Open Elevation

Batch query elevation data from the Open-Elevation public API. Supports single-point and multi-point queries by latitude/longitude coordinates. Outputs CSV or JSON. No API key required.

Query elevation (in meters) for any lat/lon coordinate on Earth using the free, public Open-Elevation API. No API key required.

Features

• Single-point elevation lookup
• Batch queries from CSV files (up to 100 points per API call)
• Automatic chunking for large datasets
• CSV and JSON output
• Input validation for coordinates

Usage

bash

# Single point
python scripts\open-elevation.py lookup --lat 39.9042 --lon 116.4074

# JSON output
python scripts\open-elevation.py lookup --lat 39.9042 --lon 116.4074 --json

# Batch from CSV
python scripts\open-elevation.py batch --input coords.csv --output results.csv

# Batch to JSON
python scripts\open-elevation.py batch --input coords.csv --output results.json --json

Installation

bash

pip install requests>=2.28.0 tqdm
# Or: pip install -r scripts/requirements.txt

Parameters

lookup

Argument	Required	Default	Description
--lat	Yes	—	Latitude (-90 to 90)
--lon	Yes	—	Longitude (-180 to 180)
--json	No	false	Output as JSON

batch

Argument	Required	Default	Description
--input	Yes	—	Input CSV path (must contain lat/lon or latitude/longitude columns)
--output	Yes	—	Output file path
--json	No	false	Output as JSON instead of CSV
--chunk	No	100	Points per API request (max 100)

Data Source

• API: Open-Elevation
• Endpoint: https://api.open-elevation.com/api/v1/lookup
• Coverage: Global
• License: Public domain
• Cost: Free, no key required
• Underlying data: SRTM (Shuttle Radar Topography Mission), AW3D30 (ALOS World 3D - 30m), and other sources
• CRS: WGS84 (EPSG:4326)
• Spatial resolution: ~30m (SRTM 1-arc second), varies by region
• Rate limit: Max 100 points per API request; be respectful of the public service
• Timeout: Default 30s per request; configurable via --timeout flag

Output Schema

CSV columns: latitude, longitude, elevation

JSON format:

json

{
  "results": [
    {"latitude": 39.9042, "longitude": 116.4074, "elevation": 43.5}
  ]
}

Ocean / Bathymetry Handling

• Ocean areas return elevation of 0 (sea level) or negative values (bathymetry) depending on data availability
• SRTM does not cover open ocean; ocean points may return 0

Citation

If you use SRTM data in publications, please cite:

bibtex

@misc{srtm2000,
  title = {Shuttle Radar Topography Mission (SRTM) Global Data},
  author = {{NASA Jet Propulsion Laboratory}},
  year = {2000},
  howpublished = {\url{https://www2.jpl.nasa.gov/srtm/}},
  note = {Accessed: YYYY-MM-DD}
}

Visualization

• Plot elevation profiles with matplotlib: plt.plot(distance, elevation)
• Create DEM heatmaps with imshow() using terrain colormaps (cmap='terrain')
• Overlay on maps with contextily or folium

Troubleshooting

Error	Cause	Solution
ConnectionError	Network issue	Check internet, retry
HTTP 429	Rate limit	Wait 60s, retry
ValueError	Invalid input	Check parameter format
Empty output	No data	Try different parameters
ModuleNotFoundError	Missing dep	Run pip install
Timeout	Slow network	Increase --timeout value
All zeros in ocean	No SRTM coverage	Expected behavior for ocean points

---

Advanced Usage

Large Batch Query with Retry

python

import csv, time, subprocess
with open('points.csv') as f:
    reader = csv.DictReader(f)
    for row in reader:
        for attempt in range(3):
            result = subprocess.run(
                ['python', 'scripts/open_elevation.py', 'lookup',
                 '--lat', row['lat'], '--lon', row['lon']],
                capture_output=True, text=True
            )
            if result.returncode == 0:
                break
            time.sleep(2 ** attempt)

CI/CD Integration (GitHub Actions)

yaml

# .github/workflows/elevation-update.yml
name: Elevation Data Update
on:
  workflow_dispatch:
jobs:
  query:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: '3.11'
      - run: |
          python scripts\open-elevation.py batch \
            --input points.csv --output elevations.json

PostgreSQL/PostGIS Import

bash

python scripts\open-elevation.py batch --input points.csv --output elevations.json

# Convert to CSV then import
python -c "import json, csv; d=json.load(open('elevations.json')); 
csv.writer(open('elev.csv','w',newline='')).writerows(
  [('lat','lon','elevation')] + [(p['lat'],p['lon'],p['elevation']) for p in d]
)"
psql -d gis_db -c "\COPY elevations(lat, lon, elevation) FROM 'elev.csv' CSV HEADER"

Performance Tips

• Batch mode accepts up to 100 points per request; chunk large files
• Add sleep 1 between batches to respect rate limits
• Ocean coordinates return 0m elevation — filter with WHERE elevation != 0

---

中文说明

使用免费的 Open-Elevation 公开 API 查询任意经纬度的海拔高度（米）。无需 API 密钥。

功能

• 单点高程查询
• 从 CSV 文件批量查询（每次 API 调用最多 100 点）
• 大数据集自动分块
• 支持 CSV 和 JSON 输出
• 坐标输入验证

使用方法

bash

# 单点查询
python scripts\open-elevation.py lookup --lat 39.9042 --lon 116.4074

# JSON 输出
python scripts\open-elevation.py lookup --lat 39.9042 --lon 116.4074 --json

# 批量查询
python scripts\open-elevation.py batch --input coords.csv --output results.csv

# 批量 JSON 输出
python scripts\open-elevation.py batch --input coords.csv --output results.json --json

数据来源

• API: Open-Elevation
• 端点: https://api.open-elevation.com/api/v1/lookup
• 覆盖范围: 全球
• 许可证: 公有领域
• 费用: 免费，无需密钥
• 底层数据: SRTM (航天飞机雷达地形测绘任务)、AW3D30 (ALOS World 3D - 30m) 等
• 坐标系: WGS84 (EPSG:4326)
• 空间分辨率: ~30m (SRTM 1角秒)，因地区而异
• 速率限制: 每次 API 请求最多 100 点；请尊重公共服务
• 超时: 默认 30 秒/请求；可通过 --timeout 参数配置

输出格式

CSV 列: latitude, longitude, elevation

JSON 格式:

json

{
  "results": [
    {"latitude": 39.9042, "longitude": 116.4074, "elevation": 43.5}
  ]
}

海洋/水深处理

• 海洋区域返回海拔 0（海平面）或负值（水深），取决于数据可用性
• SRTM 不覆盖开阔海洋；海洋点可能返回 0

引用格式

如果发表使用 SRTM 数据，请引用:

bibtex

@misc{srtm2000,
  title = {Shuttle Radar Topography Mission (SRTM) Global Data},
  author = {{NASA Jet Propulsion Laboratory}},
  year = {2000},
  howpublished = {\url{https://www2.jpl.nasa.gov/srtm/}},
  note = {Accessed: YYYY-MM-DD}
}

可视化

• 使用 matplotlib 绘制高程剖面: plt.plot(distance, elevation)
• 使用 imshow() + terrain 色标 (cmap='terrain') 创建 DEM 热力图
• 使用 contextily 或 folium 叠加到地图上

故障排除

错误	原因	解决方案
ConnectionError	网络问题	检查网络，重试
HTTP 429	速率限制	等待 60 秒后重试
ValueError	无效输入	检查参数格式
空输出	无数据	尝试不同参数
ModuleNotFoundError	缺少依赖	运行 pip install
超时	网络慢	增加 --timeout 值
海洋区域全为 0	SRTM 无覆盖	海洋点的预期行为