android - 什么是 map 瓦片？

Question

我阅读了 google android api 并且对 map 图 block 是什么感到困惑，因为该 api 描述了 google map 如何处理“下载 map 图 block ”。(来源)- https://developers.google.com/maps/documentation/android/map .谁能快速概述一下什么是 map 图 block 。只是适合设备屏幕的 map 部分？

Answer 1

在设备屏幕上呈现的 map 部分可以由许多图 block 组成。基本上， map 根据缩放级别被分割成多个图 block 。

来自 OpenStreetMap-Wiki :

square bitmap graphics displayed in a grid arrangement to show a map.

来自 Google Maps Android API :

The Google Maps API breaks up the imagery at each zoom level into a set of square map tiles arranged in a grid. When a map moves to a new location, or to a new zoom level, the Maps API determines which tiles are needed and translates that information into a set of tiles to retrieve.

The tile with coordinates (0,0) is always at the northwest corner of the map, with x values increasing from west to east and y values increasing from north to south. Tiles are indexed using x,y coordinates from that origin.

At zoom level 0, the entire world is rendered in a single tile. Each zoom level increases the magnification by a factor of two. So, at zoom level 1 the map will be rendered as a 2x2 grid of tiles. At zoom level 2, it's a 4x4 grid. At zoom level 3, it's an 8x8 grid, and so on.

Bing Maps Tile System :