Project

Use this skill for geographic coordinate system and projection questions.

Scope

• Explain what a CRS/projection is and why it matters.
• Compare common systems such as EPSG:4326, EPSG:3857, UTM zones, CGCS2000, GCJ-02, and BD-09.
• Recommend a target CRS based on the task: storage, web map display, measurement, analysis, or exchange.
• Review conversion plans and call out likely mistakes such as swapped axis order, wrong units, or datum mismatch.

Workflow

1. Identify the source coordinate system, target coordinate system, and the actual job to be done.
2. State whether the user needs a geographic CRS, projected CRS, or a provider-specific offset system.
3. Call out the important differences: datum, units, axis order, extent, and whether the transform is exact or approximate.
4. Give a concrete recommendation with an EPSG code or named system when possible.
5. If the request involves local files or batch conversion, hand off execution details to qgis.