3D Portrayal Interoperability Experiment
Benjamin Hagedorn Computergraphische Systeme
Hasso-Plattner-Institut an der Universität Potsdam
Workshop 3D-Stadtmodelle 2011
Bonn, 9. November 2011
OGC & 3DIM
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What is the Open Geospatial Consortium?
The OGC
• A non-profit, international voluntary consensus standards organization that is leading the development of standards for geospatial services that support interoperable solutions that "geo-enable" the Web, wireless and location-based services and mainstream IT.
• Facilitates a consensus process in which Members from currently 424 organizations collaborate to define and maintain OGC standards.
• 35 Adopted standards.
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http://www.opengeospatial.org
Open Geospatial Consortium
The OGC
• The Open Geospatial Consortium (OGC) is an international industry consortium of 421 companies, government agencies and universities participating in a consensus process to develop publicly available interface standards. OGC® Standards support interoperable solutions that "geo-enable" the Web, wireless and location-based services and mainstream IT. The standards empower technology developers to make complex spatial information and services accessible and useful with all kinds of applications.
http://www.opengeospatial.org
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Open Geospatial Consortium
The OGC Vision
• To achieve the full societal, economic and scientific benefits of integrating electronic location resources into commercial and institutional processes worldwide.
The OGC Mission
• To serve as a global forum for the development, promotion and harmonization of open and freely available geospatial standards …
Urban Model of Berlin based on OGC CityGML
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OGC Domain Working Groups (Aug-8-11)
3D at the OGC
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An interest or focus in 3D content modeling, sharing, and integration/fusion
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3D Information Management DWG
The 3DIM Mission
• “A great deal of technical innovation has been accomplished in the areas of CAD, AEC, geospatial and 3D visualization, and urban simulation. A variety of products, information and services abound in each of these environments. This work is of interest to the Geospatial community in that there is a growing need for technologies and information to interoperate flexibly and fluidly between these domains to support a range of vital services and decision support needs. The CAD/GIS WG will focus its efforts on identifying and acting on opportunities to improve interoperability geospatial data and services across these domains.”
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3DIM DWG - Overview
3DIM History
• Formed in 2005 as the CAD/GIS Working Group
• Changed name to 3D Information Management Domain Working Group in 2007 to better reflect the diversity of work in the group
• Initiated CityGML Standards Working Group in 2007
• Initiated Oblique Imagery Domain Working Group in 2009
• 3D Portrayal Interoperability Experiment started in May 2011
• IndoorGML Standardization in preparation
Activities
• Devise/Initiate architecture for open interoperable 3D services
• Advance Discussion Papers and Best Practices
• Participate in Testbeds
• Build on industry partnerships
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3DIM DWG - Relationships
buildingSMART alliance (MoU)
• Development of IFC, the major, open standard for Building Information Modeling (BIM)
• AECOO-1 Testbed: Discussion Paper released
• BIM-GIS Information Exchange Project
Special Interest Group 3D (MoU)
• German organization responsible for initial CityGML format
• MoU signed
W3C Point of Interest Working Group
• Mission is to develop a technical spec for the representation of "Points of Interest" information on the Web
Web 3D Consortium (MoU)
• X3D: ISO Graphics Standard for 3D on the Web
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Service-based 3D Portrayal
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OGC 3D Standards
OGC Geography Markup Language (GML)
• XML-based language for encoding geographic information to be stored and transported over the Internet
• Defines both the 2D and 3D geometry and properties of objects that comprise geographic information.
CityGML
• Application independent Geospatial Information Model for virtual 3D city models and 3D landscape models
• Comprises different thematic areas(buildings, vegetation, water, terrain, traffic etc.)
KML Encoding Standard
• XML for geographic visualization on 2D and 3D Earth browsers
• Features for display: placemarks, images, polygons, 3D models, text, etc.
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3D Portrayal Services
Separation of rendering concerns; examples of services and formats:
KML
CityGML
X3D
GML
WFS WMS
WVS
W3DS
GoogleEarth
DP
DP
SLD for WMS
X3DViewer
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3D Portrayal Services
Missing Link
• Proprietary 3D portrayal solutions available for Perspective Street Views, Virtual Globes (commercial and open source)
• However, extensibility and interoperability are limited and projects (e.g. 3D City Models) depend on the business model of existing platforms
• By opening the 3D portrayal interfaces it becomes possible to exchange servers and clients in a flexible way
• 3D visualization systems have different requirements than full desktop GIS
We need a “Map Server for 3D”
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OGC Candidate 3D Portrayal Standards
Web 3D Service and Web View Service
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OGC Candidate Standard: Web 3D Service
Web-based, Graphics-Based Provision of and Access to Virtual 3D Worlds
• Geodata is delivered as scenes that are comprised of display elements, optimized for efficient real time rendering at high frame rates
• It can be used for web applications and datasets that are too big for being stored in single files.
• Streaming allows effective fly-throughs.
• All features supported by web 3D standards (VRML, X3D, COLLADA, KML) can be exploited.
www.w3ds.org
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OGC Candidate Standard: Web View Service
Web-based, Image-Based Provision of and Access to Virtual 3D Worlds
• Server-side model management and 3D rendering
• Generation of images of views on the 3D model and transfer to viewer clients
• Provides visual, thematic, and geometric information
• Reduces data complexity and rendering complexity for clients
• WVS is a 3D equivalent of 2D map services
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www.webviewservice.org
3DPIE - Setting
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3D Portrayal Interoperability Experiment
Main focus on Web 3D Service and Web View Service
• 3DPIE tests server-side issues and client-server interaction to test the interoperability along the visualization pipeline: Advance and harmonize developments of Web 3D Service (W3DS) and Web
View Service (WVS) candidate standards.
Test the applicability of W3DS-based and WVS-based 3D portrayal approaches for different client platforms, including thick clients, web-based clients, and mobile clients.
Test the compatibility of 3D portrayal based on W3DS and WVS with standards-based data formats, including, e.g., CityGML.
Lower the barriers for the implementation, integration, and usage of 3D portrayal capabilities.
http://www.opengeospatial.org/projects/initiatives/3dpie
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3DPIE – Context
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3DPIE – Questions to Answer
Questions to Answer
1. Can the draft service candidates of WVS and W3DS adequately support the web-based management, portrayal, and exploration of environmental and urban 3D geodata?
2. Can the W3DS and WVS specifications be further harmonized to provide a more common interface to 3D portrayal capabilities and to support their potential integration and combination?
3. What are best practices for the application of the various 3D portrayal approaches, including graphics-based 3D portrayal (e.g., through W3DS) and image-based 3D portrayal (e.g., through WVS)?
4. What are best practices for the application of the various 3D geodata formats and 3D graphics data formats including CityGML, X3D, KML, COLLADA, and others?
5. How to exploit W3DS and WVS from various client platforms, including thin-clients, web-based clients, and mobile clients?
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3DPIE – Use Case
„Urban Planning“ as a major Use Case
Examples of using 3D portrayal within the urban planning process:
Demand, Conceptualization
Selection of best submission
Constraints
Decision
Engineering
Construction
Underground Eploration
Public participation
Subsurface Structures, Geology
Architectual competition Urban Development Plan, Zoning
CAD, BIM
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3DPIE – Participants
Participants (including 3 Web 3D Cons. members)
• Bitmanagement
• CACI
• Fraunhofer IGD
• GIScience at the University Heidelberg
• Hasso-Plattner-Institut at the University Potsdam
• IGG at Technical University Berlin
• Institute Geographic Nationale (IGN)
• LSIS at Aix-Marseille University
• MOVES Institute at the Naval Post Graduate School
• Virginia Tech
Additionally, many OGC Members are observing the 3DPIE
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3DPIE – Workplan
Work Item 1: Data Integration
• Ex. #1A: Import raw data into W3DS
• Ex. #1B: Import raw data into WVS
Work Item 2: Service Integration
• Ex. #2A: Integration of W3DS data in WVS client
• Ex. #2B: Integration of WVS images in W3DS client
• Ex. #3A: Seamless integration of multiple W3DS in a client
• Ex. #3B: Overlay images from multiple WVS in a client
Work Item 3: Service Delivery
• Ex. #4A: Web-based portrayal through W3DS
• Ex. #4B: Web-based portrayal through WVS
• Ex. #5A: Mobile 3D graphics from W3DS
• Ex. #5B: Mobile perspective images from WVS
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Architecture
3DPIE Architecture
Data Integration Service Integration, Service Delivery
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Schedule
3DPIE Schedule
• Kickoff on 26 May 2011
• Intended duration: 5 months
• Planned to have results ready for the OGC TC Meeting in Brussels in November 2011
June July August September October
Demonstration and
Report
Work Item 1: Data Integration
Work Item 2: Service Integration
Work Item 3: Service Delivery
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November
3DPIE – Experiments & Results
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Data Integration
Data Formats
• CityGML
• Keyhole Markup Language Geodata description language
OGC Standard since 2008
• Collada XML-based open exchange format for data, e.g., 3D geodata
• X3D
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Data Integration
X3D Extensible 3D Graphics Format
• Scenegraph-based 3D graphics data exchange format
• Successor of VRML Standard
• Developed by the Web 3D Consortium (MoU with OGC)
• W3C Standard for 3D content in the Internet
• Variants X3D/VRML
X3D/XML
X3DB (binary X3D)
• Standardized by ISO
• X3DEarth provides a set of geodata-related Nodes:
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GeoDoordinate GeoLocation GeoLOD GeoMetadata GeoOrigin GeoPositionInterpolator GeoProximitySensor GeoTouchSensor GeoTransform GeoViewpoint
Data Integration
Paris Data (Bati3D data)
• Extent: ca. 100 sqkm
• CityGML terrain + LOD2 buildings
• Fully textured (Texture Atlases)
• Provided in 446 tiles (500*500 m)
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Data Integration
Mainz Data
• Layers Gelaende
Gebaeude (LOD1)
sewage_duct
Mainz data available only through the CityServer3D W3DS
Additional planning data
• Planning data that include additional building that are partially textured buildings
• LOD2 for Münsterplatz in separate layer "MuensterplatzLOD2“
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Data Integration
Berlin/Potsdam Data Sets
• Three example data sets “Gasometer”
• 430 Buildings in LOD2
• Textured
“24_24”
• 233 Buildings in LOD2
• Textured
Potsdam
• 97 Buildings in LOD2
• Availale as CityGML
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Data Integration
OpenStreetMap Data
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Data Integration
Data and Servers
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IGG W3DS
CityServer3D W3DS
HPI 3D Server WVS
OSM-3D W3DS
Images
KML, Collada, X3D, HTML5
KML
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Berlin Data (CityGML)
Paris 3D (CityGML)
Mainz Data (CityGML)
OSM Data
VRML, X3D, KML
Data Integration
Viewers / Clients
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XNavigator
Google Earth
Instant Reality Player
HPI WVS Client
HTML5 Browser
BS Contact Geo Images
KML, Collada, X3D, HTML5
KML, KMZ/Collada
VRML, X3D, KML
Data Integration
Preprocessing and integration of 3D city models
• Preprocessing of the large data sets
• Handling and management of massive 3D city models (large storage required, large file numbers, texture handling)
• Spatial organization and
• Generation of graphical elements
• Rendering of views on large 3D City Models (WVS)
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Data Integration
IGG W3DS
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Paris 3D (CityGML)
3DCityDB Importer
3DCityDB
3DCityDB Exporter
Tile Cache
KMZ_collada
KMZ_geometry
IGG W3DS
refers to KMZ files through KML-NetworkLinks
KML master file
Data Integration
Paris: Massive Textures
• Need to split Texture Atlases to import into 3DCityDB
• Should textures ind raw data be represented and delivered as texture atlases?
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Data Integration
CityServer3D
• Fraunhofer updated CityServer3D to implement W3DS 0.4.0
• Specific operations can be mapped to W3DS operations GetTileDefinition
GetScenario
• Integrated and provided Paris data set
Mainz data
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Data Integration
Data Integration Experiments
• Importing Paris data set into IGG Web 3D Service
• Importing Berlin data set into IGG Web 3D Service
• Importing Mainz data set into CityServer3D
• Importing Paris data set into CityServer3D
• Importing Paris data set into HPI WVS
• Processing OpenStreetMap data and importing into OSM-3D
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Service Integration & Delivery
Approache for Service Delivery
• An integrated client consumes one or more service capability documents
• File-based integration/combination
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Viewer Master File
Service
Service
Service
Client
Service
Service Capabilities
Capabilities
url
url
url
Service Integration & Delivery
Example: Portrayal of Paris data from IGG W3DS
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W3DS export to KML and integration with Google Earth
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IGG – W3DS
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STYLES=geometry STYLES=textured
Berlin
IGG – W3DS
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Paris
small projected region: STYLES=geometry
large projected region: STYLES=textured
IGG – W3DS
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Serving Large City Models
Large scale models require
• Spatial organisation of geodata / graphics data
• Streaming this data to a consumer
Fundamental questions
• What does a client know about the spatial organisation of a scene?
• What does a client have to do?
Two approaches for dynamic data integration
• Include knowledge about spatial organization in the data, e.g., as a scene graph Care free package provided to a viewer client
• Provide a specific data tiling mechanisms through service interface
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Serving Large City Models
W3DS specific Tiling Mechanism
• W3DS advertises Tiling in metadata document
Master Document with Raster Specification
• A master document refers geometry tiles directly
• Problematically for large scene Worldwide coverage would require a very large raster
Adaptive, Dynamic Refinement
• Special scene graph nodes can group child nodes (group nodes and geometry nodes)
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Serving Large City Models
W3DS Tiling Mechanism
• W3DS advertises TileSet element in service meta data document
• Tile are requested via W3DS GetTile operation
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Serving Large City Models
GetScene-based transparent Tiling in W3DS
• W3DS KML export via GetScene
• Handling arbitrary bounding boxes in requests
• Based on a layers MaxScaleDenominator
• Client retrieves a valid documents
Example
• MaxScaleDenominator=300
• Requested bounding box is 400 * 500 m
• Results in a quadtree of 4 tiles
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Requested Area Responsed Tiles
Serving Large City Models
GetTileDefinition
• http://host/cs3d/Controller?do=GetTileDefinition&template=entrypoint&surface=mainz_stadt
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Serving Large City Models
GeoLOD nodes in X3D
• GeoLOD node provides a terrain-specialized form of the regular LOD node rootUrl or rootNode are used to define geometry shown at default level
child1Url ... child4Url fields define quadtree links to children subscenes
geoSystem defines geospatial coordinate system
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Serving Large City Models
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<NetworkLink>
<Region>
<LatLonAltBox>
<Lod>
<Link> ... to W3DS, e.g., to GetScene operation
... more NetworkLinks
Serving Large City Models
Tile Generation
• Raster tiles could be created „on the fly“
• Raster tiles could be preprocessed and cached
Impact on W3DS Service Specification.
• Make the implementation of W3DS Tiling mechanism optional
• Use format‘s tiling mechanisms if available
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Height References
Dealing with Height References
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Height References
Dealing with Height References
• Object locations needs to fit the terrain that is used by a 3D viewer
• Problematically in a distributed 3D portrayal system with distributed and independently generated 3D data
• Approaches Deriving the terrain height, e.g., via Google Elevation API
• Example request: http://maps.google.com/maps/api/elevation/xml?locations=39.7391536,-104.9847034&sensor=false
Use language features to position 3D objects relative to a terrain surface
• KML: Location, e.g., “relativeToHeight”
• X3D: GeoLocation
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Further Discussions
• Should we talk about data „layers“ in 3D portrayal or do we rather handle FeatureTypes?
• Features below the terrain are not visible in Google Earth …
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WVS-based Visualization
WVS requires Server-side Rendering
• Graphics data needs to be highly optimized
• Fast access to texture data and large memory required for efficient rendering servers
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WVS-based server-side 3D rendering
WVS-based Visualization
Displaying WVS imagery in Google Earth
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Web-based 3D Portrayal
X3DOM City Viewer im Web Browser
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Mobile 3D Portrayal
X3DOM City Viewer im Web Browser
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Mobile 3D Portrayal
BS Contact on IOS 5
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Mobile 3D Portrayal
WVS-based mobile client
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Conclusions
Some of the 3DPIE Results
• Demonstration and discussion of different approaches for 3D geodata processing, integration, and visualization
• New implementation of the IGG W3DS
• CityServer3D was adapted to latest W3DS specification
• Extension of the Xnavigator client to consume multiple W3DS capability documents
• Increasing conformance of service implementation
• Increasing conformance of data format implementations
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Conclusions
Next Steps / Future Work
• Tiled WVS?
• Test and further develop feature data access
• How should the GetFeatureData operation work?
• Navigation and Interaction with portrayed data
• Extension of 3DCityDB to export X3D
• W3DS / WVS Standardization ?!
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Contact
Benjamin Hagedorn [email protected]
Prof. Jürgen Döllner [email protected]
Computer Graphics Systems Hasso-Plattner-Institut for Software Systems Engineering at University of Potsdam http://www.hpi3d.de
Arne Schilling [email protected] GIScience, University of Heidelberg www.geog.uni-heidelberg.de/giscience.html Volker Coors [email protected] University of Applied Sciences, Stuttgart http://www.hft-stuttgart.de
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