Determination of the Position and Orientation of Aerial Photogrammetry Sensors: A Practical Implementation

Surveying engineering aims at determining the three-dimensional positions of points on the earth surface. One of the techniques of achieving this is by making measurements on two-dimensional aerial photographs. This is known as Aerial Photogrammetry. Aerial Photogrammetry employs the use of aircraft such as aeroplane, helicopter, or in recent times, drone, to take photographs of places to be mapped from the air. In determining the required ground coordinates of an object by Aerial Photogrammetry, the position and attitude (orientation) of the sensor (or camera) during exposure must be known. The recovery of these parameters (exterior orientation parameters) is known as space resection. Although several texts and papers have described various methods of retrieving the parameters, and how to go about the solutions, the descriptions are vivid, and usually unclear to a large percentage of students. The solution involves tedious computational tasks and is generally time-consuming and brain-tasking. Hence, there is need to proffer a step-by-step solution to a real-world problem that students can study. This paper aims to implement this by employing images captured by an Unmanned Aerial Vehicle (UAV) and measured ground coordinates at the University of Lagos, Nigeria. With a view to achieving quick, less stressful and gross error-free solutions, a computer program was developed in C# programming language for the problem using the principle of collinearity condition