Verification of drone imagery footprint geometry calculation

Abstract Nowadays, drone imagery is a common way to quickly obtain information on the state of vegetation, as well as a method for taking orthophotos and terrain models. For terrain modelling, aerial photographs are required to have at least 60% overlap between adjacent images. Typically, the inadequate overlap is only discovered later, during post-processing. In our previous work we have presented a method we developed to determine on the spot, whether the in-flight images are suitable for producing the terrain model or whether it is necessary to re-render a part of the area, which can be done under the same conditions (weather, ionosphere, satellite geometry). Our proposed method for calculating the overlap is different from the usual procedure. Using VBA-based calculations, we computed the overlap between the images based on the position of the centre of the images, the altitude of the flight and the rotation angle of the images. The method was tested in practice, but we felt it necessary to verify our calculations. During the verification, we checked the VBA-based calculations using a Python script. The test showed that the results obtained with a previous midpoint calculation method were 92.2 percent identical to the calculations performed with Python. The Python program is accurate and fast; therefore, the use is recommended on the field.