Using glTF for streaming CityGML 3D City Models
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CREATE MAINTAIN PUBLISH Using glTF for streaming CityGML 3D City Models Web 3D 2016 Anaheim CA June 23 2016 Arne Schilling, Jannes Bolling, Claus Nagel virtualcitySYSTEMS GmbH Berlin, Germany
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Transcript of Using glTF for streaming CityGML 3D City Models
CREATE MAINTAIN PUBLISH
Using glTF for streaming CityGML 3D City Models
Web 3D 2016 Anaheim CAJune 23 2016
Arne Schilling, Jannes Bolling, Claus NagelvirtualcitySYSTEMS GmbHBerlin, Germany
Arne Schilling - Using glTF for streaming CityGML 3D City Models2
GDI Integration/Use Cases Technical Requirements Approach Data Preparation Batched 3D Model 3D Tiles Performance Tests Conclusions
Outline
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GDI Integration
ETL Processes
VisualizationSTEP
Simulation
Data Access
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Use Cases
Online visualization of highly detailed city models
Web Mapping projects Analyzing 3D building data sets Public Relations / development projects Planning underground infrastructure Analyzing urban simulation results
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Easy browser integration Lightweight 3D viewer based on HTML5 / CSS / WebGL No plugins! Java/Flash/Silverlight not an option. Solution must run on mobile devices as well Efficient Streaming Object identification Access to object properties Custom styling based on object properties Display of buildings, trees, street light, custom terrain,
underground networks, POIs Royalty-free formats preferred
Technical Requirements
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Cesium Framwork for Rendering• Open Source 3D web globe and Javascript API (
http://cesiumjs.org)• Based on open standards (WebGL, glTF)• Support for geo-services: WMS, WMTS , TMS, OSM, Bing
Maps etc.• OpenLayers integration for Vector overlays• Support for custom object layers• Shadow mapping recently added• Supports object identification and object attributes via
sophisticated B3DM format (GIS features) Data Management in 3DCityDB
• Based on CityGML open OGC standard• Semantic information • Supports buildings, bridges, vegetation, street furniture,
tunnels etc.
Approach
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CityGML to glTF B3DM conversion using custom converter• Integrated into online publishing platform
Data Preparation
Spatial Subdivision
Coordinate Transformation
Appearance Filtering
Triangulation
LoD Filtering
Texture Atlas Generation 3D Tiles / B3DM files
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Currently being developed Batches allow defining features by vertex attributes rather than
geometries• -> Mesh configuration independant from objects ->
performance boost• -> Allows to create more efficient texture atlas
Features can still be highlighted & queried Batch Ids are linked to an attribute table
B3DM - Batched 3D Model
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Batched 3D Model (B3DM) Instanced 3D Model (I3DM) Point Clouds (PNTS) Composite (CMPT)
3D Tiles
B3DM for buildings Trees as I3DM
Point cloud as PNTS
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3.180 buildings 64.000 Polygons 50.000 Texture Images
Performance Tests
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Performance Tests – scene elements
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Performance Tests – File Sizes
60 MB
Image Data
Numbers in MB
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Conclusions
B3DM/glTF great for streaming 3D city models• Small files sizes• Can be parsed quickly by JavaScript clients• Optimal packaging
Handling of multiple LODs difficult Performance bottleneck is updating models in JavaScript
clients (Cesium)
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Berlin Economic Atlas• http://www.businesslocationcenter.de/wab/maps/main
/ Berlin virtualcityMAP demo
• http://hosting.virtualcitysystems.de/demos/berlin/vcm/index.html?lang=en
Berlin Open Data download portal• http://www.businesslocationcenter.de/berlin3d-downlo
adportal/
Demo Links
