Publication Date: 2021-11-08

Approval Date: 2021-09-21

Submission Date: 2021-08-30

Reference number of this document: OGC 21-058

Reference URL for this document: http://www.opengis.net/doc/PER/ISG-Sprint-Yr2

Category: OGC Public Engineering Report

Editor: Leonard Daly, Rollin Phillips

Title: Interoperable Simulation and Gaming Sprint Year 2 Engineering Report


OGC Public Engineering Report

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Copyright © 2021 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 Innovation Program 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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Table of Contents

1. Subject

The OGC Interoperable Simulation and Gaming Year 2 Sprint advanced the use of relevant OGC and Khronos Group [1] standards in the modeling, simulation, and training communities through capability development, compatibility testing, and gap analysis. Of particular interest was the use of glTF models, game engines, and 3rd-party mobile device libraries for the display and interaction with data using OGC APIs.

2. Executive Summary

The Interactive Simulation and Gaming (ISG) Year 2 Sprint ("Sprint") was undertaken by OGC under the OGC Innovation Program to investigate and analyze the capability of using a combination of OGC and non-OGC standards:

  • glTF [2] in particular;

  • Widely adopted 3rd party display engines (Unity and Unreal Engine in particular);

  • OGC current and upcoming Standards (in particular GeoVolumes, GeoPose, SensorThings, and MovingFeatures); and

  • Future alignment with emerging new technologies and CDB.

The primary non-OGC standard under consideration was glTF. The use of glTF was also successfully investigated in ISG Year 1 Sprint. 3rd-party display engines included not only Unity and Unreal Engine, but the ARCore [3] and ARKit [4] mobile device augmented reality libraries.

The OGC existing and emerging standards of interest include CDB (1.x and 2.0), 3D GeoVolumes, GeoPose, SensorThings, and MovingFeatures. CDB is of special interest in that an optional goal is alignment of new technology with a future release of CDB, especially using glTF as an additional modeling format.

OGC has partnered with The Khronos Group on two Sprints (Year 1 and Year 2). Both organizations worked diligently to advance glTF to meet the needs of current and future users while ensuring support to previous activities. Both organizations are investing in the development of new and future technologies.

2.1. Operation

The period of performance for the Sprint was two months from kickoff to submission of Sprint participant reports. The actual coding effort was scheduled for two weeks in June 2021 on either side of the June quarterly OGC Member Meeting. The entire effort was planned and executed virtually.

Two CDB structured datastores were made available to all participants - the San Diego and New York CDB datastores. Additionally, the participants accessed eight other datasets. The use of other datasets was unexpected and the list is documented in Appendix C: Datasets Used in ISG Year 2 Sprint. The Sprint participants were (in alphabetical order): Cesium, Ecere, FlightSafety, InfoDao, SimBlocks.io, and Steinbeis. All participants were OGC members and had prior experience participating in OGC projects.

2.2. Accomplishments

Most of the Sprint participants partnered with at least one other participant for some portion of their work. The participants addressed a wide-range of issues described in the OGC ISG Year 2 Sprint: Call for Participation (CFP) [5]. This is shown in Table 4. The wide range of problems addressed plus an agreement on cross-over snags provided confidence that the problem-space was covered and individual results are generally applicable.

  • The data conversion process between various formats used by CDB datastores is mostly understood. Future efforts should be focused on operational improvements for specific scenarios.

  • glTF is sufficiently capable to support static GeoTypical and GeoSpecific models contained in a CDB datastore.

  • Game engines (Unreal Engine and Unity) were demonstrated to work with data based on an existing OGC encoding standard.

  • OGC structured and encoded data and APIs can be integrated into mobile apps using ARCore and ARKit.

  • Seamless and smooth transitions can be done when moving from the outdoors to an indoor environment and back out.

2.3. Issues

A few issues were discovered during the Sprint. Mostly these were related to difficulties or differences with third-party applications. One issue may be a result of incomplete 3D Tiles specification or a misunderstanding in a common implementation. All of the issues are documented in Discovered Issues in the Findings chapter. The most important ones are listed below.

2.5. Document contributor contact points

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

Contacts

Name Organization Role

Leonard Daly

Daly Realism representing Khronos Group

Editor & Contributor

Rollin Philips

Open Geospatial Consortium

Editor & Contributor

Sean Lilley

Cesium

Contributor

Sam Suhag

Cesium

Contributor

Michala Hill

Cognitics/SOCOM

Sponsor support

Jerome St-Louis

Ecere

Contributor

Diego Caraffini

Ecere

Contributor

Patrick Dion

Ecere

Contributor

Spencer Berg

FlightSafety

Contributor

Ryan Franz

FlightSafety

Contributor

Aaron Williams

FlightSafety

Contributor

Joshua Rentrope

InfoDao

Contributor

Jordan Dauble

SimBlocks.io

Contributor

Glenn Johnson

SimBlocks.io

Contributor

Volker Coors

Steinbeis, HFT Stuttgart

Contributor

Thunyathep Santhanavanich (Joe)

Steinbeis, HFT Stuttgart

Contributor

Athanasios Koukofikis

Steinbeis, HFT Stuttgart

Contributor

Rushikesh Padsala

Steinbeis, HFT Stuttgart

Contributor

Patrick Würstle

Steinbeis, HFT Stuttgart

Contributor

2.6. 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. References

4. Terms and definitions

For the purposes of this report, the definitions specified in Clause 4 of the OWS Common Implementation Standard OGC 06-121r9 shall apply. In addition, the following terms and definitions apply.

3dsMax [6]

A 3D modeling and rendering software application from Autodesk.

● 3D Tiles

A data structure specified in the OGC 3D Tiles Community Standard. See References.

● 3D Tiles Next

Cesium’s proposed next generation of 3D Tiles [7].

ArcGIS [8]

A software platform from Esri that offers capabilities for specifying and applying location-based analytics.

● CDB [9]

The OGC CDB Standard defines a model and rules for structuring a single virtual representation of the earth. This term is sometimes used to refer to a dataset at a particular location (e.g., San Diego CDB).

● CDB X

The next major version of CDB. Work on CDB-X is in progress and many core requirements classes have been specified and documented.

● COLLADA

A 3D model format that supports private extensions.

● CityGML [10]

The OGC open data model and file format for the storage and exchange of virtual 3D city models/data. See References.

● Feature Manipulation Engine

A software application from Safe Software that transforms data and formats.

● GeoPackage [11]

An open, standards-based, platform-independent portable, self-describing, compact format for storing and transferring geospatial information. See References.

● GeoSpecific

A 3D model of an object that has a specific place on Earth. Examples include the Eiffel Tower, the US Capitol, Mt. Rushmore, and many other objects that are unique and may be used to immediately identify a location and with potentially time information.

● GeoTypical

A 3D model of an object whose existence does not identify a location and where the model may be used repeatedly. Examples include trees, most warehouses, and many residential buildings.

● glb

See glTF.

● glTF

The 3D model standard from the Khronos Group. It stands for "graphics language Transmission Format". The V2.0 standard is documented. The standard is in the process of becoming an ISO Standard. A glTF model may be represented in multiple files with the primary file having the extension .gltf; or typically a single file with the extension .glb.

● GNOSIS

Ecere’s geospatial client

● GTModel

See GeoTypical

● One World SDK

SimBlocks.io software development kit for handling geospatial data in the Unity real-time 3D engine.

● OpenFlight [12]

A 3D geometry modeling and scene description language and file format used for real-time visual simulation of 3D terrain features and moving models.

● OpenSceneGraph

An open-source 3D graphics software library used for a variety of application development.

● SensorThings API [13]

An OGC API Standard that defines an open, geospatial-enabled and unified way to interconnect the Internet of Things (IoT) devices, data, and applications over the Web.. See References.

● skp

See Trimble Sketchup.

● TinyGLTF

An open source software library that handles glTF files.

● Trimble Sketchup

A web-based 3D modeling environment that is frequently used for building models.

4.1. Abbreviated terms

  • COTS - Commercial Off The Shelf

  • DCE - Distributed Computing Environment

  • IDL - Interface Definition Language

  • B3DM - Batched 3D Model

  • COTS - Commercial Off The Shelf

  • CName - Colonized Name - an XML term for a particular type of string.

  • DIIL - Disconnected, Interrupted, Intermittent, Low-Bandwidth

  • DIS - Distributed Interactive Simulation

  • DOF(s) - Degrees of Freedom. Full freedom in space has six degrees of freedom - left/right, front/back, up/down, roll, pitch, and yaw.

  • E3D - Ecere’s 3D model format

  • EOS - Earth Observing System

  • FLIR - Forward looking InfraRed

  • HLA - High Level Architecture

  • I3DM - Instanced 3D Model

  • IoT - Internet of Things

  • LOD - Level Of Detail. A highly detailed model may be created to display at reduced detail when the scene camera is far away. The model typically defines the number of levels, the detail shown at each level, and the applicable viewing range.

  • MModels - Moving Models

  • MOVINT - Movement Intelligence

  • NVG - Night vision goggles

  • NGA - GRiD National Geospatial-Intelligence Agency Geospatial Repository and Data Management

  • OSG - OpenSceneGraph

  • PBR - Physically Based Rendering. This is a means for calculating the appearance of a model based on a number of physical parameters including metal-roughness, normals, and transmission. glTF uses this model for rendering.

  • SWIR - Short-Wave InfraRed. The spectrum of electromagnetic energy with wavelength longer than visible red, but shorter than thermal energy. 8

  • TIFF - Tagged Image File Format. This format is used for storing raster graphics images. It is a container format that can store multiple different image formats. Images stored as TIFF files frequently are uncompressed or losslessly compressed. See also Wikipedia - TIFF [14].

  • X3D - Extensive 3D Graphics - an ISO standard for storing, transmitting, and displaying 3D models. See https://www.web3d.org/standards [15] for more details.

  • XR - Extended Reality. This term encompasses the entire spectrum from fully Virtual Reality (everything computer rendered), through Augmented Reality (some objects computer rendered, and composed with camera data), to Real Reality (complete physical space and objects).

5. Overview

Section 6 describes the Foundation of the Sprint. This section includes a description of the scenario options plus all of the material that was provided to the participants.

Section 7 presents the overall Sprint Findings. The discussion includes lessons learned from all participants and the Sprint leadership team in carrying out the Sprint.

Section 8 presents the major Conclusions from the Sprint. This represents the collective knowledge and experience of the Sprint participants and the editors of this Engineering Report.

Sections 9-14 contain the Participant Detailed Reports.

Section 15 contains the consolidated Future Recommendations. Much of this content was gathered from the detailed participant reports.

Appendix A contains a copy of the OGC Standards/Specifications and Scenarios table from https://portal.ogc.org/files/?artifact_id=96942#StandardSpecScenarioCrossReference.

Appendix B contains a copy of the Feature comparison table (or equivalent) with additional notes and comments.

Appendix C contains a list of the datasets that were used by the various participants. Included with the list is additional data describing the reference location, creator, license, and other useful items.

Appendix D contains a list of the display applications that were used by the participants for their results. The table highlights the use of game engines, mobile devices, and 3rd party display applications.

Appendix E contains the document Revision History.

Appendix F contains the document Bibliography.

6. Foundation

6.1. Call for Participation

The OGC ISG Year 2 Sprint: Call for Participation (CfP) [5] was released on 1 April 2021 by the Open Geospatial Consortium (OGC) for the purpose of obtaining proposals from organizations interested in studying data and model handling within the CDB environment. The CfP provided all of the material necessary for organizations to make a proposal for participation either by direct inclusion in the document or publicly available links.

The CfP specified the schedule from kickoff meeting (2 June 2021) through the two spring weeks (weeks of 7 June and 21 June), and the participant final report inputs (31 July). The Sprint was designed from the beginning to be virtual due to pandemic safety restrictions and precautions. The decision was made prior to the release of the CfP.

The schedule for the Sprint work was defined in the CfP and is listed below. Of note is the two non-contiguous weeks of Sprint Work (Mini-Sprint #1 and Mini-Sprint #2) separated by the June OGC Technical Committee Member meeting. The Findings section addresses participant comments on the scheduling. In June, the Sprint participants decided to seek CDB Standards Working Group (CDB SWG) review and comments prior to Technical Committee approval due to the close and important work this Sprint was performing relative to current and future CDB SWG standards work. That addition did not change any contractual arrangements.

Table 1. The master schedule provided to all potential bidders in the CfP. Actual dates substituted for 'TBD'. Comments from the participants are addressed in the Findings section.
Milestone Date  Event

M01

March 31, 2021

Release of Call for Participation (CFP)

M02

April 30, 2021

CFP Proposal Submission Deadline (11:59pm EDT)

M03

May 31

All Participation Agreements signed (OGC will start sending preliminary offers in early May).

M04

June 2

Half-day Kickoff Workshop to be organized as a virtual meeting.

M05

Week of June 7

Mini-Sprint #1 (two scheduled teleconferences plus ad hoc calls as needed).

M07

Week of June 14

Quarterly OGC Member Meeting: submit formal review request to selected OGC WG to review the ER later in the timeline (probably at the Sep. Member Meeting).

M06

Week of June 21.

Mini-Sprint #2.

M08

June 29 & July 6

Dry-Run (29 June) and Stakeholder Demo Event (6 July).

M09

July 31

All participant Engineering Report (ER) contributions submitted.

M10

August 19 & August 30

Near-Final ER draft posted to CDB SWG (19 August) and Pending (30 August) for ISG DWG review.

M11

September 20

Quarterly OGC Member Meeting: ER Publication Vote; Presentation(s) of Final Results.

6.2. Discussion of Scenarios

6.2.1. Overview

The CfP described four possible scenarios. Scenario 1 was split into an A and B part. Participants could choose to work on any combination (to a maximum of three) of these or propose their own within the guidelines established by these scenarios and the rest of the CfP.

6.2.2. Scenario 1

This scenario was related to the conversion of data formats. There were two options that differed in whether the new format was user-requested on-demand or a batch pre-demand process. In both cases the participants were requested to either use OGC Standards and specifications or provide a good reason why OGC standards would not work. Note that in the Sprint scenarios, glTF is considered an OGC format.

Scenario 1A addressed the needs of on-demand conversion from data encoded in one OGC format to another. The results needed to be quantified in terms of response times from initial request to content delivery. The use of existing OGC Standards, APIs, and specifications (OSAS) for this scenario was important to the process. This approach allowed for variations if a good reason could be provided and a recommendation was made for an alternate approach.

Scenario 1B addressed the needs of pre-demand batch conversion from formats found in a CDB dataset to other OGC standard encodings such as GeoPackage. This sub-scenario was designed to quantify the server resources needed for a batch conversion. The conversion process was not required to use existing OSAS; but if an alternative was used, the participant was required to propose a prototype of a new standard. This sub-scenario was also designed to provide guidance on recommended sizing limits of future versions of CDB.

6.2.3. Scenario 2

Scenario 2 was designed to address the issues involved from navigating from the outside environment to inside a building. Traditionally outdoor and indoor models serve different purposes and are not necessarily compatible. CDB defines buildings and their relationship to other objects in the scene. Other OGC Standards (e.g., Indoor Mapping Data Format (IMDF) and IndoorGML) define the interior structures. Moving from the outside of a building to inside a building without losing context has not been a smooth process.

6.2.4. Scenario 3

The integration of animated transportation networks is critical in understanding how a geographic region operates. Scenario 3 required the participant to show transportation networks with animated (moving) vehicles. There was no limitation placed on the network type except that it had to be land or air-based. This scenario also tested gaps in existing OGC Standards and specifications for tracking moving objects.

6.2.5. Scenario 4

The CDB community is considering using glTF as a key modeling format. Therefore, it was necessary to understand the advantages and disadvantages of glTF compared to the existing CDB OpenFlight model format. Preliminary work included in the CfP (and included in Appendix A: Specification / Scenario cross reference table) showed that glTF and OpenFlight were similar in feature capabilities. Participants working on this scenario were to analyze the formats in the context of CDB and specify additional capabilities needed by glTF to functionality replace OpenFlight.

6.3. Material provided to Participants

6.3.1. General OGC Information

Potential bidders were provided with a variety of information including San Diego CDB Dataset, Appendix A: Specification / Scenario cross reference table, and Appendix B: OpenFlight / glTF capability cross reference. Previously used datasets (e.g., New York CDB Dataset) and new datasets (e.g., Austin Dataset) were identified and used by the participants. These are described more fully in Data Sets and Appendix C: Datasets Used in ISG Year 2 Sprint.

6.3.2. Data Sets

The primary data set for the Sprint is known as the San Diego CDB (licensed under the SanGIS Legal Notice - SanGIS GIS Data End User Use Agreement and Disclaimer for Data Released to the Public). This data set was collected using a number of sensors and methods and encompassed nearly all of downtown San Diego and vicinity, including the port, sports stadium, recreational facilities, commercial, and housing areas.