Architectures of Tiled Map Services
Since it had the mosaic tile-like map data and the similar functionality of SVGMap, we evaluated Tile_Map_Service_Specification(TMS).
It seems that the differences between two specifications are as follows.
| SVG Map | TMS | |
| Basic concept | Versatility and generality are considered as important by extending the minimum metadata and logic to the basic specifications of general-purpose SVG. | A build of a simplistic map services is considered as important with the hardcode like specifications in which TiledMapServices specialized using. |
| Projection | From an compatibility with original SVG, only the projection by the primary affine transformation is supported. |
Some well known projections by which the preset was carried out as specifications can be used. |
| Data formats for tiling functionality | The single data format by which few metadatas for a map were embedded at the general-purpose data format (SVG). | Three data formats for a map services prepared for each functionality |
| Storage structure of tiles | All of the filename and directory-name of a tile, and directory structure can be set up freely. | The preset (hard code) of directory structure and the filename is carried out as specifications. |
| Splitting structure of tiles | The splitting for a non-equality, a random splitting, a splitting with a gap which were optimized based on the density of a data are possible. Instead, a layout of a tile must be specified by an index data (container SVG). | Only a splitting of the division into equal parts by which the preset was carried out as specifications is supported. Where, splitting size can be set up freely. Instead, an index data is compact. |
| Supported graphics type | Vector(SVG) and Raster(JPEG,PNG) | Raster? |
It seems that those differences are caused by whether it was designed based on GIS, or general-purpose Web contents. We will choose fusion generative architectures, since we aim at Web which the geospatial map fused with various contents.
Note: NASA's OnEarth has tried the delivery of the hint information for obtaining a tiled map efficiently based on WMS. However, this looks like the extemporaneous (stop-gap) extended specifications of WMS.
