Publication Date: 2020-10-22

Approval Date: 2020-09-23

Submission Date: 2020-08-28

Reference number of this document: OGC 20-031

Reference URL for this document: http://www.opengis.net/doc/PER/3DT-Summary

Category: OGC Public Engineering Report

Editor: Tim Miller, Gil Trenum, Ingo Simonis

Title: 3D Data Container and Tiles API Pilot Summary Engineering Report

OGC Public Engineering Report

COPYRIGHT

Copyright © 2020 Open Geospatial Consortium. To obtain additional rights of use, visit http://www.opengeospatial.org/

WARNING

This document is not an OGC Standard. This document is an OGC Public Engineering Report created as a deliverable in an OGC Interoperability Initiative and is not an official position of the OGC membership. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an OGC Standard. Further, any OGC Public Engineering Report should not be referenced as required or mandatory technology in procurements. However, the discussions in this document could very well lead to the definition of an OGC Standard.

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1. Subject

This Engineering Report summarizes the purpose and key results of the 3D Data Container and Tiles API Pilot, an OGC Innovation Program initiative conducted between October 2019 and July 2020. In the context of both existing and emerging 3D and 2D standards, the focus of the Pilot was on the exchange and visualization of 3D data using open standards.

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2. Executive Summary

A variety of solutions and standards co-exist to access and transfer 3D geospatial content over the internet (e.g. 3D Tiles, I3S, glTF, CDB, CityGML). These solutions were developed for various technical and commercial reasons. They use different distribution mechanisms and are optimized for particular user requirements and bandwidth situations (e.g. image stream, scenes, or raw vector data delivery). As each of these co-existing solutions binds the user to a particular approach, it is challenging to access a variety of 3D content from different providers. The 3D Data Container and Tiles API Pilot addressed this challenge. The Pilot achieved its goal to develop a resource model and corresponding Application Programming Interface (API) to integrate various approaches into a single, open standards based solution. The developed GeoVolumes API and 3D Container resource model allow efficient discovery and access of 3D content based on a space-centric perspective.

The goal of the 3D Data Container and Tiles API Pilot was not to replace existing APIs and distribution models for 3D data, but to develop an integration concept for existing OGC 3D delivery standards to:

  • support smooth transitions between 2D and 3D environments;

  • allow applications to get 2D, 2.5D, and 3D resources; and

  • enable 3D bounding volumes to support multiple types of 3D content.

To achieve these goals, the Pilot developed a 3D geospatial data container and a corresponding draft OGC API - GeoVolumes providing browse and query access to 3D geospatial content. GeoVolumes (aka 3D Containers) can be hierarchically defined with nesting support. The 3D data resources supported by the GeoVolumes API include feature geometries, feature attribute values, elevation models, texture data, and other resource types. The API provides both link-follow and bounding-box query methods of access to 2D and 3D content in a manner independent of the underlying data store. Multiple standard geospatial distribution formats such as 3D Tiles, I3S, CDB, and CityGML are supported for streamed data delivery by means of the GeoVolumes API.

summary
Figure 1. Client connecting to various offerings in multiple formats through single API

Multiple data server and client implementations were developed during the Pilot in order to test interoperable 3D content delivery via the GeoVolumes API. The API was defined using the OpenAPI 3.0 definition language and conforms to the building blocks of the draft OGC API - Common – Part 1: Core specification. Thus, the Pilot developed and tested the GeoVolumes API in order to advance open standards-based and unified approaches for delivering 3D content using state of the art API practices that work across different data formats, streaming protocols, and model types.

This summary first outlines a high-level architecture with different distribution levels, bandwidth options, and required capabilities. This approach helps to better understand where the GeoVolume (also known as 3D Container) and its corresponding API actually exist and integrate with other established or emerging standards. The summary then briefly introduces differences between existing solutions to further illustrate the challenge described above.

Once the context is set, the summary outlines the technical challenges that had to be addressed, defines the GeoVolume/3D Container (3DC), describes its capabilities and constraints, and introduces the API that uses the GeoVolume as its resource model. The summary describes how wide-spread tools have been used to document the building blocks of the API and provides further insights into taken design decisions using statements from the Pilot participants on initial challenges, tested approaches, and final solutions. The summary briefly illustrates the developed prototypes and ends with an assessment of the commercial potential of the proposed solutions, their future path in the standardization process, and required next steps towards a fully interoperable, space-centric 3D data exchange and exploration environment.

From a standardization perspective, the Pilot developed a draft API and resource model that have been proven mature enough to be introduced to OGC’s Standards Program. The next steps now include generating a new OGC Standards Working Group (SWG), which requires defining the SWG charter. Once the charter is approved by the OGC Technical and Planning Committees (TC & PC), the SWG starts with the consensus based standard development process and eventually recommends to the Technical Committee the release of the final Standard to the public.

It is important that additional integration tests and real-world deployment demonstrations further explore the potential of the GeoVolumes API, resolve any outstanding interoperability issues, and explore best practices for the organization of GeoVolumes within different domains and disciplines. Several of these tests are scheduled to begin in September 2020.

2.1. Document contributor contact points

All questions regarding this document should be directed to the editor or the contributors:

Contacts

Name Organization Role

Ryan Gauthier

US Army Geospatial Center

Sponsor/Contributor

Jeff Harrison

US Army Geospatial Center

Sponsor/Contributor

Tom Myers

US Army Geospatial Center

Sponsor/Contributor

Tim Miller

Leidos

Editor

Gil Trenum

Leidos

Editor

Ingo Simonis

OGC

Editor

Josh Lieberman

OGC

Contributor

Rob Jones

Helyx

Contributor

Matthew Knight

Helyx

Contributor

Anneley Hadland

Helyx

Contributor

Jerome Jacovella-St-Louis

Ecere

Contributor

Michala Hill

Cognitics

Contributor

Nacho Correas

Skymantics

Contributor

Volker Coors

Steinbeis

Contributor

Thunyathep Santhanavanich

Steinbeis

Contributor

Kevin Ring

Cesium

Contributor

2.2. Foreword

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The Open Geospatial Consortium shall not be held responsible for identifying any or all such patent rights.

Recipients of this document are requested to submit, with their comments, notification of any relevant patent claims or other intellectual property rights of which they may be aware that might be infringed by any implementation of the standard set forth in this document, and to provide supporting documentation.

3. High-Level Architecture

The high-level architecture is built around the needs of the various entities ('A'), ('B'), and ('C') in an enterprise as illustrated in the Figure 2. The three entities differ in the amount of data that can be stored and processed, the available bandwidth for data transport, the multiplicity of supported analytics, and the offered data products. Despite these differences, it was the goal of this Pilot to develop a model that allows offering, discovering, requesting, and processing data at each entity using a common single API on top of a single organizational model of 3D data in space. At the same time, this common single API should acknowledge available 3D data format and distribution standards such as 3D Tiles, I3S, CityGML, or CDB to ensure that customers can retrieve 3D data in the optimal format for their respective tasks.