Pipelined Sort-last Rendering: Scalability, Performance and Beyond

We present in this paper a theoretical and practical performance analysis of pipelined sort-last rendering for both polygonal and volume rendering. Theoretical peak performance and scalability are studied, exhibiting maximum attainable framerates of 19 fps (volume rendering with back-to-front alpha blending) and 11 fps (polygonal rendering with Z-buffer compositing) for a 1280×1024 display on a Gigabit Ethernet cluster. We show that our implementation of pipelined sort-last rendering on a 17-node PC cluster can nearly sustain these theoretical figures. We finally propose possible enhancements that would allow to go beyond the maximum theoretical limits. This paper clearly shows the potential of pipelined sort-last rendering for real-time visualization of very large models on standard PC clusters

COTS Cluster-based Sort-last Rendering: Performance Evaluation and Pipelined Implementation

Sort-last parallel rendering is an efficient technique to visualize huge datasets on COTS clusters. The dataset is subdivided and distributed across the cluster nodes. For every frame, each node renders a full resolution image of its data using its local GPU, and the images are composited together using a parallel image compositing algorithm. In this paper, we present a performance evaluation of standard sort-last parallel rendering methods and of the different improvements proposed in the literature. This evaluation is based on a detailed analysis of the different hardware and software components. We present a new implementation of sort-last rendering that fully overlaps CPU(s), GPU and network usage all along the algorithm. We present experiments on a 3 years old 32-node PC cluster and on a 1.5 years old 5-node PC cluster, both with Gigabit interconnect, showing volume rendering at respectively 13 and 31 frames per second and polygon rendering at respectively 8 and 17 frames per second on a 1024×768 render area, and we show that our implementation outperforms or equals many other implementations and specialized visualization clusters

Distributed Shared Memory for Roaming Large Volumes

We present a cluster-based volume rendering system for roaming very large volumes. This system allows to move a gigabyte-sized probe inside a total volume of several tens or hundreds of gigabytes in real-time. While the size of the probe is limited by the total amount of texture memory on the cluster, the size of the total data set has no theoretical limit. The cluster is used as a distributed graphics processing unit that both aggregates graphics power and graphics memory. A hardware-accelerated volume renderer runs in parallel on the cluster nodes and the final image compositing is implemented using a pipelined sort-last rendering algorithm. Meanwhile, volume bricking and volume paging allow efficient data caching. On each rendering node, a distributed hierarchical cache system implements a global software-based distributed shared memory on the cluster. In case of a cache miss, this system first checks page residency on the other cluster nodes instead of directly accessing local disks. Using two Gigabit Ethernet network interfaces per node, we accelerate data fetching by a factor of 4 compared to directly accessing local disks. The system also implements asynchronous disk access and texture loading, which makes it possible to overlap data loading, volume slicing and rendering for optimal volume roaming

Design and Implementation of an Immersive Geoscience Toolkit

Colloque avec actes et comité de lecture.Having a better way to represent and to interact with large geological models are topics of high interest in geoscience, and especially for oil and gas companies. We present in this paper the design and implementation of a visualization program that involves two main features. It is based on the central data model, in order to display in real time the modifications caused by the modeler. Furthermore, it benefits from the different immersive environments which give the user a much more accurate insight of the model than a regular computer screen. Then, we focus on the difficulties that come in the way of performance

Fast and Accurate Wavelet Radiosity Computations Using High-End Platforms

Colloque avec actes et comité de lecture. internationale.International audienceIn this paper, we show how to fully exploit the capabilities of high--end SGI graphics and parallel machines to perform radiosity computations on scenes made of complex shapes both quickly and accurately. Overlapping multi--processing and multi--pipeline graphics accelerations on one hand, and incorporating recent research works on wavelet radiosity on the other hand, allows radiosity to become a practical tool for interactive design

Plasma appearance and correlation between coffee and green tea metabolites in human subjects

Coffee and green tea are two of the most widely consumed hot beverages in the world. Their respective bioavailability has been studied separately, but absorption of their respective bioactive phenolics has not been compared. In a randomised cross-over design, nine healthy subjects drank instant coffee and green tea. Blood samples were collected over 12h and at 24h to assess return to baseline. After green tea consumption, (−)-epigallocatechin (EGC) was the major catechin, appearing rapidly in the plasma; (−)-EGC gallate (EGCg) and (−)-epicatechin (EC) were also present, but (−)-EC gallate and C were not detected. Dihydroferulic acid and dihydrocaffeic acid were the major metabolites that appeared after coffee consumption with a long time needed to reach maximum plasma concentration, suggesting metabolism and absorption in the colon. Other phenolic acid equivalents (caffeic acid (CA), ferulic acid (FA) and isoferulic acid (iFA)) were detected earlier, and they peaked at lower concentrations. Summations of the plasma area under the curves (AUC) for the measured metabolites showed 1·7-fold more coffee-derived phenolic acids than green tea-derived catechins (P=0·0014). Furthermore, we found a significant correlation between coffee metabolites based on AUC. Inter-individual differences were observed, but individuals with a high level of CA also showed a correspondingly high level of FA. However, no such correlation was observed between the tea catechins and coffee phenolic acids. Correlation between AUC and maximum plasma concentration was also significant for CA, FA and iFA and for EGCg. This implies that the mechanisms of absorption for these two classes of compounds are different, and that a high absorber of phenolic acids is not necessarily a high absorber of catechin

The SIB Swiss Institute of Bioinformatics' resources: focus on curated databases

The SIB Swiss Institute of Bioinformatics (www.isb-sib.ch) provides world-class bioinformatics databases, software tools, services and training to the international life science community in academia and industry. These solutions allow life scientists to turn the exponentially growing amount of data into knowledge. Here, we provide an overview of SIB's resources and competence areas, with a strong focus on curated databases and SIB's most popular and widely used resources. In particular, SIB's Bioinformatics resource portal ExPASy features over 150 resources, including UniProtKB/Swiss-Prot, ENZYME, PROSITE, neXtProt, STRING, UniCarbKB, SugarBindDB, SwissRegulon, EPD, arrayMap, Bgee, SWISS-MODEL Repository, OMA, OrthoDB and other databases, which are briefly described in this article

Early Mesozoic burst of morphological disparity in the slow-evolving coelacanth fish lineage

Since the split of the coelacanth lineage from other osteichthyans 420 million years ago, the morphological disparity of this clade has remained remarkably stable. Only few outliers with peculiar body shape stood out over the evolutionary history, but they were phylogenetically and stratigraphically independent of each other. Here, we report the discovery of a new clade of ancient latimeriid coelacanths representing a small flock of species present in the Western Tethys between 242 and 241 million years ago. Among the four species, two show highly derived anatomy. A new genus shows reversal to plesiomorphic conditions in its skull and caudal fin organisation. The new genus and its sister Foreyia have anatomical modules that moved from the general coelacanth Bauplau either in the same direction or in opposite direction that affect proportions of the body, opercle and fins. Comparisons with extant genetic models shows that changes of the regulatory network of the Hedgehog signal gene family may account for most of the altered anatomy. This unexpected, short and confined new clade represents the only known example of a burst of morphological disparity over the long history of coelacanths at a recovery period after the Permian–Triassic Mass Extinction.</p

Correlation between environment and Late Mesozoic ray-finned fish evolution

International audienceIn order to better understand the parameters that drove evolution of actinopterygian fishes from the Late Jurassic to the Late Cretaceous (this being the time of diversification of crown group teleosts, by far the dominant fish group today), we define three environmental indicators, which are detectable as concordant patterns in the geological and fossil records. These are 1) freshwater radiations, 2) vicariant events and 3) sea temperature. We mapped the indicators onto a phylogeny of the Late Jurassic–Palaeocene actinopterygian taxa, and plotted the variations against time for each of the indicators. Our results show that for several of the marine clades, diversity is positively correlated with sea temperature and for one clade negatively correlated with sea temperature. The marine radiation is very important in the mid-Cretaceous, especially in the Tethys, which may have been a centre of origin for some clades. Vicariant events occurred in both marine and freshwater groups, and are abundant during the opening of the south Atlantic in the Early Cretaceous. Freshwater radiations, forming in some cases species flocks, are especially evident in the basal Cretaceous in Asia. Although these results are affected by biases related to the fossil record and to its study, we propose that these global patterns are genuine and reflect the strong impact of the Earth system on the evolution of fishes in the Late Mesozoic

Revision of the Middle Triassic coelacanth Ticinepomis Rieppel 1980 (Actinistia, Latimeriidae) with paleobiological and paleoecological considerations

Abstract Coelacanths form today an impoverished clade of sarcopterygian fishes, which were somewhat more diverse during their evolutionary history, especially in the Triassic. Since the first description of the coelacanth Ticinepomis peyeri from the Besano Formation of the UNESCO World Heritage Site of Monte San Giorgio (Canton Ticino, Switzerland), the diversity of coelacanths in the Middle Triassic of this area of the western Paleo-Tethys has been enriched with discoveries of other fossil materials. At Monte San Giorgio, two specimens of Heptanema paradoxum and several specimens of the unusual coelacanth Rieppelia heinzfurreri, have been reported from the Meride Limestone and the Besano Formation, respectively. Another unusual coelacanth, Foreyia maxkuhni, and two specimens referred to Ticinepomis cf. T. peyeri have been described from the isochronous and paleogeographical close Prosanto Formation at the Ducanfurgga and Strel sites (near Davos, Canton Graubünden). In the framework of the revision of the coelacanth material from the Besano Formation kept in the collection of the Paläontologisches Institut und Museum der Universität Zürich (Switzerland), we reviewed the genus Ticinepomis on the basis of the holotype and four new referred specimens. Several morphological traits that were little and/or not understood in T. peyeri are here clarified. We re-evaluate the taxonomic attribution of the material of Ticinepomis cf. T. peyeri from the Prosanto Formation. Morphological characters are different enough from the type species, T. peyeri, to erect a new species, Ticinepomis ducanensis sp. nov., which is shown to be also present in the Besano Formation of Monte San Giorgio, where it is represented by fragmentary bone elements. The recognition of a new coelacanth species indicates that the diversity of this slow-evolving lineage was particularly high in this part of the Western Tethys during the Middle Triassic, especially between 242 and 240 million years ago