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README.md

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+---
+license: other
+task_categories:
+  - other
+tags:
+  - elevation
+  - srtm
+  - geotiff
+  - dem
+  - terrain
+size_categories:
+  - extra-extra-large-1M+
+---
+
+# SRTM 30m Global Digital Elevation Model
+
+NASA Shuttle Radar Topography Mission (SRTM) 30m resolution global DEM, converted to Cloud Optimized GeoTIFF format.
+
+## Dataset Details
+
+- **Source:** NASA SRTM GL1 v3 (Global 1 arc-second, ~30m resolution)
+- **Coverage:** 80% of land surface between 56°S and 60°N
+- **Resolution:** ~30 meters (1 arc-second)
+- **Format:** GeoTIFF with Deflate compression, 16-bit signed integer
+- **Files:** 14,296 tiles, ~65 GB total
+- **Tile naming:** `N{lat}E{lon}.tif` or `S{lat}W{lon}.tif` (1°×1° tiles)
+- **Internal tiling:** 256×256 pixels, 15×15 grid per file (225 internal tiles)
+- **NoData value:** -32768
+- **Horizontal datum:** WGS 84
+
+## Usage
+
+### Via OpenZenith API
+
+```
+GET https://openzenith.pages.dev/api/elevation?lat=28.5&lon=96.5
+```
+
+### Direct download
+
+```python
+from huggingface_hub import hf_hub_download
+path = hf_hub_download("aliasfox/srtm30m", "N28E096.tif", repo_type="dataset")
+```
+
+### HTTP Range requests
+
+Each GeoTIFF file supports HTTP Range requests. The first ~4KB contains the IFD (Image File Directory) with tile offsets. Each 256×256 internal tile can be fetched individually (~3-53 KB compressed).
+
+## File Structure
+
+Each file covers a 1°×1° area:
+- Image size: 3601×3601 pixels
+- Pixel values: elevation in meters (Int16)
+- Compression: Deflate (zlib)
+- Internal tiles: 256×256 (225 tiles per file)