The Maps SDK uses JSON file (styles) defining the sources of data to be shown on the map and its appearance. Styles are compliant with the Map Styles Specification .
layers property of a style is an array of all the layers the style defines. Each element of
the array contains all the information needed to render a layer. Note that a single element of a
map, such as a road, may consist of several layers. Among the properties of a layer, two are of
particular interest in this context:
source- The name of the source of data for the layer corresponds to a child of the
source-layer- The name of a layer in a vector tile source; corresponds to an element of a vector tile.
Sources are defined as properties of the
sources root property of a style. The structure of a
source depends on its type. The style used in the Maps SDK contains three types of source:
vector- vector map and traffic tiles
raster- raster map and traffic tiles
geojson- additional elements such as chevron, gps inaccuracy radius indicator, etc.
source layer property of a layer is mandatory for all layers of the
vector type. It defines
the element of a vector tile (also called a layer) which is the source of data for this layer.
As noted in the #layersLayers section, there are elements of the map that consist of multiple layers. The layers that constitute such an element might refer to the same source layer. For instance - the visual representation of a minor local toll road comprises 11 layers - one for the main part, one for the outline, another one for a road that goes through a tunnel, etc.
Check the Map Display API documentation for a complete list of vector layer sources (layers in a vector tile) used in the SDK.