Coordinate Validation Decision Tree

Should you proceed with calculation? Or do you need to stop and verify? Use this logic flow to make safe decisions about your geospatial data.

How to Use

Start at the top block. Verify each condition. If you hit a 'STOP' condition, fix the data before proceeding.

Online Tool

START: Receive Data
Has EPSG Code / CRS Metadata?

4. The "Satellite Match" Test

Mathematical precision is useless if your map is wrong. You MUST verify:

Step A: Overlay

Import points into Google Earth or ArcGIS Earth.

Step B: Visual Check

Do points land on the intended physical feature (e.g., manhole, corner)?

INVALID IF: Points shift > 1 meter from visual feature.
(Likely Datum Shift: WGS84 vs Local Grid)

Use Cases

  • Deciding whether to perform a datum transformation.
  • Training new staff on data acceptance procedures.

FAQ

Q: What is the 'Ambiguity Trap'?

A: It's when coordinates lack metadata (EPSG). You assume WGS84, but it was actually NAD27. The flowchart forces you to stop if metadata is missing.

Q: Why stop for epoch differences?

A: For high-precision work (cm-level), different time epochs mean different physical positions due to tectonic plate movement.

Q: Can I automate this flow?

A: Yes! This logic is ideal for building automated Python/ETL scripts for data ingestion pipelines.

Professional Verification Disclaimer

This content is provided for decision-support and educational purposes for geospatial professionals and does not constitute legal, surveying, or engineering advice. Regulations and official standards vary by jurisdiction and project scope. Information is based on publicly available standards as of January 11, 2026. For critical projects, always verify current requirements with:

  • Licensed Professional Surveyors or Professional Engineers (PE) in the relevant jurisdiction
  • Certified attorneys for legal interpretation of regulations
  • Current guidelines from relevant authorities (FAA, JCAB, GSI, etc.)

Reference: Professional Use & Scope

Related Coordinate Conversion ツール一覧

US State Plane (SPCS) Converters & Local Guides

Professional engineering and surveying transformations from state-specific conformal grids to GPS WGS84.

専門家による測地検証済み
専門的な測地基準に準拠して検証済み

The $50,000 Geodetic Drift Liability: NAD83 vs WGS84

北米プレートは年間約2cm移動するため、NAD83(2011)とWGS84(G1762)は現在2.2メートル以上乖離しています。 高精度なNAD83地籍杭打ちに「標準的な」GPS WGS84座標を使用したことで、基礎のやり直しやインフラの配置ミスによる5万ドルの専門家責任賠償請求が発生しています。

Risk Exposure Metric: 2.2-Meter Tectonic Drift & Epoch Accumulation
Professional Knowledge Graph:

重要：計算結果の正確性を確認してください

座標精度はデバイスや測地系によって異なります。以下の確認を行わずに実務で使用しないでください：

GPS精度の警告

スマホのGPSは最大30メートルずれることがあります。これが原因でデータに重大なエラーが発生します。

精度を今すぐチェック

測地系のリスク

誤った測地系（例：WGS84と日本測地系）を使用すると、常に数百メートルのズレが生じます。

測地系を確認する