Cylindrical and Toroidal Parameterizations Without Vertex Seams

A simple rendering method to avoid vertex seams in cylindrical and toroidal UV mappings used for texture mapping is presented. (A vertex seam is a vertex duplication of a polygonal mesh with different texture coordinates assigned to the two geometrically coinciding copies.) As a result, the method leads to simpler, leaner, replication-free data structures. Is also allows for a higher degree of proceduralism in generation of texture coordinates. The method is general, trivial to implement (exhaustive pseudocode is provided), very low in cost on resources (with a virtually null impact on performance), and it leverages only basic mechanisms widely available in most GPU implementations. An open-source implementation is available online

A quadrilateral rendering primitive

The only surface primitives that are supported by common graphics hardware are triangles and more complex shapes have to be triangulated before being sent to the rasterizer. Even quadrilaterals, which are frequently used in many applications, are rendered as a pair of triangles after splitting them along either diagonal. This creates an undesirable C1 -discontinuity that is visible in the shading or texture signal. We propose a new method that overcomes this drawback and is designed to be implemented in hardware as a new rasterizer. It processes a potentially non-planar quadrilateral directly without any splitting and interpolates attributes smoothly inside the quadrilateral. This interpolation is based on a recent generalization of barycentric coordinates that we adapted to handle perspective correction and situations in which a quadrilateral is partially behind the point of view.The only surface primitives that are supported by common graphics hardware are triangles and more complex shapes have to be triangulated before being sent to the rasterizer. Even quadrilaterals, which are frequently used in many applications, are rendered as a pair of triangles after splitting them along either diagonal. This creates an undesirable C1-discontinuity that is visible in the shading or texture signal. We propose a new method that overcomes this drawback and is designed to be implemented in hardware as a new rasterizer. It processes a potentially non-planar quadrilateral directly without any splitting and interpolates attributes smoothly inside the quadrilateral. This interpolation is based on a recent generalization of barycentric coordinates that we adapted to handle perspective correction and situations in which a quadrilateral is partially behind the point of view. \ua9 The Eurographics Association 2004

Pinchmaps: textures with customizable discontinuities

We introduce a new texture representation that combines standard sampling, to be bilinearly interpolated in smoothly varying regions, with customizable discontinuities, to model sharp boundaries between these regions. The structure consists of a standard signal texture, plus a second texture we call pinchmap, which encodes discontinuities along generally curved lines; at rendering time the fragment processor efficiently decodes this structure with a single access to each texture. We also present a fully automatic way to compute a pinchmap and signal texture pair, starting from an original high resolution image. The final result on the screen is a comparable visual quality for a fraction of the texture storage and with a negligible impact on performance

QuteMol

QuteMol is an open source (GPL), interactive, high quality molecular visualization system. QuteMol exploits the current GPU capabilites through OpenGL shaders to offers an array of innovative visual effects. QuteMol visualization techniques are aimed at improving clarity and an easier understanding of the 3D shape and structure of large molecules or complex proteins. * Real Time Ambient Occlusion * Depth Aware Silhouette Enhancement * Ball and Sticks, Space-Fill and Liquorice visualization modes * High resolution antialiased snapshots for creating publication quality renderings * Automatic generation of animated gifs of rotating molecules for web pages animations * Real-time rendering of large molecules and protein (>100k atoms) * Standard PDB input * Quick installers for Win and Mac OS X (intel) (new!) * Support as a plugins of the NanoEngineer-1 the modeling and simulation program for nano-composites (new!

Visibility based methods and assessment for detail-recovery

In this paper we propose a new method for the creation of normal maps for recovering the detail on simpli\ufb01ed meshes and a set of objective techniques to metrically evaluate the quality of different recovering techniques. The proposed techniques, that automatically produces a normal-map texture for a simple 3D model that \u201cimitates\u201d the high frequency detail originally present in a second, much higher resolution one, is based on the computation of per-texel visibility and self-occlusion information. This information is used to de\ufb01ne a point-to-point correspondence between simpli\ufb01ed and hi-res meshes. Moreover, we introduce a number of criteria for measuring the quality (visual or otherwise) of a given mapping method, and provide ef\ufb01cient algorithms to implement them. Lastly, we apply them to rate different mapping methods, including the widely used ones and the new one proposed here

Browsing Large Image Datasets through Voronoi Diagrams

Conventional browsing of image collections use mechanisms such as thumbnails arranged on a regular grid or on a line, often mounted over a scrollable panel. However, this approach does not scale well with the size of the datasets (number of images). In this paper, we propose a new thumbnail-based interface to browse large collections of images. Our approach is based on weighted centroidal anisotropic Voronoi diagrams. A dynamically changing subset of images is represented by thumbnails and shown on the screen. Thumbnails are shaped like general polygons, to better cover screen space, while still reflecting the original aspect ratios or orientation of the represented images. During the browsing process, thumbnails are dynamically rearranged, reshaped and rescaled. The objective is to devote more screen space (more numerous and larger thumbnails) to the parts of the dataset closer to the current region of interest, and progressively lesser away from it, while still making the dataset visible as a whole. During the entire process, temporal coherence is always maintained. GPU implementation easily guarantees the frame rates needed for fully smooth interactivity

3D Acquisition of Mirroring Objects using Striped Patterns

Objects with mirroring optical characteristics are left out of the scope of most 3D scanning methods. We present here a new automatic acquisition approach, shape-from-distortion, that focuses on that category of objects, requires only a still camera and a color monitor, and produces range scans (plus a normal and a reflectance map) of the target. Our technique consists of two steps: first, an improved environment matte is captured for the mirroring object, using the interference of patterns with different frequencies to obtain sub-pixel accuracy. Then, the matte is converted into a normal and a depth map by exploiting the self-coherence of a surface when integrating the normal map along different paths. The results show very high accuracy, capturing even smallest surface details. The acquired depth maps can be further processed using standard techniques to produce a complete 3D mesh of the object

Almost Isometric Mesh Parameterization through Abstract Domains

In this paper, we propose a robust, automatic technique to build a global hi-quality parameterization of a two-manifold triangular mesh. An adaptively chosen 2D domain of the parameterization is built as part of the process. The produced parameterization exhibits very low isometric distortion, because it is globally optimized to preserve both areas and angles. The domain is a collection of equilateral triangular 2D regions enriched with explicit adjacency relationships (it is abstract in the sense that no 3D embedding is necessary). It is tailored to minimize isometric distortion, resulting in excellent parameterization qualities, even when meshes with complex shape and topology are mapped into domains composed of a small number of large continuous regions. Moreover, this domain is, in turn, remapped into a collection of 2D square regions, unlocking many advantages found in quad-based domains (e. g., ease of packing). The technique is tested on a variety of cases, including challenging ones, and compares very favorably with known approaches. An open-source implementation is made available

Joint Interactive Visualization of 3D Models and Pictures in Walkable Scenes

The 3D digitalization of buildings, urban scenes, and the like is now a mature technology. Highly complex, densely sampled, reasonably accurate 3D models can be obtained by range-scanners and even image-based reconstruction methods from dense image collections. Acquisition of naked geometry is not enough in Cultural Heritage applications, because the surface colors (e.g. pictorial data) are clearly of central importance. Moreover, the 3D geometry cannot be expected to be complete, lacking context, parts made of materials like glass and metal, difficult to reach surfaces, etc. Easily captured photographs are the natural source of the appearance data missing in the 3D geometry. In spite of the recent availability of reliable technologies to align 2D images on 3D data, the two sides of the dataset are not easy to combine satisfactorily in a visualization. Texture mapping techniques, perhaps the most obvious candidate for the task, assume strict content consistency (3D to 2D, and 2D to 2D) which these datasets do not and should not exhibit (the advantage of pictures consisting in their ability to feature details, lighting conditions, non-persistent items, etc. which are absent in the 3D models or in the other pictures). In this work, we present a simple but effective technique to jointly and interactively visualize 2D and 3D data of this kind. This technique is used within PhotoCloud [IV12], a flexible opensource tool which is being designed to browse, navigate, and visualize large, remotely stored 3D-2D datasets, and which emphasizes scalability, usability, and ability to cope with heterogeneous data from various sources

Real Time, Accurate, Multi-Featured Rendering of Bump Mapped Surfaces

We present a new technique to render in real time objects which have part of their high frequency geometric detail encoded in bump maps. It is based on the quantization of normal-maps, and achieves excellent result both in rendering time and rendering quality, with respect to other alternative methods. The method proposed also allows to add many interesting visual effects, even for object with large bumb maps, including non-photorealistic rendering, chrome effects, shading under multiple lights, rendering of different materials within a single object, specular reflections and others. Moreover, the implementation of the method is not complex and can be eased by software reuse