A method for generating a raster map for navigation or positioning, the method comprising: generating a first raster map having a first resolution based on an acquired laser point cloud; generating a second raster map having a second resolution by merging rasters in the first raster map, the second resolution being lower than the first resolution; and storing the first raster map and an association between the first raster map and the second raster map; characterized in that the method further comprises: acquiring an updated laser point cloud; registering the updated laser point cloud with the laser point cloud by adjusting a coordinate system of the updated laser point cloud based on the coordinate system of the laser point cloud; and updating the first raster map using the registered updated laser point cloud; wherein the method further comprises invoking the first raster map during the navigation or positioning, comprising: receiving a request for a digital map; in response to determining that the request relates to the first raster map, obtaining the first raster map; and in response to determining that the request relates to the second raster map, obtaining the first raster map and the association between the first raster map and the second raster map; and dynamically generating the second raster map based on the stored first raster map and the stored association between the first raster map and the second raster map. generating a first raster map having a first resolution based on an acquired laser point cloud; generating a second raster map having a second resolution by merging rasters in the first raster map, the second resolution being lower than the first resolution; and storing the first raster map and an association between the first raster map and the second raster map; characterized in that the method further comprises: acquiring an updated laser point cloud; registering the updated laser point cloud with the laser point cloud by adjusting a coordinate system of the updated laser point cloud based on the coordinate system of the laser point cloud; and updating the first raster map using the registered updated laser point cloud; wherein the method further comprises invoking the first raster map during the navigation or positioning, comprising: receiving a request for a digital map; in response to determining that the request relates to the first raster map, obtaining the first raster map; and in response to determining that the request relates to the second raster map, obtaining the first raster map and the association between the first raster map and the second raster map; and dynamically generating the second raster map based on the stored first raster map and the stored association between the first raster map and the second raster map. acquiring an updated laser point cloud; registering the updated laser point cloud with the laser point cloud by adjusting a coordinate system of the updated laser point cloud based on the coordinate system of the laser point cloud; and updating the first raster map using the registered updated laser point cloud; wherein the method further comprises invoking the first raster map during the navigation or positioning, comprising: receiving a request for a digital map; in response to determining that the request relates to the first raster map, obtaining the first raster map; and in response to determining that the request relates to the second raster map, obtaining the first raster map and the association between the first raster map and the second raster map; and dynamically generating the second raster map based on the stored first raster map and the stored association between the first raster map and the second raster map. receiving a request for a digital map; in response to determining that the request relates to the first raster map, obtaining the first raster map; and in response to determining that the request relates to the second raster map, obtaining the first raster map and the association between the first raster map and the second raster map; and dynamically generating the second raster map based on the stored first raster map and the stored association between the first raster map and the second raster map.