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Now showing 1 - 4 of 4
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    Tree Variations
    (The Eurographics Association, 2017) Argudo, Oscar; Andújar, Carlos; Chica, Antoni; Fco. Javier Melero and Nuria Pelechano
    The cost-effective generation of realistic vegetation is still a challenging topic in computer graphics. The simplest representation of a tree consists of a single texture-mapped billboard. Although a tree billboard does not support top views, this is the most common representation for still image generation in areas such as architecture rendering. In this paper we present a new approach to generate new tree models from a small collection of RGBA images of trees. Key ingredients of our method are the representation of the tree contour space with a small set of basis vectors, the automatic crown/trunk segmentation, and the continuous transfer of RGBA color from the exemplar images to the synthetic target. Our algorithm allows the efficient generation of an arbitrary number of tree variations and thus provides a fast solution to add variety among trees in outdoor scenes.
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    Depth Map Repairing for Building Reconstruction
    (The Eurographics Association, 2018) Andújar, Carlos; Argudo, Oscar; Besora, Isaac; Brunet, Pere; Chica, Antoni; Comino Trinidad, Marc; García-Fernández, Ignacio and Ureña, Carlos
    Structure-from-motion along with multi-view stereo techniques jointly allow for the inexpensive scanning of 3D objects (e.g. buildings) using just a collection of images taken from commodity cameras. Despite major advances in these fields, a major limitation of dense reconstruction algorithms is that correct depth/normal values are not recovered on specular surfaces (e.g. windows) and parts lacking image features (e.g. flat, textureless parts of the facade). Since these reflective properties are inherent to the surface being acquired, images from different viewpoints hardly contribute to solve this problem. In this paper we present a simple method for detecting, classifying and filling non-valid data regions in depth maps produced by dense stereo algorithms. Triangles meshes reconstructed from our repaired depth maps exhibit much higher quality than those produced by state-of-the-art reconstruction algorithms like Screened Poisson-based techniques.
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    Intensity-Guided Exposure Correction for Indoor LiDAR Scans
    (The Eurographics Association, 2021) Comino Trinidad, Marc; Andújar, Carlos; Bosch, Carles; Chica, Antonio; Munoz-Pandiella, Imanol; Ortega, Lidia M. and Chica, Antonio
    Terrestrial Laser Scanners, also known as LiDAR, are often equipped with color cameras so that both infrared and RGB values are measured for each point sample. High-end scanners also provide panoramic High Dynamic Range (HDR) images. Rendering such HDR colors on conventional displays requires a tone-mapping operator, and getting a suitable exposure everywhere on the image can be challenging for 360° indoor scenes with a variety of rooms and illumination sources. In this paper we present a simple-to-implement tone mapping algorithm for HDR panoramas captured by LiDAR equipment. The key idea is to choose, on a per-pixel basis, an exposure correction factor based on the local intensity (infrared reflectivity). Since LiDAR intensity values for indoor scenes are nearly independent from the external illumination, we show that intensity-guided exposure correction often outperforms state-of-the-art tone-mapping operators on this kind of scenes.
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    Bidirectional Exploration of 3D Cultural Heritage Models and Photo Collections
    (The Eurographics Association, 2025) Borràs, Bernat; Muñoz-Pandiella, Imanol; Andújar, Carlos; Argudo, Oscar; Iparraguirre, Olatz
    Advances in 3D digitization have greatly improved the availability of high-quality cultural heritage datasets, often consisting of 3D models and collections of high-resolution photos. However, navigating these 3D datasets poses challenges for art history researchers, especially when they need to repeatedly locate points of interest, get close-up views of them, and analyze their spatial relationships. Existing applications for 3D model sharing often fail to provide a convenient interface to simultaneously explore the 3D model and associated photo collections. This paper proposes a web-based approach that combines a 3D view of the model with a 2D view of a group of photos. Designers can quickly arrange groups of images into 2D projections, and cultural heritage users can explore the 3D model and, simultaneously, the active group of images in the 2D view. Both views are interlinked, so that navigating the 3D model modifies the active photo group, and clicking an image in the 2D view moves the 3D camera to the 3D position the image was taken from. We tested our approach with a 3D dataset on medieval mural paintings. Our tests show that our method helps users quickly locate, inspect and relate different parts of the model, reducing navigation time and frustration. The source code is available at https://github.com/BernatBC/visualitzador-de-fotografies-en-3D.