From the ground, a forest can look like one solid green surface. From space, NASA's GEDI instrument sees something different: a three-dimensional structure made of tree tops, branches, leaves, and the ground below. GEDI is attached to the International Space Station, more than four hundred kilometres above Earth. NASA Earthdata lists its study dates from December fifth, two thousand eighteen, to the present. GEDI does not take an ordinary photograph. It sends laser pulses toward Earth and records the light that comes back. Because leaves, branches, and the ground reflect light from different heights, the returning signal can reveal the vertical shape of a forest. This kind of technology is called lidar, short for light detection and ranging. It is a little like using echoes to understand the shape of a room, except the signal is made of light and the room is a forest.
The laser map that sees forests in 3-D
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