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?

NO →

YES ↓

STOP: Ambiguous Data
Ask provider for source datum.

Is Operation "Calculation"?
(Distance, Area, Buffer)

YES ↓

Is CRS Projected & Preserving?
(UTM, State Plane, Albers)

NO (Lat/Lon or Web Mercator) →

YES ↓

STOP: Projection Error Risk
Reproject to UTM/Local before calc.

PROCEED S AFELY

Mandatory Tolerance & Accuracy Invariants

Before releasing data, you shall verify the following numeric tolerances against your Accuracy Class:

1. Network Accuracy (Global)

Check against National CORS/Benchmarks.
Limit: Must meet 95% Confidence Interval (e.g., 2cm for RTK).

2. Local Accuracy (Closure)

Check Misclosure of Traverse/Loops.
Action: Adjust residuals only if within rejection criteria.

3. Independent Check

Compare against 20+ check points not used in control.
Result: Calculate RMSE (Root Mean Square Error).

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 Tools

US State Plane (SPCS) Converters & Local Guides

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