> A challenge with doing it from the ground is that the drones will be quite small relative to the size of the image. Bright IR LEDs on the drones could possib

> A challenge with doing it from the ground is that the drones will be quite small relative to the size of the image. Bright IR LEDs on the drones could possibly help there. Even a visible light camera (with its IR filter) will pick up a strong NIR source. An IR camera will pick up the LEDs even better. They'll likely stand out pretty well against the sky and be straight forward to filter with some image processing.