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    Comparison of GPU-based Methods for Handling Point Cloud Occlusion
    (The Eurographics Association, 2021) López, Alfonso; Jurado, Juan Manuel; Padrón, Emilio José; Ogayar, Carlos Javier; Feito, Francisco Ramón; Ortega, Lidia M. and Chica, Antonio
    Three-dimensional point clouds have conventionally been used along with several sources of information. This fusion can be performed by projecting the point cloud into the image plane and retrieving additional data for each point. Nevertheless, the raw projection omits the occlusion caused by foreground surfaces, thus assigning wrong information to 3D points. For large point clouds, testing the occlusion of each point from every viewpoint is a time-consuming task. Hence, we propose several algorithms implemented in GPU and based on the use of z-buffers. Given the size of nowadays point clouds, we also adapt our methodologies to commodity hardware by splitting the point cloud into several chunks. Finally, we compare their performance through the response time.
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    A Usability Study for a Novel Approach to Virtual Reality Interaction
    (The Eurographics Association, 2018) Negrillo, José; Jiménez, Juan Roberto; Feito, Francisco Ramón; García-Fernández, Ignacio and Ureña, Carlos
    The number of virtual reality-based systems have considerably increased in recent years due to many technical improvements and lower prices. Nowadays, the applications of this kind of systems go further than videogames. Additionally, they enable new interaction paradigms adapted to this new technology. In this paper we propose a new interaction model to visualize objects in a virtual reality context. We describe our proposed mechanisms to achieve a set of graphical tasks and we conduct an experiment to assess the usability of the system, comparing it to other traditional methods.
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    3D Mapping Approach to Analyze the Evolution of Vegetation Using Multispectral Imagery
    (The Eurographics Association, 2018) Jurado, Juan Manuel; Ortega, Lidia; Feito, Francisco Ramón; García-Fernández, Ignacio and Ureña, Carlos
    The 3D simulation for the evolution process of crop types requires the management of large volume of data to make an accurate analysis of functional and structural vegetation characteristics. In fact, current geomatics technologies allow the capture of massive and heterogeneous data with a great spatial resolution. Regarding research advances for precision agriculture applications Unmanned Aerial Vehicles (UAV)-based remote sensing offers great possibilities to acquire field data in a fast and reliable way. The main aim of this paper is twofold: (1) the study of multispectral imaging from UAVs for reflectance maps calculation, (2) 3D mapping and modeling using RGB and multispectral imagery in order to create a 3D NDVI (Normalized Difference Vegetation Index) point cloud. We are focussed on 4D inspection of olive trees including spatio-temporal data for reflectance change detection in multispectral remote sensing images.