"ELEMENTS OF INTERNAL AND EXTERNAL ORIENTATION OF AERIAL PHOTOGRAPHS"

Abstract:

Aerial photogrammetry has experienced a rapid transition from analog to fully digital workflows, yet the geometric foundations of internal and external orientation remain indispensable. Internal orientation fixes the camera’s internal geometry so that every image‐space measurement can be expressed in a detector‐-centred coordinate system, whereas external orientation establishes the six rigid-body parameters that tie each exposure station to a terrestrial reference frame. This paper synthesises current theoretical and practical knowledge of both orientation stages, traces their evolution from glass-plate cameras to tightly coupled GNSS/IMU-assisted sensor systems, and reports a controlled experiment that quantifies how refined camera calibration and rigorous ground control reduce final object-space errors. A 120-image block acquired with a medium-format metric camera on an uncrewed aerial vehicle (UAV) was processed twice: (a) with laboratory-derived interior parameters and dense ground control, and (b) with self-calibration and sparse control. The RMS object-space discrepancy dropped from 14.2 cm to 4.7 cm when precise interior parameters were enforced. Results confirm that meticulous treatment of both orientation steps is vital to meet contemporary accuracy requirements for large-scale topographic mapping and 3-D modelling.