What is CE90?

CE90 (Circular Error 90%) is a standard geospatial accuracy metric indicating that: 90% of points in the imagery are located within a specified distance of their true position on the ground.

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

SkySat Accuracy Specifications

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

1. Orthorectified Imagery (Analysis-Ready)

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

• Typical CE90: ~10–15 meters
• Typical RMSE specification: <10 meters
• Best suited for:
  • Mapping and GIS overlay
  • Change detection
  • General measurement and analysis

2. Basic Imagery (Sensor Geometry Only)

Basic SkySat imagery is processed using onboard satellite telemetry (e.g., GPS and attitude sensors) without terrain correction or external ground control.

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

Why Does This Matter?

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

Higher accuracy is especially important for:

• Multi-temporal analysis (e.g., 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 (~10–15 m CE90).

If your workflow requires higher alignment precision, consider:

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