Read a map and local indicator
Connect legend, scale, date, territory and method without treating a colour as an individual measurement.
Prepare the task
A map or index describes a territory through a method. A precise-looking display may still have limits in date, coverage and resolution.
- Question and intended area
- Map or indicator with its legend
- Date or validity period
Follow the method
- 1Identify layers
Record background map, layer and producer. Check whether the data is an observation, forecast or administrative description.
- 2Read the reference points
Inspect legend, unit, scale and date. Do not treat colours from different methods as equivalent measurements.
- 3State the scope
Explain what the indicator says about the area and what it cannot measure for a person or exact point. Keep documentation with the map.
Two maps show different colours on the same day: compare pollutant, period, method and area before calling them contradictory.
Choose the resource for the missing evidence
The directory records identify publishers and link to their official services. Choose by task; inclusion does not guarantee an outcome.
| Task | Resource | Check |
|---|---|---|
| Explore a background or layer | Cartes.gouv.fr (ancien Géoportail) | Read date, producer and scale. |
| Understand an air-quality index | Atmo France | Read territory, period and method. |
| Explore environmental data | Copernicus | Check product, resolution and documentation. |
Compare these directory resources side by side →
A completed record to understand the method
Fictional example: values, times and situations below demonstrate how to document a decision. They do not describe an actual service or application.
| Element | Observation in the example | Next action |
|---|---|---|
| Map | Coloured area on a municipal boundary | Identify variable and legend |
| Table | Value from another year | Align periods before comparison |
| Location | Point near a boundary | Check the exact area; do not infer an address from colour alone |
Keep a useful record
Use these fields in your own notes. This page does not collect your documents or personal details.
- Map, layer and producer
- Period and territory
- Legend, unit and resolution
- Conclusion within the stated scope
Read these points directly on this page.
Do not use a territorial index as a guaranteed measure of individual exposure; read the competent source’s instructions.
Common questions
Can I average colours?
Read the indicator method; colours are categories, not arbitrary numerical measurements.
Is a detailed map recent?
Visual detail does not establish the data’s date or period.
The basemap is recent but the data layer is older. Which date matters?
Record the basemap date, indicator period and layer update separately. When discussing a value, use the corresponding measurement period. Recently drawn roads do not establish the date of observations displayed over them.
A point sits at the centre of an area. Does it give an exact address?
Read the layer’s geographic definition and positioning method. A point may represent an entire area. If precision is undocumented, keep the area-level interpretation and avoid treating the visual position as the exact location of a person or event.