03
Section 03
Scale & Generalisation
What tolerance deletes.
4 entries. Each one names what the choice keeps and what it wrecks.
Plate 01The same ground published twice, with contours and without. What a sheet leaves out is a decision about its purpose.
Photo: Topographic and planimetric sheets, Fort Bragg · Wikimedia Commons
The entries
The length of a coastline
Measure with a shorter ruler and it gets longer, without limit. Which means a coastline has no single length, only a length at a scale.
Tolerance, and what it deletes
Simplification thresholds remove the smallest features first — which are often the ones that identify the place.
Simplify, smooth, displace
Three different operations regularly confused for one.
One geometry, many scales
The same data cannot serve every zoom without being generalised for each.
Next section — 04 Tiles & Zoom
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