Efficient conservative visibility culling using theprioritized-layered projection algorithm

We propose a novel conservative visibility culling technique based on the Prioritized-Layered Projection (PLP) algorithm. PLP is a time-critical rendering technique that computes, for a given viewpoint, a partially correct image by rendering only a subset of the geometric primitives, those that PLP determines to be most likely visible. Our new algorithm builds on PLP and provides an efficient way of finding the remaining visible primitives. We do this by adding a second phase to PLP which uses image-space techniques for determining the visibility status of the remaining geometry. Another contribution of our work is to show how to efficiently implement such image-space visibility queries using currently available OpenGL hardware and extensions. We report on the implementation of our techniques on several graphics architectures, analyze their complexity, and discuss a possible hardware extension that has the potential to further increase performance     

New 2-D dosimetric technique for radiotherapy based on planar thermoluminescent detectors

At the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ) in Kraków, a two-dimensional (2-D) thermoluminescence (TL) dosimetry system was developed within the MAESTRO (Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology) 6 Framework Programme and tested by evaluating 2-D dose distributions around radioactive sources. A thermoluminescent detector (TLD) foil was developed, of thickness 0.3 mm and diameter 60 mm, containing a mixture of highly sensitive LiF:Mg,Cu,P powder and Ethylene TetraFluoroEthylene (ETFE) polymer. Foil detectors were irradiated with (226)Ra brachytherapy sources and a (90)Sr/(90)Y source. 2-D dose distributions were evaluated using a prototype planar (diameter 60 mm) reader, equipped with a 12 bit Charge Coupled Devices (CCD) PCO AG camera, with a resolution of 640 x 480 pixels. The new detectors, showing a spatial resolution better than 0.5 mm and a measurable dose range typical for radiotherapy, can find many applications in clinical dosimetry. Another technology applicable to clinical dosimetry, also developed at IFJ, is the Si microstrip detector of size 95 x 95 mm(2), which may be used to evaluate the dose distribution with a spatial resolution of 120 microm along one direction, in real-time mode. The microstrip and TLD technology will be further improved, especially to develop detectors of larger area, and to make them applicable to some advanced radiotherapy modalities, such as intensity modulated radiotherapy (IMRT) or proton radiotherapy.     

The prioritized-layered projection algorithm for visible setestimation

Prioritized-Layered Projection (PLP) is a technique for fast rendering of high depth complexity scenes. It works by estimating the visible polygons of a scene from a given viewpoint incrementally, one primitive at a time. It is not a conservative technique, instead PLP is suitable for the computation of partially correct images for use as part of time-critical rendering systems. From a very high level, PLP amounts to a modification of a simple view-frustum culling algorithm, however, it requires the computation of a special occupancy-based tessellation and the assignment to each cell of the tessellation a solidity value, which is used to compute a special ordering on how primitives get projected. The authors detail the PLP algorithm, its main components, and implementation. They also provide experimental evidence of its performance, including results on two types of spatial tessellation (using octree- and Delaunay-based tessellations), and several datasets. They also discuss several extensions of their technique     

Directional Discretized Occluders for Accelerated Occlusion Culling

We present a technique for accelerating the rendering of high depth-complexity scenes. In a preprocessing stage, we approximate the input model with a hierarchical data structure and compute simple view-dependent polygonal occluders to replace the complex input geometry in subsequent visibility queries. When the user is inspecting and visualizing the input model, the computed occluders are used to avoid rendering geometry which cannot be seen. Our method has several advantages which allow it to perform conservative visibility queries efficiently and it does not require any special graphics hardware. The preprocessing step of our approach can also be used within the framework of other visibility culling methods which need to pre-select or pre-render occluders. In this paper, we describe our technique and its implementation in detail, and provide experimental evidence of its performance. In addition, we briefly discuss possible extensions of our algorithm.     

Chitosan/nanocellulose-based bionanocomposite films for controlled betamethasone and silver sulfadiazine delivery

Bionanocomposite films based on chitosan and nanocellulose (nanocrystals or nanofibrils) have gained considerable attention for biomedical applications, especially for wound dressings. However, the development of these films as controlled drug release dressings is still under-exploited. Therefore, this work aimed to design chitosan/nanocellulose-based bionanocomposite films, loaded by betamethasone or silver sulfadiazine, as functional dressings. The films were obtained by solvent casting and characterized by physicochemical, mechanical, barrier properties, in vitro drug release, and antimicrobial activity. The nanocellulose type, physical state, and content caused influence on the film's properties providing different physical, barrier, and drug release profiles. They are semi-occlusive and mechanically resistant; the drug release is controlled, and possesses antimicrobial activity. In conclusion, the developed biodegradable bionanocomposite films are promising as active dressings for controlled drug delivery in the wound site and have specific applications according to their features to treat inflamed and purulent wounds, non-infectious dry wounds, and infectious wounds.     

Deep view: high-resolution reality

We have designed the Deep View visualization system, which consists of a Linux cluster that performs computations to produce 3D geometry, renders the geometry to produce 2D pixels, and then transfers the pixels to be displayed on the T221 display (or video wall). We accelerate the pixel transfer operations using IBM's Scalable Graphics Engine (SGE). We drive high-resolution displays at interactive frame rates using our cluster and the SGE. The SGE is a network-attached frame buffer capable of double buffering up to 16 million pixels. It routes incoming pixels from multiple sources to the appropriate locations in its frame buffer and then transfers the composited result to the T221 display using digital video interface (DVI) output. In total, the SGE can accept up to 16 input links and can drive as many as eight synchronized DVI outputs. In addition, it can time interleave image pairs from its frame buffer to effect time-division stereo. In the current Deep View configuration, the rendered pixels are sent by each node in the cluster to the SGE over a Gigabit Ethernet link, and we use four of the synchronized DVI outputs to drive the T221 at full resolution