standard/clause_7_normative_text.adoc#standardization-target-2-basic-euler) in the OGC GeoPose 1.0 Standard.


Perhaps this means that EXT_geopose is too broad of an extension name and that we should use something more narrow. This is something to discuss with the authors of the OGC GeoPose spec - because there could be interest in bringing more of the GeoPose spec into a glTF perhaps via a collection of extensions.

pjcozzi · 2021-05-06T23:51:19Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+
+## Coordinate Systems
+
+This extension uses WGS84([EPSG:4979](https://epsg.io/4979)) as the coordinate reference system for specifying the position with longitude and latitude specified in degrees. Height above (or below) the ellipsoid must be specified in meters. The yaw-pitch-roll is provided as a rotation-only transform from a WGS84 referenced local tangent plane East-North-Up coordinate system..


degrees

Is this consistent with the rest of the glTF ecosystem?

At glance, I see degrees in this vendor extension: https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Vendor/AGI_articulations/README.md#stages

Ah, I probably wrote this years ago. 😄

All angles are in radians.

See https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#coordinate-system-and-units

Ditto for 3D Tiles.

There are a couple benefits to degrees:

Matches the EPSG:4979 definition

Human readable and editable, while not necessarily the primary goal of glTF, could be beneficial for an extension like this

I also think the case could be made that even though coordinates are angles, they are a distinct category that could have special treatment.

pjcozzi · 2021-05-06T23:55:18Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+      "latitude": 25.067,
+      "height": 691.0,
+      "ypr": {
+        "yaw": 0.0,


Diagram would be helpful for yaw pitch roll mapping to east north up.

The spec should also discuss the interaction with positioning a glTF model where the front is +z.

glTF uses a right-handed coordinate system, that is, the cross product of +X and +Y yields +Z. glTF defines +Y as up. The front of a glTF asset faces +Z.

See https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#coordinate-system-and-units

Ah, I see this is basically a duplicate comment with @lilleyse's comment above.

pjcozzi · 2021-05-06T23:55:58Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+}
+```
+
+## Schema Updates


Maybe I missed a TODO list for the spec, but it should have a property reference generated from the JSON schema.

Also add a Known Implementations section; for example, see https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu#known-implementations

pjcozzi · 2021-05-06T23:56:46Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/README.md

+{
+  "extensions": {
+    "EXT_geopose": {
+      "longitude": 46.7,


longitude and latitude bounds should be defined, e.g., [-180, 180] and [-90, 90] (degrees)

pjcozzi · 2021-05-06T23:59:19Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/schema/gltf.EXT_geopose.schema.json

+    },
+    "ypr": {
+      "type": "object",
+      "description": "Rotation-only transformation from a WGS-84-referenced local tangent plane east-north-up coordinate system.",


Perhaps useful to include an appendix in the extension spec on how to compute the transformation matrix.

https://github.com/CesiumGS/cesium/blob/master/Source/Core/Transforms.js#L275

pjcozzi · 2021-05-07T00:01:34Z

extensions/2.0/Vendor/EXT_geopose/0.0.0/schema/gltf.EXT_geopose.schema.json

+      "type": "number",
+      "description": "Heights are in meters above (or below) the WGS84 ellipsoid."
+    },
+    "ypr": {


glTF does not use abbreviations in property names...maybe "ypr" is common enough but this might need to be renamed. Also, perhaps the ypr indirection isn't needed at all, and that yaw, pitch, and roll could be in the top-level object.

I would also prefer a slightly different schema but this intentionally matches the JSON encoding defined in the GeoPose spec.

https://github.com/opengeospatial/GeoPose/blob/main/standard/pdf/geopose_standard.pdf - page 42

Also on page 10:

GeoPose 1.0 JSON encodings are specified via JSON-Schema:2019-9 and most of the requirements are that conforming encoded data objects shall validate against the corresponding schema

@lilleyse there is a discussion point to be add with the glTF community: if this extension should try to strictly follow GeoPose norms or glTF norms. From a glTF ecosystem perspective, consistency throughout that ecosystem may be preferred, but it is to be discussed. There may also be lessons learned from bringing the XMP spec to glTF.

@sanjeetsuhag could you please start a TODO checklist at the top of this GitHub issue.

pjcozzi · 2021-05-07T00:06:37Z

extensions/2.0/Vendor/EXT_geopose/README.md

@@ -0,0 +1,8 @@
+# EXT_geopose


Are we sure this changelog is necessary? It is not customary.

We have been following this convention (ex: 3DTILES_implicit_tiling, 3DTILES_metadata, EXT_feature_metadata) to provide direct references and changelogs for specifications that may depend on these extensions.

@sanjeetsuhag for this extension it's fine to not have a changelog. We should consider removing the landing pages for those as well.

janerivi · 2021-06-09T12:31:42Z

By the way the "default" Basic GeoPose intends to use quaternions (not angles) defined on the local tangent plane of the geolocataion using East North Up that might be more convenient for a graphics engine. The correspondance of axis of the kartesian coordinate system at the tangent plane is East North Up -> X Y Z. Schema can be found on page 40 (as of todays writing) https://github.com/opengeospatial/GeoPose/blob/main/standard/pdf/geopose_standard.pdf

lilleyse · 2021-08-30T23:52:30Z

Synced this branch with 3d-tiles-next and removed the landing page.

lilleyse reviewed May 6, 2021

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pjcozzi requested changes May 7, 2021

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pjcozzi mentioned this pull request May 7, 2021

Adds EXT_geopose extension KhronosGroup/glTF#1980

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sanjeetsuhag changed the title ~~Adds EXT_geopose extension~~ Adds EXT_geopose_basic_euler extension May 11, 2021

lilleyse force-pushed the 3d-tiles-next branch from b3f48c2 to 3bf5af9 Compare August 30, 2021 22:49

lilleyse force-pushed the geopose branch from c13ddb9 to d011c32 Compare August 30, 2021 23:48

lilleyse force-pushed the 3d-tiles-next branch from 2996cb7 to f34bd1a Compare September 26, 2021 13:49

sanjeetsuhag and others added 12 commits September 26, 2021 09:50

Adds initial draft of CESIUM_geopose v0.0.0

7583998

Fixes typo

924dfa7

Adds table of contents

02eafcb

Adds note of OGC GeoPose extension being a draft

3fb442f

Rename to EXT_geopose

5fc42f7

Improves top README

e0993e6

Fix extension name

8393246

Fix extension name in 0.0.0

9f67b43

Fix schema name

58e1696

Renames extension to EXT_geopose_basic_euler

24ae963

Remove landing page

8c50bb1

Remove version number

5030a2a

lilleyse force-pushed the geopose branch from 7673fbb to 5030a2a Compare September 26, 2021 13:50

lilleyse mentioned this pull request Oct 20, 2021

Adds ModelExperimental3DTileContent, B3dmLoader, removes Cesium3DTileContentFeatureTable CesiumGS/cesium#9873

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lilleyse mentioned this pull request Nov 15, 2021

Store longitude and latitude in degrees instead of radians CesiumGS/3d-tiles#387

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Adds EXT_geopose_basic_euler extension #5

Adds EXT_geopose_basic_euler extension #5

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lilleyse commented Aug 30, 2021


		## Coordinate Systems

		This extension uses WGS84([EPSG:4979](https://epsg.io/4979)) as the coordinate reference system for specifying the position with longitude and latitude specified in degrees. Height above (or below) the ellipsoid must be specified in meters. The yaw-pitch-roll is provided as a rotation-only transform from a WGS84 referenced local tangent plane East-North-Up coordinate system..

	This extension uses WGS84([EPSG:4979](https://epsg.io/4979)) as the coordinate reference system for specifying the position with longitude and latitude specified in degrees. Height above (or below) the ellipsoid must be specified in meters. The yaw-pitch-roll is provided as a rotation-only transform from a WGS84 referenced local tangent plane East-North-Up coordinate system..
	This extension uses WGS84 ([EPSG:4979](https://epsg.org/crs_4979/WGS-84.html)) as the coordinate reference system for specifying the position with longitude and latitude specified in degrees. Height above (or below) the ellipsoid must be specified in meters. The yaw-pitch-roll is provided as a rotation-only transform from a WGS84 referenced local tangent plane East-North-Up coordinate system..


		## Overview

		This extension to glTF enables static positioning and orienting of models on the Earth.


		GeoPose 1.0 is an OGC Implementation Standard for exchanging the location and orientation of real or virtual geometric objects (Poses) within reference frames anchored to the earth’s surface (Geo) or within other astronomical coordinate systems.

		This extension implements [Standardization Target 2: Basic-Euler](https://github.com/opengeospatial/GeoPose/blob/main/standard/standard/standard/clause_7_normative_text.adoc#standardization-target-2-basic-euler) in the OGC GeoPose 1.0 Standard.

Adds EXT_geopose_basic_euler extension #5

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