the clockwise horizontal angle measured about the ground nadir point from the ground survey North meridian in the plane of photograph.
orthomosaic
A high-resolution map created by orthophotos, usually via drones is termed as an orthomosaic. Ortho meaning a nadir image and mosaic meaning a collection of images.
Aerial surveys use a measuring camera where the elements of its interior orientation are known, but with much larger focal length and film and specialized lenses.
Aerial survey sensors
In order to carry out an aerial survey, a sensor needs to be fixed to the interior or exterior of the airborne platform with line-of-sight to the target; it is remotely sensing. With manned aircraft, this is accomplished either through an aperture in the skin of the aircraft or mounted externally on a wing strut. With unmanned aerial vehicles (UAVs), sensors are often mounted under or inside the vehicle, allowing for rapid data collection over challenging terrains, though sometimes with less precision than traditional methods.[3]
Aerial survey systems typically include the following components:
Flight navigation software to guide the pilot in flying the desired survey pattern.
GNSS, combining GPS and an inertial measurement unit (IMU) to provide accurate position and orientation data.
Gyro-stabilized mounts to counteract the effects of aircraft roll, pitch, and yaw.
Data storage units to securely save the recorded data.
Examples of aerial survey sensors
Vexcel UltraCam (Eagle,[4] Falcon, Osprey,[5] Condor) and their calibrations.[6]