座標 準拠 Audit Checklist 解説

Inaccurate coordinate data is a legal liability. Use this audit checklist to verify compliance before project delivery.

使い方

Run this checklist before every major data delivery or milestone.

オンラインツール

1. Metadata & EPSG Verification

  • [ ] EPSG Codes Present: Do all spatial files have a defined EPSG code? (No "Unknown CRS")
  • [ ] Version Check: Are you using the EPSG registry version specified in the contract?
  • [ ] WKT Validation: Is the Well-Known Text definition valid and complete?

2. Transformation Integrity

  • [ ] Transformation Defined: Is the specific transformation method (e.g., NTv2 grid) documented?
  • [ ] Grid Availability: Are the required grid shift files (.gsb) available to all team members?
  • [ ] Accuracy Validation: Has a "Round-Trip" test been performed (A -> B -> A) to verify precision loss?

Action: Run the Validation Flowchart if any item fails.

Datum Hazard: Read Before Conversion

Coordinate values only have meaning when attached to a Datum.

  • WGS84: Standard for GPS, Google Maps, Web Mercator (EPSG:3857, valid -85.05° to +85.05°).
  • NAD27: Used in older USGS topographic maps (pre-1983).

Using the wrong datum can shift your position by 20-100+ meters. Always verify the source datum of your coordinates.

ユースケース

専門家への相談が推奨される場合

For scenarios where self-check tools cannot mitigate risk, certified professional consultation is mandatory:

  • Critical infrastructure projects where datum mismatch exceeds 1cm.
  • Datasets involving trans-boundary legal boundaries or sovereign waters.
  • Situations where discrepancies exist between historical paper surveys and GNSS data.

See the Decision Boundary Guide for detailed risk thresholds.

FAQ

Q: Why is coordinate compliance necessary?

A: Non-compliant data causes integration failures and legal disputes. An audit trail proves due diligence.

Q: What standards does this cover?

A: It aligns with ISO 19111 (Referencing by Coordinates) and general OGC best practices.

Q: How often should I audit?

A: At project kickoff, creating new datasets, and final delivery.

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

米国平面直角座標系（SPCS）変換 & ガイド

各州固有の正角投影グリッドからGPS WGS84への高精度測量・工学座標変換。

測地技術リファレンス
公的測地パラメータ・技術文献に基づく解説

地殻変動と再施工リスク：NAD83 vs WGS84の累積誤差

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。

リスク指標: 2.2mの地殻変動とエポック累積ズレ
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