Polygon (plot boundary)

Why does it matter?

A polygon shows the full extent of a plot of land. Deforestation checks compare that area with forest maps; a point can only say whether one spot was forest. Polygons also allow area calculation, which supports yield plausibility checks and fraud detection.

The EUDR makes polygons mandatory above four hectares (Article 2(28)) and asks the Commission to evaluate that threshold in its 2030 review.

How does it work in practice?

A valid polygon, in the sense of the OGC Simple Features standard, is a closed ring whose first and last points are identical and whose edges do not cross. In GeoJSON, polygons use longitude-latitude order in the WGS 84 coordinate system.

Quality checks typically include:

• closure and minimum number of vertices;
• no self-intersection;
• no overlap with other farmers’ plots;
• plausible area compared to declared size;
• location within the declared country and region;
• GPS accuracy sufficient for the plot size.

Common pitfalls

• Walking only part of the boundary, then closing across the plot.
• Recording one polygon for several non-contiguous fields.
• GPS drift under dense canopy producing jagged, spiky outlines.
• Simplifying geometry so much that the shape no longer matches reality.

Farmer1st captures, validates and corrects polygons from field apps, files or imagery through its geo and polygons service.