Vector tiles are a very effective vector data format for web mapping. The principle consists of dividing all of the vector data of a project into tiles, in a manner analogous to raster data tiles (WMTS).

There are several standards for producing vector tiles. Mapbox proposed a standard based on the Protocol buffers ("Protobuf") encoding created by Google (https://developers.google.com/protocol-buffers). Mapbox vector tiles (mvt) are supported by a wide range of mapping products including JMap Cloud, JMap Server and JMap NG.

A grid that defines the tiling is applied to the vector data which is then cut into tiles. Each tile can contain vector data from multiple layers.

A set of tiles is produced for each scale level. In web cartography in general, 23 scale levels are considered, level 0 corresponding to the Earth and level 22 corresponding to the street. The vectors of the lower levels are simplified (generalized) to optimize the display of data while keeping tiles of an efficient volume.

The vectors (lines, polygons) of each layer are cut at the tile boundaries. When geometries cross the border between tiles, the tiles are cut and each tile contains part of the geometry. It is the mapping application that unifies the vectors to obtain the complete geometry.

Attributes of map elements are included in the tiles. This makes the data more dynamic and interactive, allowing for example to display thematics created on the fly or to display data based on the application of filters based on their attributes.

The vector tiles therefore contain the geometries and their attributes, the 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 because the applications manage the styles. Additionally, when the data style changes it is not necessary to generate new tiles.

The tiles can be created in advance and cached, the server response being much faster to requests from the web mapping application, which gives a very fluid and efficient rendering.

Production of vector tiles by JMap Cloud

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

• A JSON file containing style. This file accompanies the vector tiles. It contains the definition of each layer contained in the vector tiles, their style settings, themes, etc.

• A set of vector tiles that contain the geometries and attributes of non-editable layers. JMap produces one mvt format file per tile. These tiles can be created on demand as users navigate JMap NG applications. They can also be created in advance and cached.

• Vector data in GeoJSON that corresponds to the geometries and attributes of the editable layers. This data is sent on-demand by region to apps.

Factors that affect the performance of vector tiles

In general vector tiles are lighter than raster tiles but certain factors can affect the size of the tiles and have an impact on the performance of JMap NG applications. The size of the tiles is associated with the time of their production, the storage volume, the volume of data exchanged with the applications and the dedicated memory of the applications.

Among the factors to consider we can cite:

• Number of attributes linked to layers: Attribute data influences the size of the tiles, which increases with the number of attributes.

• Layer visibility scales: Setting visibility thresholds for layer display is appropriate when layers have very dense data. Limiting the display of these layers to larger scales is a good strategy because tiles at smaller scales will not contain data from these layers and tile production time will be reduced.

• Caching: Producing and caching tiles in advance greatly improves application performance.

Managing the project's MVT cache

Pour gérer le cache de tuiles vectorielles du projet :

To manage the project's vector tile cache: Press to access functions. Tap MVT Cache to open the Manage MVT Tile Cache interface of the project. This interface has four sections:

2. Indicate the task you want to perform.

3. Click on Launch task. The Running task section displays task progress graphically and in percentage..

Projects that you have created (and of which you are then the owner) as well as projects for which you have access permissions appear in the Projects section.

Two display modes are available in this section: table mode, similar to the display mode of other JMap Cloud Portal resources, or card mode. You can switch between modes by pressing the and icons respectively.

When projects are displayed in list mode you can sort and filter them based on their name or modification date.

The Menu available in both display modes offers functions for managing each project: , , , , , . The following sections describe these functions in detail.

You can delete a project for which you have Owner permission. Deleting the project deletes the project's map layers as well as these configurations.

To delete a project:

1. Click on and then on Delete. A message asks you to validate your choice.

The project disappears from the Projects section.

To open the project to explore it and fine-tune the configuration before making it available to users:

1. Click on and then on Open. A JMap NG application displaying the project opens in a new tab.

2. Log in to the application with your JMap Cloud Portal login information.

3. Navigate the map and explore the app. The functions offered by JMap NG are available (see details in the JMap NG User Guide). It is the cartographic application that broadcasts the project to members whose role is Viewer.

4. In JMap NG, click on and then Logout to close the application.

To change project settings:

1. Click on and then on Edit.

2. Edit the project settings. You can change all settings.

3. Click on Edit to save the changes. The date of the modification is displayed in the Modification column (in the list view mode).

You can grant permissions to other JMap Cloud members in your organization for projects that you own.

Three permissions are offered. The permissions are hierarchical, in the sense that the broadest permission includes the other two permissions.

Granting permissions

To grant permissions to a project:

1. Click on and then on Permissions. The permissions configuration interface opens displaying the members with the permissions each has.

2. To grant permissions to a member, open the Add member drop-down list.

3. Select the member you are interested in. Their name along with a letter that indicates their role appears in the Add member field. You can clear the selection by clicking .

4. Select the other members you want to add, one at a time. Their names appear in the Add member field. You can clear the selection by pressing .

5. Once members are selected, click on to add the members. These are displayed in the permissions table.

6. Check the permissions you want to grant to each member. The Owner permission automatically includes the other two permissions.

Modifying permissions

You can modify the permissions granted to members, grant permissions to new members, or remove all permissions from one or more members.

2. Change the permissions by checking or unchecking the relevant boxes. To remove all permissions from a member, you must uncheck all three permissions. When you uncheck the Owner permission box, Modify automatically becomes the most important permission.

When the visibility of a project is Public, users access the project without the need for authentication. When visibility is Private, users must have at least View permission to access the project.

To obtain the sharing link to share a Public project:

1. Click on and then on Get project's public link. This function is inactive for projects with Private visibility type.

You can copy this link also from the project configuration interface. This is relevant when you make a project Public:

1. Click on and then on Edit to open the project configuration interface.

2. If you have Owner permission, check the Public box to make the project public. The icon appears next to the box.

3. Click on to copy the project share link to the clipboard.