## 1 Introduction  
In recent years, digital images and videos have allowed the consideration of virtualization as a tool to ease the access of visual information of objects/territories. It is easy to obtain virtual itineraries that permit the visualization of all types of locations, thus providing a tremendously accurate image of the place that is visited, even if it is miles of kilometers away from the user. This virtualization provides a large number of advantages, and, although the accessibility to information may be the most important one, since after the virtualization, it can be broadcasted in a practically worldwide way, there is another one of great importance. If the virtualization is developed in an appropriate way, it does allow not only a visual replication of all the elements that exist on a certain location but also their metric representation. This permits agents to prospect, investigate, manage, or even reproduce the asset. Due to all these reasons, the metric aspects are so important for a virtual recreation. The metric component of the virtualization has been widely developed in recent years, due to the emergence of several surveying techniques that allow modeling objects/territories [1], such as remote sensing, lidar, laser scanner, etc. Photogrammetry with UAVs (Unmanned Aerial Vehicles) has become a tool with great potential for several areas, such as agriculture, geology, engineering, or archaeology. This is due to the characteristics that this kind of vehicles offer, i.e., reduced size and weight, low cost, and easy handling [2]. This type of platforms allows collecting the information (aerial photographs) that is required for the generation of point-clouds and 3D models, which, after the application of the matching texture, lead to the recreation of orthomosaics, interactive PDFs, virtual itineraries through the model, etc. [3]. Therefore, the models themselves are the resources that are required for a virtualization of the object/territory with not only good visual appearance but also a proper metric that permits measuring, and the images obtained with UAVs are adequate for the traditional photogrammetric activities, due to their great resolution and the capacity to cover large areas with low costs. This supports their noticeable potential for archaeological surveying [4]. The generation of 3D models of the territory with UAVs is nourished by the images that the sensor comprised by the drone can capture, which must have enough quality according to the archaeological asset that is under study, and the process must be economically proportional. Hence, the acquisition of aerial photographs must be developed in an adequate way that guarantees the desired accuracy and level of detail, and their quality will depend on the flight during which they are taken [5]. This flight or mission must be previously defined by the pilot, according to the features of the sensor, and technical characteristics of the photogrammetric flight. This is usually developed by generic software, as it does not depend on the application for which the model is intended. Traditional aerial photogrammetry has covered a larger way in time, and parameters for the design and dimensioning of the flight project have been set according to the recommendations of several authors, or standardized charts. When working with UAV platforms, there is not specific information that establishes a methodology to dimension the photogrammetric flight projects for the acquisition of images with suitable quality for the generation of the final products. It is frequently assumed that a poor quality is related to the technical limitations of the platforms, instead of interpreting the dependence of the result with respect to design parameters. The definition of these technical factors is extremely important, due to its influence not only on the image resolution, but also on the management of the images, and the final products [6]. The analysis of the dependence between the final result and the initially fixed parameters is highly important.