Tile types

With the development of cache technology, SuperMap GIS products keeps on improving cache generation and cache accuracy.

In general, the map cache refers the map tiles. Starting from 7C, besides map tiles, SuperMap also provides vector tiles and attribute tiles.

Overview of three types of tile
Map tile
Vector tile
Attribute tile

Overview of three types of tile

The map caches are mainly created through Distributed Tiling service. This function enables users tiling maps into multiple types, such as FastDFS, MongoDB, SMTiles, MBTiles, UGCV5, SVTiles (vector tile), and UTFGrid (attribute tile).

UpDownType	Tile Types	Storage Mode	Storage Path	Supported Version	Supported Platform	Distributing Approach
Map Tile	FastDFS	FastDFS distributed file system	FastDFS inner distributed storage. See FastDFS Installation and Configuration, and the result is a tile set in the tile library.	Yes	Linux	Support to distribute by the export of *.smtiles
	MongoDB	MongoDB distributed file system	Data are stored in the specified path. See MongoDB Installation and Configuration, and the result is a tile set in the tile library.	No	Linux, Windows	Support to directly copy and distribute among MongoDB systems
	OTS	OTS distributed file system	Data are stored in Aliyun OTS storage service system.	No	Linux、 Windows	--
	MBTiles	SQLite database	output path\sqlite\*.mbtiles, such as China__256X256_PNG_T.mbtiles	No	Linux, Windows	Directly copy and distribute tiles
	SMTiles	SQLite database	output path\sqlite\*.mbtiles, such as China_-1085299276_256X256_PNG.smtiles	No	Linux, Windows	Directly copy and distribute tiles
	UGCV5	Stored in the local disk path	output path\cache\, see SuperMap UGC Tile Version.	No	Linux, Windows	Directly copy and distribute tiles
	GeoPackage	SQLite database	output path\sqlite\*.gpkg, such as ChinaProvinces_4326_256X256_PNG.gpkg	No	Linux, Windows	Directly copy and distribute tiles
Vector Tile	SVTiles	SQLite database	output path\sqlite\*.svtiles, such as China_1023937971_256X256.svtiles	No	Linux, Windows	Directly copy and distribute tiles
Attribute Tile	UTFGrid	SQLite database	output path\sqlite\*.utfgrid, such as China_China_Hyd_R@China400_3857_256X256_8.utfgrid	No	Linux, Windows	Directly copy and distribute tiles

Note:

Supported Platform: refers to what operating systems can store current tile format.
Supported Version: whether current tile format support tile set versioning or not.

From the table above, we can conclude that:

Tile formats that support distributed storage are: FastDFS and MongoDB. Due to the distributed advantages of reading and writing, the two formats are more suitable for the distributed tiling.
FastDFS occupies smaller disk space than MongoDB does.
MongDB is easy to use and configure. Especially, it can be deployed on Windows.
The format of SMTiles are convenient to copy and distribute; *.mbtiles can be used for offline status, so it is popular in mobile terminals

Map tile

Map tile refers to tiling maps to raster pictures. It supports FastDFS (distributed storage), MongdoDB (distributed storage), SMTiles, MBTiles, and SuperMap UGC.

SuperMap UGC type is the common and traditional type which can be used in all SuperMap products if the SuperMap UGC tile versions are the same. The UGCV5 storage format includes original type and compact type.

In addition, the picture format of the map tiles include PNG, JPG, GIF. If you choose PNG and the color value is less than 256, pictures will auto stored as PNG8 in SuperMap iServer for saving more storage space.

Vector tile

The vector layer can be splitted and stored as the vector tiles. iServer supports SVTiles.

In the real map service field, users not only view maps, but also query, select or highlight elements on maps. So, element service becomes a necessity. Similar to the improvement of map tile access, the rendering of elements on the client side can be improved by pre-caching vector data. Here comes the vector tile technology. The storage space of vector data is smaller than map tiles, so it is more suitable for expressing geospatial elements which requires timeliness, such as POI, routes, etc. The popular online map services, such as Google Maps, Baidu Map, use map tiles as the base map and vector tiles as element service.

Attribute tile

The attribute data in the vector layers can be stored as the attribute tiles. iServer supports UTFGrid.

In the real map service field, if there are massive mouse interactive operations, in the traditional way, we will overlay the element layers on the maps, and every element has its own hot spot and event. However, in the environment of massive amount of data and high concurrent requests, the clients, especially the mobile terminal, cannot smoothly render so many geographic elements. In this case, we choose another way, that is, every tile also records the attribute information. In other words, we input attribution information, divided by grids, of elements into the original tiles. This pre-stored element attribute information for each tile is so-called attribute tile. The integration of map tiles and attribute tiles has been widely used in many sectors. The most typical one is MBTiles specification and its subsidiary UTFGrid specification.