Aerial triangulation is the most significant part of a photogrammetry project and will be performed using the Match-AT module of any photogrammetry software. It followed by some conventional steps. Interior orientation (IO) will be established using camera calibration report. The initial approximate exterior orientation (EO) will be established using the Airborne Global Positioning System (AGPS) and Inertial Measurement Unit (IMU) data acquired.
Video by ASPRS on Aerial Triangulation
In aerial triangulation, tie points and control points will be measured manually. Tie Points extraction and correction are done automatically and the final results need to check for distribution, number and completeness of the observations. Final AT result will be computed and it will be experienced further using Bundle Block Adjustment. So this is most important part of any photogrammetry project.