In a previous article "Geo Hound: A Tool to Automatically Fetch Website Map Service Addresses", I introduced the powerful Geo Hound tool. Follow-up articles like "Get Hidden Government Map Data in 2 Steps (Geo Hound + Wuhan One Map)" and "Shanghai One Map Data (Trial)" shared practical experiences. Many readers subsequently asked: Can this map data be downloaded for offline use? While various methods exist, I'll share my two most-used approaches.
Method 1: Using QGIS (Recommended for Compatible Services)
This is my go-to method. Using Wuhan One Map as an example (Note: As of publication, direct access via QGIS has been disabled by Wuhan authorities. Replace with other sources. This guide is for educational purposes only. Do not download or disseminate confidential data):
- Open QGIS and load the Wuhan One Map service (obtained via Geo Hound).
- Right-click the layer >
Export
>Save As...
. Critical Settings:
- Uncheck Create VRT
- Set desired output resolution.
- Click
OK
. Exporting large areas takes significant time. - Result: A local raster file (~400 MB in this example). Select an appropriate area to avoid excessive file sizes.
Method 2: Manual Tiling + Vectorization (The "Fallback" Method)
This universal approach works for almost any web-accessible map. Let's use Shenzhen One Map (https://pnr.sz.gov.cn/d-xgmap/
) as an example (Geo Hound can identify this source, but direct QGIS loading may fail).
Principle: Data viewable in a web browser can be captured, though effort varies with required resolution.
Simplest Approach (Low Res):
- Visit the map service.
- Open browser developer console (Chrome recommended). Remove distracting elements/layers.
Capture the cleaned map view:
- Option A: Basic screenshot.
- Option B (Better): Select the map node in Elements inspector. Press
Ctrl+Shift+P
(Win/Linux) orCmd+Shift+P
(Mac). Search for and runCapture node screenshot
.
- Option A: Basic screenshot.
Higher Effort Approach (Higher Res):
- Use browser tools (e.g., Network tab) to capture all individual map tiles (
*.png
/*.jpg
). - Assemble tiles manually using software like GIMP or Photoshop (like a puzzle).
Georeference the Image:
Import the stitched image into QGIS. Use Layer
> Georeferencer
to assign real-world coordinates.
Conclusion
- Use dedicated map downloaders where possible. They're efficient.
- Method 1 (QGIS Export) is best for compatible services, but avoid massive datasets.
- Method 2 is a proof-of-concept fallback for difficult cases. It's less recommended due to high effort and potential quality issues.
- CRITICAL: Do not use these methods to download copyrighted, proprietary, or confidential data! Always prioritize legal data acquisition channels.
What methods do YOU use? Share in the comments!