Cross-check a mapped feature
Identify the feature and coordinates, compare public layers and select a satellite acquisition for the relevant date.
Documents to open in this workflow
This order suggests a starting point; revisit a step if identifiers, dates or versions disagree. Access and reuse terms depend on each service.
OpenStreetMap
Explore a collaborative map and geographic features described by contributors.
What to record
Feature type and identifier, version, tags, coordinates and access date.
Source-specific check
Compare the same feature version; an edit date is not necessarily a field-observation date.
Open source portalcartes.gouv.fr
Explore IGN maps, aerial photography and public territorial layers.
What to record
Area, coordinates, layer, producer, displayed scale and data date.
Source-specific check
The date you opened the map is not the date of its image or layer.
Open source portalCopernicus Browser
View and compare satellite imagery and metadata over time.
What to record
Product identifier, sensor, acquisition date, area, resolution, cloud cover and processing applied.
Source-specific check
Publication and acquisition dates differ; inspect clouds over the precise area of interest.
Open source portal
Matching condition
Link object identifier, geometry, layer and date; document reference system before overlay.
If results disagree
For different positions, check precision and point versus boundary before inferring actual movement.
Output to produce
Table of objects, coordinates, layers and dates.
Separate documentary evidence, demonstrated links between documents and remaining inference. State the owner and review trigger.
Supporting methods
Producer references
Matching table to complete
This is a blank template, not a research result. Record the exact item and observation for each source before making the decision.
| Source | Document or exact URL | Date and version | Observation and passage | Scope and limit | Link established or unestablished |
|---|---|---|---|---|---|
| OpenStreetMap | To record | To record | To record | To record | To record |
| cartes.gouv.fr | To record | To record | To record | To record | To record |
| Copernicus Browser | To record | To record | To record | To record | To record |
Frequently asked questions
What link should be checked before matching results?
Link object identifier, geometry, layer and date; document reference system before overlay.
What if sources appear to contradict each other?
For different positions, check precision and point versus boundary before inferring actual movement.
Do the listed portals provide independent confirmation?
Not necessarily. Identify the producer and underlying document. Two interfaces distributing one item can check transcription but do not establish a fact independently twice.