Off-nadir viewing (SPOT HRV).

• Each HRV’s viewing mirror can be commanded from the ground to tilt up to ±27° off vertical.
• Advantage 1 — stereoscopic imagery. Two images of the same ground target from different angles produce parallax, which lets you derive elevation (DEMs, 3D models).
• Advantage 2 — shorter revisit. At mid-latitudes, the effective revisit drops from the 26-day nadir cycle to 1–4 (5) days.