A real camera in the loop
RETINA, the Realistic Experimental faciliTy for vIsion-based NAvigation, is DART's variable-magnification optical hardware-in-the-loop (HIL) facility. It supports verification and validation (V&V) of spaceborne cameras, image processing, and vision-based navigation (VBN) by presenting a controlled optical scene to a real camera.
A numerical environment generates the scene associated with a simulated spacecraft state. A high-resolution display presents the image through a dedicated optical system, and the camera records the resulting stimulus. The experiment therefore captures the response of the camera and its interaction with the optical chain.
Variable optical configuration
RETINA's variable-magnification design adapts the optical stimulation to cameras with different fields of view without rebuilding the complete facility. The optical bench operates in a controlled dark environment, where the display, lens system, and camera are aligned and characterized as one acquisition chain.
Geometric calibration accounts for alignment and optical effects that shift or distort image features. Radiometric calibration relates the stimulated scene to the intensity response captured by the camera. These procedures support experiments that require repeatable image geometry and brightness.
Role in the EXTREMA Simulation Hub
Within the EXTREMA Simulation Hub (ESH), RETINA provides the physical sensing path for optical navigation. The simulated spacecraft state determines the rendered scene, RETINA presents it to the camera, and the onboard navigation software processes the acquired image. The resulting estimate can then influence guidance and control in the same closed-loop experiment.
Typical uses include camera characterization, calibration verification, image-processing regression tests, VBN algorithm validation, and end-to-end autonomous GNC experiments.