Publication Date: 2020-07-08
Approval Date: 2020-06-26
Submission Date: 2020-05-05
Reference number of this document: OGC 19-084
Reference URL for this document: http://www.opengis.net/doc/PER/vtp2-D002
Category: OGC Public Engineering Report
Editor: Andrea Aime
Title: OGC Vector Tiles Pilot 2: Vector Tiles Filtering Language Engineering Report
Copyright © 2020 Open Geospatial Consortium. To obtain additional rights of use, visit http://www.opengeospatial.org/
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- 1. Subject
- 2. Executive Summary
- 3. References
- 4. Terms and definitions
- 5. Overview
- 6. Introduction
- 7. Previous work
- 8. Filter Conceptual Model and VTP2 testing considerations
- 9. Filtering Tiles
- 10. Filtering GeoPackages with Vector Tiles
- 11. Implementations
- 11.1. GeoSolutions D100 OGC API - Features
- 11.2. Terranodo D100 OGC API - Tiles
- 11.3. interactive instruments D101 Features, Tiles and Styles API
- 11.4. GeoSolutions D102 OGC API - Tiles
- 11.5. Ecere D103 Features & OGC API - Tiles
- 11.5.1. Examples of filtering expressions used with the OGC API - Features
- 11.5.2. Use of filtering for vector tiles
- 11.5.3. Multi-layer and scale-based filtering (OGC API - Tiles)
- 11.5.4. POST requests to the OGC API - Tiles
- 11.5.5. Filtering driven by styles
- 11.5.6. Retrieving attributes separately from geometry
- 11.5.7. CMSS Expressions Syntax
- 11.6. Ecere D105 Client
- 11.7. Ecere D107 GeoPackage producer & client
- 11.8. Skymantics D104 Client
- 11.9. GeoSolutions D104 Client
- 12. Results and findings
- 12.1. Issues Encountered
- 12.2. Findings
- 12.3. Recommendations
- 12.4. Future work
- Appendix A: CQL BNF
- Appendix B: Queryables
- Appendix C: Filter capabilities
- Appendix D: Revision History
- Appendix E: Bibliography
The OGC Vector Tiles Pilot 2: Vector Tiles Filtering Language Engineering Report (ER) defines a filter language for vector data delivered as tiles (also known as vector tiles). The language applies to vector tiles served through implementations of the OGC API – Features standard and the draft OGC API - Tiles specification, but can be generally applied on all services supporting filtering by attributes.
The ER further includes an assessment of filter languages, styles and online/offline symbol sharing for GeoPackages, OGC API - Features and OGC API - Tiles implementations for accuracy and completeness in applications that render vector tiles at local to regional scales.
1.1. Target Scenario
The main benefits for transitioning from raster tiles to vector tiles has been the possibility of flexible map styling and the reduction of storage space required for maps, the latter allowing for maps being stored on devices with lower storage capacity as well as requiring lower bandwidth communications for transmission. In some cases, maps represented with vector tiles can be 20 to 30 times smaller than the same maps represented by raster tiles. This reduction enables the possibility of storing large sets of maps (i.e.,tile sets) into secure and lightweight removable media devices.
As described in Figure 1, a tile set repository (such as GeoPackage, Static Cache, or Compact Cache V2) is being used by a humanitarian relief convoy in the middle of the desert and with limited to no connectivity, supported by a group of interconnected systems working and communicating with each other. The repositories are generated at Command Post Computing Environments (CPCE) and comprise tile sets, styles, maps and routes served by National-level Services and Enterprise-level Services, which communicate with each other throughout OGC API Styles, API Tiles, API Images and API Routes.