# CRS Sanity Check

> Validate coordinate systems, units, and reprojection assumptions before analysis.

- Skill: `georetina/crs-sanity-check` (Agent Skill)
- Install (CLI): `npx skillmds@latest add georetina/crs-sanity-check`
- Raw SKILL.md: https://api.skillmd.com/api/skills/georetina/crs-sanity-check/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: georetina (https://skillmd.com/u/georetina)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/georetina/crs-sanity-check

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# CRS Sanity Check

## When To Use

- Use before any overlay, buffer, distance, or area operation.
- Use when data comes from multiple providers or mixed formats.
- Use when coordinate metadata is missing or contradictory.

## Workflow

1. Inspect declared CRS for every input layer.
2. Confirm axis order and unit assumptions.
3. Identify a shared analysis CRS and justify it.
4. Reproject inputs only once to the selected CRS.
5. Validate extents and spot-check coordinates after reprojection.

## Guardrails

- Do not compute distance or area in geographic degrees unless explicitly intended.
- Do not proceed when CRS metadata is absent without an explicit fallback strategy.
- Record original CRS and transformation choices in the final output notes.