LogoLogo
English
English
  • Welcome to JMap Server Kathmandu
  • Administrator
    • JMap Server Administrator Manual
      • Introduction
        • Quick Start Guide
        • User Interface
      • Databases
        • System Database
        • Creating Databases
        • Configuring and Managing Databases
        • SQL Console
      • JMap Server to JMap Server Connections
        • Creating Connections to JMap Server
        • Configuring JMap Server to JMap Server connections
          • Permissions for the remote connection
        • Managing connections
      • Spatial Data Sources
        • Creating Spatial Data Sources
        • Configuring Spatial Data Sources
          • Spatial Data Source Permissions
          • External Attributes
          • Metadata
        • Sharing Spatial Data Sources
        • Vector Data Sources
          • JMap ADF - E00 Arc - Info reader
          • JMap CSV reader
          • JMap DGN V7 - V8 File reader
          • JMap DWG - DXF reader
          • JMap EDIGEO reader
          • JMap File geodatabase reader
          • JMap GeoJSON reader
          • JMap GML reader
          • JMap GPX reader
          • JMap IFC reader
          • JMap KML reader
          • JMap MID - MIF reader
          • JMap Photo reader
          • JMap SHP reader
          • JMap TAB reader
          • Annotations in a database
          • ArcGIS REST
          • ArcSDE geodatabase
          • Coordinates in a database
          • Enterprise geodatabase
          • JMap Server
          • JMap Spatial Table
          • MongoDB
          • MySQL Spatial
          • OGC API Features
          • Oracle Spatial Locator
          • Personal geodatabase
          • PostGIS
          • SQL Server Spatial
          • WFS Server
          • WKB or WKT in a database
        • Raster Data Sources
          • ECW - JPG2000
          • GDAL - Geospatial Data Abstraction Library
          • ArcGIS REST
          • JMap Server
          • OpenStreetMap
          • WMS server
          • WMTS Server
      • Projects
        • Creating Projects
          • Vector tiles in JMap
          • Multilingual Projects
        • Configuring Projects
          • Project Permissions
          • Organizing Layers
          • Attribute Queries
            • Attribute Query Forms
          • Personal Layers
        • Managing Projects
        • Style Templates
      • Layers
        • Managing layers in a project
        • Creating Layers
        • Configuring Layers
          • General Settings
          • Layer Permissions
          • Dynamic Filters
          • Style
          • Thematics
          • Labels
          • Mouseover
          • Information Reports
          • Forms
            • Layer Attributes Forms
            • Database Forms
        • JMap extensions
        • Sharing Layers
      • JMap Server Applications
        • Classical applications
          • JMap Pro Applications
          • JMap Web Applications
            • Using a GeoWebCache Server
          • WFS and WMS Services
        • New generation applications
      • JMap Server Extensions
      • Security
        • Managing Users
          • JMap DB user manager
          • Composite user manager
          • Active Directory user manager
          • JMap LDAP user manager
          • OpenID Connect (OIDC) user manager
          • SAML2 user manager
        • Managing User Accounts and Groups
          • Single Sign-On for JMap Pro
        • Managing Permissions
        • Managing Sessions
        • Using HTTPS with JMap
      • JMap Server Management
        • JMap Server Status
        • Exporting and Importing
        • User Data
        • JMap Server Settings
        • Usage Statistics
        • Log Files
        • Messages
        • JMap Server System Database
        • Backups
      • Advanced Features: Debugging Tools
    • Technical Specifications
    • Installation Guide
    • Installing and Starting JMap (with installer)
    • Installing and Starting JMap (in a Docker container)
    • Migration Guide to JMap Server Kathmandu
  • Applications User
    • JMap Server Applications
    • JMap Pro User Guide
      • Introduction
        • User Interface
        • Navigating on the Map
        • Map Management
        • Map Settings
      • Map Layers
        • Layer Management
        • Elements Explorer
        • Thematic Maps
        • Layer Metadata
        • Layer Settings
          • General
          • Style
          • Thematics
          • Labeling
          • Mouseover
          • Filters
          • Advanced
        • Editable Layers
          • Editing Data
          • Personal Layers
      • Tools
        • Labeling
        • Interactive Selection
        • Information Tools
          • Information Report
          • Geometry Information
          • Mouseover
        • Snap
        • Measurement
        • Search Tools
          • Attribute Queries
          • Spatial Queries
        • Collaboration Tools
          • Map Contexts
          • Sharing Maps
          • Printing Maps
      • Application Settings
      • Keyboard and Mouse Shortcuts
    • JMap NG User Guide
      • Introduction
        • Connecting to JMap NG
        • User Interface
        • Navigating on the Map
        • Profile and User Settings
      • The Data
        • The Layers Panel
        • Data Layers
          • Displaying Layers
          • Thematics
          • Layer Information
          • Geographic Extent of the Layer
          • Filter Elements on the Map
          • Making Layer Elements Selectable
      • I Wish to...
        • Display Element Information
          • Tooltips
          • Information Reports
        • Perform Searches
        • Select Elements on the Map
        • Measure Distances and Surfaces
        • Add Annotations to the Map
        • Edit Data
        • Create and Manage Customized Maps
        • Export / Print a Map
    • JMap Survey User Guide
      • Introduction
        • Working With an iOS Device
        • Working With an Android Device
        • Logging In
        • User Interface
      • The Data
      • I Wish to...
        • Access Information Associated With an Object
        • Perform Searches
        • Create Objects
        • Modify Objects
        • Work in Offline Mode
        • Synchronize Data with JMap Server
        • Log Out
    • JMap Web User Guide
  • JMap Server Extensions
    • Edition
      • JMap Edition User Guide
        • User Interface
        • Basic Concepts
        • I Wish to...
          • Edit Layers Geometries
            • Edition Tools
            • Selecting Elements
            • Node and Polygon Operations
            • Vertical Position and Element Duplication
            • WKT Geometries
          • Perform Spatial Operations
            • Geoprocessing
            • Spatial Tools
    • Export
      • JMap Export User Guide
    • Import
      • JMap Import User Guide
        • Importation Procedure
          • Importing MIF Files
          • Importing SHP Files
          • Importing CSV Files
          • Importing NMEA Data
          • Importing Data From WMS
    • Tracking
      • Administrator
      • User
    • Documents
      • Documents 7
      • JMap Documents User Guide
        • Configuring JMap Documents
          • Selecting the data sources to which documents can be associated
          • Configuring document depots
          • Managing depots
          • Making the extension available in apps
        • Documents for JMap Pro
          • Graphical interface
          • Associating documents with map elements
          • Searching for documents
          • Displaying the list of documents associated with elements
        • Documents for JMap NG
          • Graphical interface
          • Searching documents
          • Showing selected documents
        • Documents for JMap Survey
  • Developer
    • JMap Server REST API
    • JMap Admin REST API
    • JMap Pro / Server API
    • JMap Web API
    • Developer Manual
    • JMap NG Developer Manual
  • Knowledge Base
    • Knowledge Base
Propulsé par GitBook

K2 Geospatial 2022

Sur cette page
Exporter en PDF
  1. Administrator
  2. JMap Server Administrator Manual
  3. Projects
  4. Creating Projects

Vector tiles in JMap

PrécédentCreating ProjectsSuivantMultilingual Projects

Dernière mise à jour il y a 2 ans

Vector tiles are a format of vector data that is very effective for web-based mapping. With vector tiles, the entire vector data of a project is divided into tiles, similarly to raster data tiles (WMTS).

There are several standards for creating vector tiles. Mapbox has provided a standard based on the protocol buffer encoding (“Protobuf”) created by Google (). Mapbox vector tiles (mvt) are supported by a wide range of map-based products, including JMap 7 as of the Jakarta version.

A grid defining the tiling is applied to the vector data, which is split into tiles. Each tile can contain the vector data (vectors) of several layers.

A set of tiles is produced for each scale level. Generally, there are 23 scale levels in web-based mapping, 0 being Earth level and 22 being street level. The vectors of lower levels are simplified (generalized) to optimize the display of the data, while maintaining a volume of tiles that performs well.

The vectors (lines, polygons) of each layer are clipped at the boundaries of the tiles. When a geometry crosses over the boundary between tiles, it is cut, and each tile thus contains part of the geometry. The map application reunites the vectors to obtain the full geometry.

The attributes of map elements are included in the tiles. This makes it possible to display thematics created on the fly or to display data in a map using attribute filters, for instance. This makes the data more dynamic and interactive.

The vector tiles contain the geometries and their attributes; styles are not included in the tiles. The information defining the styles is stored and managed in a separate JSON file. This feature allows application users to define styles dynamically, since the applications manage the styles. In addition, when the style of the data changes, it is not necessary to generate new tiles.

Tiles can be created in advance and cached; the server responds much more quickly to queries from the web-based mapping application, and therefore the rendering of the map is very smooth and performs well. In addition, the tiles can be used with for smooth and efficient rendering, especially in 3D.

Producing vector tiles with JMap

A JMap project generates three sets of data that are used by the applications:

  • 1 JSON style file. This file accompanies the vector tiles. It contains the definition of each layer contained in the vector tiles, their style parameters, the thematics, etc.

  • A set of vector tiles containing the geometries and attributes of non-editable layers. JMap produces an MVT file for each tile. These tiles can be created on request when users navigate through the JMap Survey or JMap NG applications. They can also be created in advance and cached. The following offers details on how to create and manage the cache of tiles with JMap.

  • GeoJSON vector data corresponding to the geometries and attributes of editable layers. This data is sent to applications on request, by region.

Regardless of the procedure used to create tiles (on request or in advance with caching), the tiles are created in the cache/mapbox directory of JMap Server. In this directory, there is one folder per project (named using the project ID), which contains one folder per resolution (currently 512). The files of the tiles are named using the z-x-y.mvt code, where z is the scale level, and x and y indicate the position of the tile in the grid.

Factors affecting the performance of vector tiles

In general, vector tiles are lighter than raster tiles, but some factors can affect the size of tiles and impact the performance of the JMap Survey and JMap NG applications. The size of tiles is associated with the time it takes to produce them, their storage volume, the volume of data exchanged with the applications, and the dedicated memory of the applications.

Some factors to consider:

  • Number of attributes bound to layers: the attribute data influences the size of the tiles; the more attributes there are, the more the size increases.

  • Layer visibility scales: Establishing visibility thresholds for the display of layers is recommended when layers have very dense data. A good strategy is to limit the display of these layers to larger scales because the tiles of the smaller scales will not contain the data of these layers, and the time required to produce the tiles will be reduced.

  • Caching: producing tiles in advance and caching them greatly improves application performance, while reducing JMap Server’s workload. JMap Server can indeed reach its full workload capacity when several users are navigating through large and complex projects in the applications.

  • JMap server memory: influences the performance of tile production. Increasing the memory allocated to the JMap server can accelerate tile production.

https://developers.google.com/protocol-buffers
WebGL
article
img