Atlas · South Africa / Methodologies
METHODOLOGIES

How units are harmonised on import

Areas to hectares, lengths to metres, dates to UTC; unclear units are excluded and recomputed from geometry.

Intermediate 1 min read unitsimportdata qualityhectares

Source layers use a mixture of units: hectares, square kilometres, square metres, degrees, percentages, local date formats. Atlas converts them as follows and records every rule in the dataset's unit map.

Source value Rule
Area named ha / hectares Kept (unit taken from the field name)
Area named km², sq km × 100 → hectares
Area named m² × 0.0001 → hectares
Shape_Area, Shape_Length Excluded: units are not stated (often degrees); area and length are recalculated from the geometry
Length in km × 1,000 → metres
Percent fields Kept 0–100; values outside the range are rejected and the original kept
Esri dates (epoch milliseconds) Converted to ISO-8601 UTC
Blank text (" ") Converted to empty
Coded values Replaced by their labels, code kept

Originals are never thrown away. The original attributes are stored in the source record and each converted number keeps its original value and unit.

Why Shape_Area is excluded. In geographic coordinates it is measured in square degrees, which is meaningless (a degree is a different distance at every latitude). Atlas computes true hectares from the shape instead.

Limits. A field named "area" with no unit is stored as an attribute but not converted.

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