A Fast, Three-Dimensional, Indirect Geolocation Method Using IAGM and DSM Data without GCPs for Spaceborne SAR Images

Area of Science:

• Remote Sensing
• Geospatial Analysis
• Photogrammetry

Background:

• Traditional indirect geolocation methods for spaceborne synthetic aperture radar (SAR) images are computationally intensive.
• Accurate geolocation is crucial for precise analysis and application of SAR data.
• Reliance on ground control points (GCPs) can be resource-prohibitive and time-consuming.

Purpose of the Study:

• To develop a fast, three-dimensional (3D), indirect geolocation method for spaceborne SAR images.
• To eliminate the need for ground control points (GCPs) in the geolocation process.
• To improve computational efficiency while maintaining geolocation accuracy.

Main Methods:

• Introduction of the Range-Doppler (RD) geolocation model within the Earth-centered rotating (ECR) coordinate system.
• Application of an iterative analytical geolocation method (IAGM) to determine SAR image corner point locations.
• Construction of a 3D grid using digital surface model (DSM) data and estimation of pixel azimuth time for reduced Doppler centroid calculation.

Main Results:

• The proposed method demonstrates a significant speed improvement, being approximately 12 times faster than traditional methods.
• The method maintains high geolocation accuracy for spaceborne SAR images.
• Precise azimuth time estimation facilitates accurate range location determination.

Conclusions:

• The developed 3D indirect geolocation method offers a computationally efficient alternative for spaceborne SAR image geolocating.
• Accurate geolocation is achievable without GCPs by leveraging high-resolution DSM data.
• This technique enables precise geolocating of SAR images to the Earth's surface.