SIMBIO-SYS/STC stereo camera calibration: Geometrical distortion

Area of Science:

• Planetary Science
• Space Instrumentation
• Optical Engineering

Background:

• The STereo imaging Channel (STC) is the first push-frame stereo camera on a European Space Agency (ESA) satellite, part of the BepiColombo mission to Mercury.
• Launched in 2018, STC aims to create a global 3D reconstruction of Mercury's surface upon arrival in 2025.

Purpose of the Study:

• To describe the geometrical calibration of the STC instrument.
• To present the methods for deriving focal lengths, boresights, and reference systems for STC's filter models.
• To discuss the distortion results and the development of a distortion map model.

Main Methods:

• Geometrical calibration of the STC instrument, including optical setups.
• Derivation of focal lengths, boresights, and reference systems for six filters (two panchromatic, four broadband).
• Development and application of the Rational Function Model (RFM) for distortion mapping due to the off-axis configuration.

Main Results:

• Successful geometrical calibration of the STC instrument.
• Determination of key optical parameters and reference systems for all filters.
• Demonstration of the RFM's capability to model complex distortions in off-axis stereo cameras.

Conclusions:

• The geometrical calibration and distortion modeling of the STC are crucial for accurate 3D surface reconstruction of Mercury.
• The Rational Function Model (RFM) proves effective for characterizing the distortions of the STC's unique optical design.
• This work validates the STC's readiness for its mission objectives in mapping Mercury's surface.