Reference

Positional accuracy (CE90)

How closely a pixel's reported geographic position matches its true ground position. Reported as CE90 — the radius within which 90% of points fall.

WorldView-3 · Pléiades Neo< 5 m CE90CE90Sentinel-2 · Landsat 9~ 12 m CE90CE90true positionmeasured positionsCE90 ring · 90% of points
Fig. 1 Circular Error 90 (CE90) is the radius within which 90% of measured positions fall around the true location. WorldView-3 reports <5 m CE90. Sentinel-2 is ~12 m. Beijing-3N is ~10 m. For change detection, co-registration error between two acquisitions stacks — it is the root-sum-square of each scene's CE90.

Positional accuracy is reported as CE90 (Circular Error 90%) — meaning that 90% of pixels are within the stated distance of their true location. WorldView-3 has < 5 m CE90. Sentinel-2 has 8 m CE95. Lower numbers are better. This is the absolute accuracy without ground control points.

When it matters

For change detection, the relative alignment between two dates of the same sensor matters more than absolute accuracy — both images carry the same systematic error so they overlap correctly. For multi-sensor work or ground truth comparison, absolute accuracy matters. For any use where pixels are being measured against an external reference (cadastral boundaries, infrastructure positions), absolute accuracy matters.

Improving accuracy

Ground control points (GCPs) tied to known surveyed positions can dramatically improve effective accuracy — often to sub-pixel. We can use your GCPs in our orthorectification pipeline at no extra cost.