Tile scheme

All mapx tiles follow the common web map scheme. With MapLibre, Leaflet, OpenLayers or QGIS you do not need to configure anything; for your own requests and calculations, here is what matters.

Projection and address

The world is projected in Web Mercator (EPSG:3857) onto a square and divided into zoom levels. At level z the square has 2^z × 2^z tiles. A tile is addressed as z/x/y: x counts from west to east, y from north to south (XYZ scheme, not TMS), both starting at 0.

Tile for a point lon, lat (degrees) at level z:

function tile(lon, lat, z) {
  const n = 2 ** z;
  const x = Math.floor(((lon + 180) / 360) * n);
  const r = (lat * Math.PI) / 180;
  const y = Math.floor(((1 - Math.log(Math.tan(r) + 1 / Math.cos(r)) / Math.PI) / 2) * n);
  return { z, x, y };
}
tile(12.694, 47.074, 12);   // { z: 12, x: 2192, y: 1439 }

A tile is served by https://tiles.mapx.at/v1/tiles/{tileset}/{z}/{x}/{y}.{ext}, see Tiles.

512-pixel tiles

mapx raster tiles (elevation models, orthophoto) are 512 × 512 pixels, not 256. A 512 tile covers the same area as four 256 tiles one level deeper. Clients need the right setting:

• MapLibre: tileSize: 512 (automatic with TileJSON).
• Leaflet: tileSize: 512, zoomOffset: -1.
• OpenLayers: tileSize: 512 on the source.
• QGIS: tile resolution 512.

If you forget it, the map looks off by one zoom level and blurry or too fine.

Resolution per zoom level

Resolution depends on latitude. The table applies to 47.5° N, the middle of Austria:

One level deeper halves the pixel size. The elevation models exist up to z16, the orthophoto up to z18.

Overzoom

If a level is higher than the stored one, the client scales up the tiles of the highest level (overzoom). The image does not get sharper, but the map stays usable. In MapLibre set maxzoom of the source to the highest existing level (automatic from TileJSON); the map itself may zoom further. Requests outside the zoom range return 404, see Errors and limits.

Further reading

• Elevation values in tiles: Terrain-RGB.
• Coordinates and projections: Coordinates.