Rendering Deformable Surface Reflectance Fields

Animation of photorealistic computer graphics models is an important goal for many applications. Image-based modeling has emerged as a promising approach to capture and visualize real-world objects. Animating image-based models, however, is still a largely unsolved problem. In this paper, we extend a popular image-based representation called surface reflectance field to animate and render deformable real-world objects under arbitrary illumination. Deforming the surface reflectance field is achieved by modifying the underlying impostor geometry. We augment the impostor by a local parameterization that allows the correct evaluation of acquired reflectance images, preserving the original light model on the deformed surface. We present a deferred shading scheme to handle the increased amount of data involved in shading the deformable surface reflectance field. We show animations of various objects that were acquired with 3D photography.Engineering and Applied Science

Milk production from grazed pasture in mountainous regions of Austria - impact of calving season

The influence of calving season on milk yield, lactation length, composition of the diet, reproduction and nutrient supply for pasture-based systems in a mountainous region of Austria was examined with thirty-three dairy cows on an organic farm. Three groups of cows with a mean calving date of 17 November (group 1), 25 December (group 2) and 20 February (group 3) were compared. During winter periods the cows were housed and fed with grass silage, hay and a restrictive amount of concentrate. Cows were on pasture for 202 days in 2008 and 203 days in 2009 (177 day and night grazing days). The pasture area was continuously grazed at an average sward height of 4.7 cm. Calving in February (group 3) significantly depressed lactation length and milk-fat yield and tended to decrease energy-corrected-milk yield. From group 1 to 3 the amount of concentrate fed per cow decreased from 669 to 373 kg DM y-1 and the grazed pasture proportion increased from 43 to 50% of total feeding ration per year. Calving date had no effects on reproductive performance and frequency of veterinary treatments. However, at the beginning of the grazing season live weight loss and contents of βHBA, FFA and AST were highest in blood samples of group 3

Trends in precipitation measurement and climate model data and their influence on the assessment of urban systems

Rainfall statistics are composed based on data gained by precipitation measurements and from climate models. These statistics are carried out for both periods in the past and the future. When analysing the time series, different trends can be seen in the measured data of the past and the model data for future periods. Influences on the statistically determined precipitation amounts caused by changes can be neglected for past periods. However, significant increases of the statistical precipitation amounts can be observed for the future. Here a pragmatic approach is presented, showing how to consider possible increases in the statistical precipitation amounts – due to the climate change signal – in the dimensioning of water management systems

Surfels: Surface Elements as Rendering Primitives

Surface elements (surfels) are a powerful paradigm to efficiently render complex geometric objects at interactive frame rates. Unlike classical surface discretizations, i.e., triangles or quadrilateral meshes, surfels are point primitives without explicit connectivity. Surfel attributes comprise depth, texture color, normal, and others. As a pre-process, an octree-based surfel representation of a geometric object is computed. During sampling, surfel positions and normals are optionally perturbed, and different levels of texture colors are prefiltered and stored per surfel. During rendering, a hierarchical forward warping algorithm projects surfels to a z-buffer. A novel method called visibility splatting determines visible surfels and holes in the z-buffer. Visible surfels are shaded using texture filtering, Phong illumination, and environment mapping using per-surfel normals. Several methods of image reconstruction, including supersampling, offer flexible speed-quality tradeoffs. Due to the simplicity of the operations, the surfel rendering pipeline is amenable for hardware implementation. Surfel objects offer complex shape, low rendering cost and high image quality, which makes them specifically suited for low-cost, real-time graphics, such as games.Engineering and Applied Science

EWA Splatting

In this paper, we present a framework for high quality splatting based on elliptical Gaussian kernels. To avoid aliasing artifacts, we introduce the concept of a resampling filter, combining a reconstruction kernel with a low-pass filter. Because of the similarity to Heckbert's EWA (elliptical weighted average) filter for texture mapping, we call our technique EWA splatting. Our framework allows us to derive EWA splat primitives for volume data and for point-sampled surface data. It provides high image quality without aliasing artifacts or excessive blurring for volume data and, additionally, features anisotropic texture filtering for point-sampled surfaces. It also handles nonspherical volume kernels efficiently; hence, it is suitable for regular, rectilinear, and irregular volume datasets. Moreover, our framework introduces a novel approach to compute the footprint function, facilitating efficient perspective projection of arbitrary elliptical kernels at very little additional cost. Finally, we show that EWA volume reconstruction kernels can be reduced to surface reconstruction kernels. This makes our splat primitive universal in rendering surface and volume data.Engineering and Applied Science

Surface Splatting

Modern laser range and optical scanners need rendering techniques that can handle millions of points with high resolution textures. This paper describes a point rendering and texture filtering technique called surface splatting which directly renders opaque and transparent surfaces from point clouds without connectivity. It is based on a novel screen space formulation of the Elliptical Weighted Average (EWA) filter. Our rigorous mathematical analysis extends the texture resampling framework of Heckbert to irregularly spaced point samples. To render the points, we develop a surface splat primitive that implements the screen space EWA filter. Moreover, we show how to optimally sample image and procedural textures to irregular point data during pre-processing. We also compare the optimal algorithm with a more efficient view-independent EWA pre-filter. Surface splatting makes the benefits of EWA texture filtering available to point-based rendering. It provides high quality anisotropic texture filtering, hidden surface removal, edge anti-aliasing, and order-independent transparency.Engineering and Applied Science

Unconstrained Free-Viewpoint Video Coding

In this paper, we present a coding framework addressing image-space compression for free-viewpoint video. Our framework is based on time-varying 3D point samples which represent real-world objects. The 3D point samples are obtained after a geometrical reconstruction from multiple pre-recorded video sequences and thus allow for arbitrary viewpoints during playback. The encoding of the data is performed as an off-line process and is not time-critical. The decoding however, must support for real-time rendering of the dynamic 3D data. We introduce a compression framework which encodes multiple point attributes like depth and color into progressive streams. The reference data structure is aligned on the original camera input images and thus enables for easy view-dependent decoding. A novel differential coding approach permits random access in constant time throughout the entire data set and thus enables arbitrary viewpoint trajectories in both time and space.Engineering and Applied Science

Vollweidehaltung von Milchkühen im Berggebiet – Einfluss des Abkalbezeitpunktes auf Rationszusammensetzung, Leistungs- und Gesundheitsparameter

Bei „Low-Cost“-Vollweidehaltung von Milchkühen wird eine optimale Verwertung des Weidefutters angestrebt. Ein wichtiges Managementkriterium ist dabei die Abstimmung des Abkalbezeitpunktes auf die Vegetationsperiode. In der vorliegenden Untersuchung wurden die Effekte des Abkalbezeitunktes auf die weidebasierte Milchproduktion im Berggebiet untersucht. Es wurde dazu 33 Milchkühe der Versuchsherde des Bio-Lehr- und Forschungbetriebs Moarhof drei Versuchsgruppen zugeteilt. Das durchschnittliche Abkalbedatum der Gruppe 1 war der 17. November, der Gruppe 2 der 25. Dezember und der Gruppe 3 der 20. Februar. In der Stallfütterungsperiode erhielten die Tiere eine Grünlandration aus Heu und Grassilage sowie eine milchleistungsabhängige Kraftfutterergänzung. Die Tiere wurden von Anfang April bis Ende Oktober 2008 bzw. 2009 über 202 bzw. 203 Tage auf einer Kurzrasenweide gehalten, wovon 177 Tage auf Tag- und Nachtweide (Vollweide) entfielen. In der Vollweidezeit erhielten Kühe unter 28 kg Tagesmilchleistung kein Kraftfutter und über einer Milchleistung von 32 kg max. 2 kg FM Kraftfutter als Ergänzung zu 1,5 kg FM Heu und Weidefutter. Der Energiegehalt der Grassilage bzw. des Heus lagen bei 5,8 (± 0,2) bzw. 5,4 (± 0,3) MJ NEL und der Rohproteingehalt bei knapp15 (± 1,5) bzw. 12 % (± 0,5) je kg T. Für die Kraftfuttermischungen ergab sich ein Energiegehalt von 7,8 MJ NEL und ein Rohproteingehalt von 13 % (± 0,3) je kg T. Die Weidefutterproben wiesen in den Versuchsjahren im Mittel einen Energiegehalt von 6,4 (± 0,33) MJ NEL und einen Rohproteingehalt von knapp 22 % (± 3) je kg Trockenmasse auf. Die durchschnittliche Laktationsdauer (299 auf 284 Tage) und die Milchfettmenge ging signifikant und die energiekorrigierte Milchleistung tendenziell von Gruppe 1 bis Gruppe 3 zurück. Die Milchleistungen der Gruppen 1–3 lagen pro Laktation bei 6.300, 5.974 und 5.449 kg ECM, 6.360, 6.135 und 5.727 kg Milch, 261, 245 und 217 kg Fett bzw. 200, 189 und 178 kg Eiweiß. Im Gegensatz zu Gruppe 3 zeigten die Tiere der Gruppen 1 und 2 zu Weidebeginn einen zweiten Milchleistungsanstieg. Der Kraftfutteraufwand pro Kuh verringerte sich signifikant von Gruppe 1 bis Gruppe 3 von 11 % (669 kg T/Jahr bzw. 652 kg T/Laktation) auf 6 % (373 kg T/Jahr bzw. 349 kg T/Laktation) an der Jahresration und der Weidefutteranteil stieg von 43 % auf 50 % der Gesamt-T-Aufnahme pro Jahr an. Bei den Tieren der Gruppe 3 wurde zu Laktationsbeginn die stärkste Lebendmasse- und BCS-Abnahme festgestellt. Die Fruchtbarkeitsergebnisse sowie die Anzahl an tierärztlichen Behandlungen wurden vom Abkalbezeitpunkt nicht signifikant beeinflusst. Die höchsten β-HB-, FFS- und Aspartat-Amino-Transferase-Gehalte wurden zu diesem Zeitpunkt in Gruppe 3 festgestellt

Capture and Modeling of Non-Linear Heterogeneous Soft Tissue

This paper introduces a data-driven representation and modeling technique for simulating non-linear heterogeneous soft tissue. It simplifies the construction of convincing deformable models by avoiding complex selection and tuning of physical material parameters, yet retaining the richness of non-linear heterogeneous behavior. We acquire a set of example deformations of a real object, and represent each of them as a spatially varying stress-strain relationship in a finite-element model. We then model the material by non-linear interpolation of these stress-strain relationships in strain-space. Our method relies on a simple-to-build capture system and an efficient run-time simulation algorithm based on incremental loading, making it suitable for interactive computer graphics applications. We present the results of our approach for several non-linear materials and biological soft tissue, with accurate agreement of our model to the measured data.Engineering and Applied Science