WGS84#

Use this skill for practical work with WGS 84 longitude/latitude coordinates.

WGS 84 usually refers to the global geographic reference system commonly exposed as EPSG:4326 in GIS software. It is the right default for GPS-style coordinate exchange, but it is not the right answer for every display or measurement workflow.

What This Skill Does#

• Explain what WGS 84 is and when to use it.
• Validate longitude/latitude numeric ranges.
• Check whether a coordinate pair is likely lon,lat or lat,lon.
• Recommend a UTM zone and EPSG code for projected analysis.
• Flag when a coordinate falls inside mainland-China extents where GCJ-02 / BD-09 confusion is common.
• Recommend whether to keep WGS84, use Web Mercator for display, or switch to a projected CRS for analysis.
• Explain when to keep data in EPSG:4326 and when to reproject.
• Hand off file-based reprojection steps to qgis when execution is required.

Standard Workflow#

1. Confirm whether the input is WGS 84 already, or just "GPS coordinates" by assumption.
2. State the expected tuple order explicitly: lon,lat or lat,lon.
3. Validate numeric ranges before discussing conversion.
4. Decide the task type:
   • storage or API exchange
   • web map display
   • distance/area/buffer analysis
   • regional engineering or survey workflow
5. Keep EPSG:4326 for exchange/storage unless the task needs projected units.
6. If analysis needs meters, recommend a suitable projected CRS such as a local CRS or UTM zone.

Practical Commands#

Validate a WGS84 coordinate pair#

bash

python3 {baseDir}/scripts/wgs84_tool.py validate --lon 116.4074 --lat 39.9042

Check whether a pair is probably lon,lat or lat,lon#

bash

python3 {baseDir}/scripts/wgs84_tool.py guess-order --a 116.4074 --b 39.9042
python3 {baseDir}/scripts/wgs84_tool.py guess-order --a 39.9042 --b 116.4074

Recommend a UTM zone and EPSG code from WGS84 coordinates#

bash

python3 {baseDir}/scripts/wgs84_tool.py utm --lon 116.4074 --lat 39.9042
python3 {baseDir}/scripts/wgs84_tool.py utm --lon -122.478255 --lat 37.819929

Flag China mapping offset risk#

bash

python3 {baseDir}/scripts/wgs84_tool.py china-check --lon 116.4074 --lat 39.9042

Recommend the right CRS for a concrete task#

bash

python3 {baseDir}/scripts/wgs84_tool.py recommend --lon 116.4074 --lat 39.9042 --task exchange
python3 {baseDir}/scripts/wgs84_tool.py recommend --lon 116.4074 --lat 39.9042 --task analysis
python3 {baseDir}/scripts/wgs84_tool.py recommend --lon 116.4074 --lat 39.9042 --task web-map

Decision Rules#

• Prefer EPSG:4326 for interoperable storage, APIs, logs, and exchange.
• Prefer a projected CRS in meters for buffering, area, distance, and nearest-neighbor analysis.
• Prefer EPSG:3857 only for web-map display compatibility, not for accurate measurement.
• Do not assume a pair is WGS 84 just because it contains two decimals; confirm source system when accuracy matters.
• Do not assume all systems interpret EPSG:4326 axis order the same way; many practical APIs use lon,lat even when standards prose differs.
• In mainland China workflows, explicitly check whether the source is raw WGS84 or app-level GCJ-02 / BD-09.
• Treat GCJ-02 and BD-09 as mapping offset systems, not simple aliases for EPSG:4326.

What To Return#

• The interpreted coordinate order.
• Whether the values are valid WGS84 longitude/latitude ranges.
• Whether keeping EPSG:4326 is appropriate for the task.
• If not, recommend the target CRS and explain why.
• If using UTM, provide zone number, hemisphere, and EPSG code.
• If the point is in mainland China, include a short warning about GCJ-02 / BD-09 ambiguity when relevant.

When Not To Use#

• Reverse geocoding or coordinates to address lookup: use geocode.
• File-based GIS conversion or batch reprojection: use qgis.
• General CRS comparison beyond WGS84-centered guidance: use project.
• Navigation routing, POI search, or map reviews.

OpenClaw + ClawHub Notes#

• Keep examples generic and reproducible.
• Do not hardcode private paths, real device traces, or private datasets.
• For clawhub.ai publication, keep versioning/changelog semver-driven and examples standards-based.

Reference Docs In This Skill#

• Read {baseDir}/references/wgs84-reference.md for concise CRS comparison and common failure cases.