Shaded relief WebMercator 'slippy map' tiles based on NASA Shuttle Radar Topography Mission Global 1 arc second V003 topographic height data

This dataset contains WebMercator tiles which contain gray-scale shaded relief (hill shades), and nothing else. The tiles have a resolution of 256×256px, suitable for web mapping libraries such as Leaflet. The hill shades are generated from SRTM altitude data, which cover the land area between 60° northern and 58° southern latitude, and which lies in the public domain. Map material without political or infrastructural features can be desirable, for example, in use cases where historical data is visualized on a map. The concrete motivation for generating this map material was the Dhimmis & Muslims project (project page, home page, GitHub, DaRUS dataset), which analyzed peaceful coexistence of religious groups in the medieval Middle East. A particular goal with creating the dataset was to have map material available under a permissive license for screenshots and publications, instead of relying on proprietary mapping services such as Mapbox. Teaser image: The hillshades of Cyprus on zoom level 9. This image is hosted externally by GitHub, but is also present in the repository as teaser.png. Coverage. The dataset covers zoom level 0 (entire world in one tile) to 12 (entire world in 4096×4096 tiles). The total size of the dataset is 22,369,621 tiles. However, of those, 19,753,304 tiles (88.3%) are empty, either because the landscape there is fully flat (i.e., on water), or because they lie fully outside the latitude range covered by the SRTM altitude data. The empty tiles are not stored. Instead, a singular placeholder file is stored in the repository, alongside a list of the empty tiles. During extraction, the placeholder empty tile can be symbolically linked in the file system to all the places where it is needed. The total size of the non-empty tiles is about 103GB. Files. Besides the placeholder file and the list of empty tiles, the repository also contains a manifest file. This file lists all non-empty tiles by the ZIP file they are contained in. The tiles themselves are grouped into ZIP files by the following schema: All tiles from levels 0 to 5 are contained in one ZIP file. All tiles of level N, N≥6 are contained in a ZIP file which is named after the tile of level N-6 (block level) that contains the tile in question, named tiles______.zip. Hence, all tiles of level 6 are contained in a singular ZIP file named tiles__6__0_0_0.zip. The tiles of level 7 are split up into four group ZIP files named tiles__7__1_{0,1}_{0,1}.zip, the tiles of level 8 into 16 group ZIP files named tiles__8__2_{0..3}_{0..3}.zip, and so on. Both the manifest file and the commands to generate the distribution of tiles on ZIP files can be generated using the linked software repository. Usage. The tile ZIP files can be downloaded and extracted. By serving the extracted directory structure in a web server, a slippy map tile server can be created. The linked software repository also contains a command-line utility that generates the required shell commands to download the ZIP files, extract them, and softlink (ln -s) the empty tiles to the appropriate places. This command-line utility can also optionally read in a GeoJSON file of an area of interest. In this case, only tiles within that area are downloaded in a higher zoom level, whereas tiles completely outside the area are only downloaded to a lower zoom level; both zoom levels are also configurable. See the documentation in the repository and the command-line utility’s help (-h) output for more details.

本数据集仅包含Web墨卡托（WebMercator）瓦片，且仅存储灰度晕渲山体阴影图（hill shades），无其他内容。
该瓦片分辨率为256×256像素，适配Leaflet等主流Web地图库。
本数据集的山体阴影图源自SRTM高程数据，该数据覆盖北纬60°至南纬58°之间的陆地区域，且已进入公有领域。
无政治或基础设施标注的地图素材在诸多场景中具备应用价值，例如历史数据的地图可视化场景。
本地图素材的开发初衷源于Dhimmis & Muslims项目（项目页面、主页、GitHub仓库、DaRUS数据集），该项目旨在探究中世纪中东地区不同宗教群体的和平共处状况。
构建本数据集的核心目标之一，是获取可在宽松许可协议下用于截图与出版物的地图素材，无需依赖Mapbox等专有地图服务。
预览图：塞浦路斯地区9级缩放下的山体阴影图。该图片由GitHub外部托管，同时也以teaser.png的名称存储于本仓库中。
覆盖范围：本数据集支持0级（单瓦片展示全球）至12级（4096×4096瓦片展示全球）的缩放级别。
数据集总瓦片数为22,369,621张，但其中19,753,304张（占比88.3%）为空瓦片：这些空瓦片要么对应完全平坦的地表（即水域），要么完全处于SRTM高程数据覆盖的纬度范围之外。
空瓦片并不会被实际存储。仓库中仅存储单个空瓦片占位文件，以及空瓦片清单。在解压阶段，可通过文件系统符号链接将占位文件映射至所有需要空瓦片的位置。
非空瓦片的总存储容量约为103GB。
文件结构：除占位文件与空瓦片清单外，本仓库还包含清单文件（manifest file）。该文件按照ZIP压缩包的归属关系，列出所有非空瓦片。
瓦片分组规则：所有瓦片按照以下规则存入ZIP压缩包：0至5级的所有瓦片统一存储于单个ZIP文件中。
对于N≥6的第N级瓦片，其所属ZIP文件以覆盖该瓦片的N-6级（区块层级）瓦片命名，命名格式为tiles______.zip。
因此，第6级的所有瓦片均存储于单个名为tiles__6__0_0_0.zip的ZIP文件中。
第7级瓦片被分为4个分组ZIP文件，命名格式为tiles__7__1_{0,1}_{0,1}.zip；第8级瓦片则分为16个分组ZIP文件，命名格式为tiles__8__2_{0..3}_{0..3}.zip，以此类推。
清单文件以及瓦片分组至ZIP文件的生成脚本，均可通过关联的软件仓库生成。
使用方式：可下载并解压瓦片ZIP文件。将解压后的目录结构部署至Web服务器中，即可搭建交互式滑动地图瓦片服务器。
关联的软件仓库还提供了命令行工具，可生成所需的Shell脚本命令，用于下载ZIP文件、解压文件，并通过软链接（ln -s）将空瓦片映射至对应位置。
该命令行工具还支持可选读取目标区域的GeoJSON文件。
在此模式下，仅下载目标区域内的高缩放级别瓦片，而完全处于区域外的瓦片仅需下载至低缩放级别；缩放级别均可自定义配置。
更多细节请参阅仓库中的文档，以及命令行工具的帮助（-h）输出信息。