In-depth practical guides

Check coordinates before placing them on a map

Check axes, units, reference system and precision before creating a GeoJSON point.

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Does the pair describe the location you intend?

Decimal-degree latitude and longitude differ from projected coordinates in metres. A point within numeric bounds may still be swapped, shifted or imprecise. Start with source documentation.

  1. Identify the reference system

    Find coordinate system, units and axis order. Do not infer WGS 84 from two small numbers; conversion needs the original reference system.

  2. Check both axes

    Latitude ranges from −90 to 90 degrees and longitude from −180 to 180. RFC 7946 GeoJSON uses longitude first, latitude second.

  3. Preserve stated precision

    Keep original text, measurement method and uncertainty. More decimals do not improve a measurement; a centroid need not identify a building entrance.

  4. Check documentary context

    Compare extent, date, layer and description. Near the antimeridian, avoid conclusions based on simple longitude differences.

Build a numerically checked GeoJSON point

Enter latitude and longitude separately. Local check with no external map or coordinate transmission by the tool.

Decimal dot or comma accepted; no thousands separator, degree sign or degrees-minutes-seconds notation. Export order is longitude, latitude. Bounds check neither location nor precision.

Ready to check.

Situations and decisions

Typical situations for preparing a check. They do not describe completed assignments or actual observations.

Two plausible axes

Fictional latitude 12, longitude 8 satisfies bounds, as does its reversal. Bounds cannot decide order; read field names.

Excess digits

An illustrative location rounded to one degree is copied with six decimals. The longer format creates no additional geographic precision.

Record to retain

  • Original pair and field names
  • Reference system, unit and axes
  • Date, method and uncertainty
  • Transformation and checking record

Official references

Related source profiles

Related protocols

Checks before reaching a conclusion

  • Is the reference system documented?
  • Is axis order explicit?
  • Does precision come from the source?
  • Do date and extent match the case?

A point with a note stating reference system and location limits.

Frequently asked questions

Do values within bounds establish a place?

No. Swapped axes may remain plausible. Check documentation, context and the selected layer.

Can RFC 7946 GeoJSON declare a local projection instead of WGS 84?

It uses geographic positions in degrees under WGS 84. Transform projected data with a suitable tool first and retain the operation.

TOOLS / REGISTERS

Write a record

Compare extent, date, layer and description. Near the antimeridian, avoid conclusions based on simple longitude differences.

  • Access date and time zone
  • Exact URL
  • Observed passage / value
  • Exact column name
  • Unit / calculation basis
  • Method / definition
  • Version / revision
  • Observed status
  • Limit / uncertainty
  • Decision / next action
  • Review owner
  • Next review
Write an observationDownload CSV template