Traditional remote sensing uses stereopair or space transformation theory to position for ground based on ground control points which are surveyed in field or in map

but 3D remote sensing system applies GPS receiver

attitude measure unit and scanning laser rang finder to directly position for the remote sensing pixel which is captured simultaneously. Thus

it can obtain 3D position and remote sensing information of each ground point at the same time （almost in real-time）

from airborne test we can find 3D remote sensing directly positioning for ground is a breakthrough in remote sensing because it is fast. real-time and without ground control points.