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20251119FOSS4G2025

 20251119FOSS4G2025

FOSS4G2025 Academic Track

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Toshikazu SETO

November 19, 2025
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  1. 2025/11/19 FOSS4G 2025 Academic Track 1/26 Assessment of Display Performance

    and Comparative Evaluation of Web Map Libraries for Extensive 3D Geospatial Data Toshikazu Seto* *: Associate Professor Department of Geography, Komazawa University / OSGeo Charter member Co-Authors: Yohei SHIWAKU, Takayuki MIYAUCHI (Geolonia Inc.), Daisuke YOSHIDA (Osaka Metropolitan University) and Yuichiro NISHIMURA (Nara Women's University) A02 KOMAZAWA UNIVERSITY Visual Identity Guidelines ࿨จϩΰλΠϓ ,ϚʔΫʴ࿨จϩΰλΠϓͷ૊Έ߹Θͤ ͸ɺ ࠨͷछͰ͢ɻ ԣ جຊܗͱ͠ɺ ༏ઌతʹ࢖༻͠·͢ɻ ԣ ϫϯϙΠϯτͳͲɺ ʮԣʯ ͕഑ஔ͠ʹ͍͘ ৔߹ʹ࢖༻͠·͢ɻ ॎ ॎܕαΠϯͳͲɺ ࡉ௕͍഑ஔʹ࢖༻͠·͢ɻ ඞͣϚελʔσʔλΛ࢖༻͍ͯͩ͘͠͞ɻ ࠨهҎ֎ͷ૊Έ߹ΘͤΛ࡞੒͠ͳ͍Ͱ ͍ͩ͘͞ɻ τ౳ʣ ॎ Project PLATEAU CC-BY 4.0, ODC BY and ODbL Virtual Shizuoka CC-BY 4.0
  2. 2025/11/19 FOSS4G 2025 Academic Track 2/26 Outline 1. Research Background

    2. Methodology • Data sources and specifications ・ Data conversion workflows • Libraries and configurations test ・Performance evaluation metrics 3. Results • Overall performance comparison ・Point cloud data analysis • Building model evaluation ・MVT format performance • Visual stability metrics 4. Discussion 5. Findings and Future Works Slide Available▶
  3. 2025/11/19 FOSS4G 2025 Academic Track 3/26 Background & Purpose •

    Digital Technology & Advanced Data Utilization: Crucial for solving urban problems and improving citizen services. • Digital Twins: Virtual representations of physical urban environments with wide- ranging applications, but with associated technical challenges. • 3D City Models (3DCMs) and 3D Point Cloud Data: A growing need in the era of smart cities and key to achieving seamless visualization of city data. • Visualization Performance Analysis: The paper presents a detailed examination of the development and use of 3D city models in Japan. Caprari, G.; Castelli, G.; Montuori, M.; Camardelli, M.; Malvezzi, R. Digital Twin for Urban Planning in the Green Deal Era: A State of the Art and Future Perspectives. Sustainability 2022, 14, 6263. https://doi.org/10.3390/su14106263
  4. 2025/11/19 FOSS4G 2025 Academic Track 4/26 Background of “Project PLATEAU”:

    CityGML • 🎯 Purpose • A digital twin initiative implemented in Japan, aimed at overhauling urban planning processes. • "3D City Model Development": • 200+ cities with 3D city models (2024) • 18+ million building models in urbanized area. • “PLATEAU View” made by Eukarya • "Data Coverage Expansion & Open Sourcing": PLATEAU's progress milestones, including the expansion of data coverage, viewer updates, and increase in open-source repositories. Copyright © 2022 by MLIT. All rights reserved. セマンティクスとジオメトリを統合した唯一のソリッドモデル 10 3D都市モデルのデータ特性 GoogleEarth CityGML Wall Surface Roof Surface Building Solid Station
  5. 2025/11/19 FOSS4G 2025 Academic Track 6/26 Background of “Virtual Shizuoka”:

    LAS/LAZ • 🎯 Purpose • Promote digital transformation in urban planning, hazard and infrastructure management since 2020. • Provide 1:1 scale digital twin data • 🔍 Key Features • 30TB of 3D point cloud data • 6,700 sq km coverage (entire prefecture) • Open datasets under CC BY. • No original viewer: provide 3DDB Viewer by AIST (the National Institute of Advanced Industrial Science and Technology in Japan). • https://gsvrg.ipri.aist.go.jp/3ddb_demo/tdv/index.html
  6. 2025/11/19 FOSS4G 2025 Academic Track 8/26 Research Objectives • Compare

    CesiumJS and MapLibre GL JS across different data formats and scales 1. Quantitative Performance Comparison • Provide clear guidance for choosing appropriate technology based on use cases 2. Establish Selection Guidelines • Develop reproducible and extensible performance evaluation methodology 3. Create Evaluation Framework
  7. 2025/11/19 FOSS4G 2025 Academic Track 9/26 Study Area: Numazu City,

    Shizuoka • Geographic Features • Area: 186.85 sq km • Population: ~188,000 • Elevation range: 0m to 1,333m • Coastline: 64.5 km on Suruga Bay • Why Numazu? • Diverse terrain (mountains, plains, coast) • Selected for Project PLATEAU (1 of 56 cities) • Rich data infrastructure
  8. 2025/11/19 FOSS4G 2025 Academic Track 10/26 Data Sources • 3D

    Building Models • Source: PLATEAU • Format: CityGML • Unit: 1 km mesh • Total size: ~2.3 GB (city-wide) • LOD: 0-2 levels • 3D Point Cloud Data • Source: VIRTUAL SHIZUOKA • Format: LAS • Unit size: 300m x 400m • Total size: ~462 GB (city-wide) • Map Info Level: 500 2nd Grid(Mesh) 10 km x 10 km area Larger scale, scalability test 3rd Grid (Mesh) 1 km x 1 km area Smaller scale, detailed analysis
  9. 2025/11/19 FOSS4G 2025 Academic Track 12/26 Data Conversion Workflows (2):

    CityGML to MVT PLATEAU GIS Converter (MIT License) Select to CityGML Output File-format Zoom-level https://github.com/Project-PLATEAU/PLATEAU-GIS-Converter File-formats 3D Tiles Mapbox Vector Tiles (MVT) GeoPackage GeoJSON Shapefile KML CZML Minecraft glTF Wavefront OBJ
  10. 2025/11/19 FOSS4G 2025 Academic Track 13/26 Five Test Configurations •

    CesiumJS • Point Cloud (3D Tiles 1.0) • Buildings (3D Tiles 1.1) • Native 3D Tiles support • Optimized for global-scale visualization • MapLibre GL JS • Point Cloud (3D Tiles 1.0) + deck.gl + loaders.gl • Buildings (3D Tiles 1.1) + deck.gl • Buildings (MVT) • Vector tile specialized • High-performance with deck.gl integration • Unified Test Environment: ・Same viewpoint (Numazu Station area) ・GSI standard map background ・Two scale levels (3rd mesh, 2nd mesh) ・2-screen comparison viewer developed
  11. 2025/11/19 FOSS4G 2025 Academic Track 15/26 Performance Evaluation Method •

    Tool: Google Chrome Lighthouse • Core Web Vitals - 5 Key Metrics FCP First Contentful Paint Time to first content display LCP Largest Contentful Paint Time to largest element display Speed Index Visual Load Progress Overall loading speed perception TBT Total Blocking Time Time page is unresponsive CLS Cumulative Layout Shift Visual stability of page layout
  12. 2025/11/19 FOSS4G 2025 Academic Track 16/26 Overall Performance Results •

    Best Overall Performance • MapLibre GL JS + MVT (Building visualization) FCP 0.8s Speed Index 0.8s TBT 0ms For Point Cloud Data MapLibre GL JS + deck.gl showed significant advantage TBT difference: greater than 20,000ms improvement For Building Models (3D Tiles) Mixed results with trade-offs MapLibre faster initial load, but higher TBT
  13. 2025/11/19 FOSS4G 2025 Academic Track 17/26 Point Cloud Data Performance

    Comparison CesiumJS (3D Tiles 1.0) MapLibre GL JS + deck.gl + loaders.gl 3rd Mesh (1km sq) FCP: 1.6s | LCP: 1.8s Speed Index: 3.3s TBT: 7,270ms CLS: 0.006 2nd Mesh (10km sq) FCP: 1.6s | LCP: 1.9s Speed Index: 3.5s TBT: 21,357ms CLS: 0.005 3rd Mesh (1km sq) FCP: 1.4s | LCP: 1.4s Speed Index: 1.4s TBT: less than 3ms CLS: 0.001 2nd Mesh (10km sq) FCP: 1.4s | LCP: 1.5s Speed Index: 1.7s TBT: less than 3ms CLS: 0.001 Key Finding: MapLibre GL JS maintained excellent responsiveness even with large-scale data, while CesiumJS showed severe blocking with over 20 second delays
  14. 2025/11/19 FOSS4G 2025 Academic Track 18/26 Building Models (3D Tiles

    1.1) Performance CesiumJS MapLibre GL JS + deck.gl 3rd Mesh (1km sq) FCP: 1.6s | LCP: 1.8s TBT: 3ms CLS: 0.006 2nd Mesh (10km sq) FCP: 1.6s | LCP: 2.0s TBT: 63ms CLS: 0.005 3rd Mesh (1km sq) FCP: 1.3s | LCP: 1.3s TBT: 1,000ms CLS: 0.001 2nd Mesh (10km sq) FCP: 1.3s | LCP: 1.3s TBT: 963ms CLS: 0.001 Interesting Trade-off: • MapLibre: Faster initial loading but higher main thread blocking • CesiumJS: Slightly slower start but better interactivity for 3D Tiles buildings • CesiumJS better optimized for native 3D Tiles 1.1 format
  15. 2025/11/19 FOSS4G 2025 Academic Track 19/26 MVT Format: Outstanding Performance

    Why MVT Excels: • Lightweight vector data format • Optimized for 2D/2.5D building visualization (LOD1) • Native support in MapLibre GL JS • Minimal processing overhead MapLibre GL JS + MVT Best-in-class performance for building visualization Consistent across both 3rd mesh and 2nd mesh scales FCP 0.8s Speed Index 0.8s TBT 0ms LCP 〜1.4s
  16. 2025/11/19 FOSS4G 2025 Academic Track 20/26 Visual Stability Analysis CesiumJS

    0.005-0.006 Good Stability Slight variations with data complexity MapLibre GL JS 0.001 Extremely Stable Consistent across all configurations ▪Key Insight: • The 5-6x difference in CLS values reflects architectural differences in 3D rendering approaches. MapLibre rendering pipeline produces more predictable and stable visual updates. ▪CLS (Cumulative Layout Shift): • Measures unexpected layout shifts during page load. Lower is better. Good: less than 0.1
  17. 2025/11/19 FOSS4G 2025 Academic Track 21/26 Key Findings Summary 1.

    Lightweight Data (MVT) Champion • MVT + MapLibre GL JS: Best overall performance (FCP 0.8s, TBT 0ms) 2. Large-Scale Point Cloud Processing • MapLibre GL JS + deck.gl significantly outperformed CesiumJS (over 20,000ms TBT difference) 3. 3D Building Models Trade-offs • CesiumJS better for 3D Tiles buildings (lower TBT), MapLibre faster initial load 4. Visual Stability • MapLibre GL JS: 5-6x more stable layout (CLS 0.001 vs 0.005-0.006) 5. Scale Dependency • CesiumJS performance degrades significantly with data volume; MapLibre more consistent
  18. 2025/11/19 FOSS4G 2025 Academic Track 22/26 Selection Guidelines by Use

    Case Use MapLibre GL JS + MVT when: Simple 3D building visualization is sufficient (LOD1) Maximum performance is critical Need heatmap or clustering features Working with 2D/2.5D data Use MapLibre GL JS + deck.gl when: Processing large-scale point cloud data Need responsive user interactions Working with massive datasets TBT optimization is priority Use CesiumJS when: High-precision 3D visualization needed Working with detailed building models (LOD2+) Need rich building attribute handling Global-scale applications
  19. 2025/11/19 FOSS4G 2025 Academic Track 23/26 Research Contributions • Framework

    applicability extends to: • WebGPU era benchmarking - 3D Tiles 1.1 evaluation - Future library development 1. Quantitative Performance Framework Lighthouse-based 5-metric evaluation methodology for 3D web mapping 2. Real-World Scale Evaluation Using actual production datasets (462GB point cloud, 2.3GB CityGML) 3. Dual-View Comparison System Custom-developed 2-screen viewer for synchronized performance analysis 4. Technology Selection Guidelines Clear, use-case-specific recommendations for library selection
  20. 2025/11/19 FOSS4G 2025 Academic Track 24/26 Conclusions • This research

    established a comprehensive performance evaluation framework for web-based 3D geospatial visualization using real-world, production-scale datasets. ✓Quantified performance differences across 5 Core Web Vitals metrics ✓Demonstrated MVT superiority for lightweight 3D building visualization ✓Revealed MapLibre advantages for large-scale point cloud processing ✓Provided clear selection guidelines based on data characteristics and requirements
  21. 2025/11/19 FOSS4G 2025 Academic Track 25/26 Future Directions • 1.

    WebGPU Era Evaluation • Re-evaluate with WebGPU technology (expected 1000% performance improvement) • 2. Next-Generation Standards • CityGML 3.0, WebXR integration, advanced LOD management • 3. Mobile Device Performance • Extend evaluation to smartphones and tablets • 4. Emerging Libraries • Evaluate new mapping engines and optimization techniques • 5. Real-World Applications • Deploy findings in production systems, measure user satisfaction
  22. 2025/11/19 FOSS4G 2025 Academic Track 26/26 Thank you ! Kia

    ora @tosseto [email protected] https://speakerdeck.com/tosseto https://tossetolab.github.io/ All source-code and results will publish by GitHub https://github.com/mapcomparejp/ ◀ Presentation Slide Available