What is CE90?

CE90 (Circular Error 90%) is a standard geolocation accuracy metric. It indicates that 90% of points in an image are located within a specified distance of their true position on the ground.

It is commonly used to describe the absolute horizontal accuracy of satellite imagery.

SkySat accuracy specifications

The geolocation accuracy of SkySat® imagery from Planet depends on the level of processing applied to the data.

Orthorectified imagery (analysis-ready)

Orthorectified SkySat imagery is corrected for terrain and sensor geometry using Rational Polynomial Coefficients (RPCs) and Digital Elevation Models (DEMs). Additional refinement with Ground Control Points (GCPs) can be applied in some workflows.

• Typical CE90: 10 – 15 meters.
• Typical RMSE specification: less than 10 meters.
• Best suited for:
  • Mapping and GIS overlay.
  • Change detection.
  • Feature measurement and analysis.

Basic imagery (sensor geometry only)

Basic SkySat imagery is processed using onboard satellite telemetry, such as GPS and attitude sensors, without terrain correction or external ground control.

• Typical CE90: tens of meters, up to about 100 meters.
• Best suited for:
  • Custom orthorectification workflows.
  • Users applying their own DEMs or GCPs.
  • Advanced processing pipelines.

Why this matters

Geolocation accuracy determines how well imagery aligns with real-world coordinates and with other datasets.

Higher accuracy is especially important for:

• Multi-temporal analysis, such as tracking changes over time.
• Overlaying imagery with GIS layers.
• Avoiding apparent shifts caused by positional error.

Getting the most out of your data

For most applications, orthorectified SkySat imagery provides sufficient accuracy, at about 10 – 15 meters CE90.

If your workflow requires higher alignment accuracy, consider:

• Applying Ground Control Points (GCPs).
• Performing image-to-image co-registration.
• Using higher-quality elevation data.