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A directional occlusion shading model for interactive direct volume rendering

A directional occlusion shading model for interactive direct volume rendering

Ritschel [Rit07] considers the illumination of a volume data set under distant spherical illumination represented by an environment map. A visibility function is computed by integrating the transmittance along hundreds of rays ema- nating from each voxel using spatial undersampling and an adaptive traversal of a hierarchical data structure. A spher- ical harmonics decomposition of both the visibility func- tion and the environment maps allows efficient storage and evaluation of low frequency indirect illumination values dur- ing direct volume rendering. Changing the transfer function requires a few seconds for recomputation of the visibility function. Rezk-Salama et al. [RS07] use GPUs to accelerate Monte-Carlo volume ray-casting to render isosurfaces with high-quality scattering, AO and refraction effects.
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Occlusion-based Direct Volume Rendering for Computed Tomography Image

Occlusion-based Direct Volume Rendering for Computed Tomography Image

Direct volume rendering (DVR) is an important 3D visualization method for medical images as it depicts the full volumetric data. However, because DVR renders the whole volume, regions of interests (ROIs) such as a tumor that are embedded within the volume maybe occluded from view. Thus, conventional 2D cross-sectional views are still widely used, while the advantages of the DVR are often neglected. In this study, we propose a new visualization algorithm where we augment the 2D slice of interest (SOI) from an image volume with volumetric information derived from the DVR of the same volume. Our occlusion-based DVR augmentation for SOI (ODAS) uses the occlusion information derived from the voxels in front of the SOI to calculate a depth parameter that controls the amount of DVR visibility which is used to provide 3D spatial cues while not impairing the visibility of the SOI. We outline the capabilities of our ODAS and through a variety of computer tomography (CT) medical image examples, compare it to a conventional fusion of the SOI and the clipped DVR.
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Interactive Transfer Function Specification for Direct Volume Rendering of Disparate Volumes

Interactive Transfer Function Specification for Direct Volume Rendering of Disparate Volumes

As an example, consider the ubiquitous Utah Torso dataset—an un- structured grid containing simulated electric potential in the human torso. In our example, we use a version of the dataset consisting of about 50 thousand tetrahedra and 360 floating point time steps of a rotating dipole that emphasizes the simulation results. Figure 1 illus- trates several visualizations of this data through direct volume render- ing. There are several issues that are encountered when attempting to explore this data using transfer functions. First, for each time step of the data, the scalars in the volume are concentrated in one peak in the histogram (ie., 83% of the scalars fall into 1% of the scalar range). Thus, with traditional specification tools such as a polyline defined over the histogram, feature finding may be difficult because much of
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Direct volume rendering of unstructured tetrahedral meshes using CUDA and OpenMP

Direct volume rendering of unstructured tetrahedral meshes using CUDA and OpenMP

Direct volume rendering of unstructured tetrahedral meshes 335 Processing hash blocks Apart from GPU-specific optimizations, this step is similar to the calculation of intersection effects in the CPU version of the algorithm. It starts by copying the intersection records for the current hash block to the GPU. Each thread is assigned an intersection record and responsible for producing the corresponding intersection effect data. Execution flows are mostly uniform. Continuous threads are assigned to process contiguous intersection records; thus, memory accesses are also uniform for some parts. However, the tetrahedra contain references to vertices, which are not contiguous, and accesses to the vertices cannot be made uniform. However, for repeated access to nonuniform data, the algorithm uses shared memory to store the data temporarily, which makes the subsequent memory accesses uniform and much faster. This function is launched with a grid of 1024 blocks; because of the size dif- ference of the shared memory between devices, those with a computing capability of 2.0 or higher are launched with 192 threads per block and others use 64 threads per block.
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Using Photorealistic RenderMan for High-Quality Direct Volume Rendering

Using Photorealistic RenderMan for High-Quality Direct Volume Rendering

Motion blur can be easily applied to any volume using RenderMan. This effect introduces another aspect of realism, which is traditionally not applied to volume datasets. Using RenderMan’s unique set of API calls, it is simple for the user to create an animated sequence of a volume using the same properties as a live-action camera. Using an arbitrary time scale (user defined), specify when the camera should open and close its shutter. Depending on the transformations applied during these shutter intervals RenderMan will automatically produce the correct, realistic effect. Figure 5 shows an example of motion blur applied to a volume dataset.
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Automatic transfer function generation and extinction-based approaches in direct volume visualization

Automatic transfer function generation and extinction-based approaches in direct volume visualization

Using per-pixel post-classification and post-shading for high quality rendering, compositing and blending become crucial from a performance point of view, es- pecially when the number of sheets or layers rises. It gets even worse if any kind of z-supersampling as in typical sheet based splatting is used to better approximate the volume rendering integral. Let us define the grid resolution of the volume be- ing 1.0 and the distance between two sheets as 0.5. This effectively doubles the required amount of compositing operations but produces a higher quality image through a closer approximation of the volume rendering integral, particularly for low-resolution volumes. Huang et al. demonstrate this in their OpenSplat frame- work [Huang et al., 2000]. The compositing performance is basically independent from the effective number of voxels or splats as long as no special optimizations are made. Assuming classification and shading is done in a fragment shader, Neo- phytou et al. [Neophytou and Mueller, 2005] show how special OpenGL exten- sions can be used to optimize performance. Early z-culling and depth-bounds test extensions allow dropping of fragments that are not affected during splatting or which are already opaque in a front-to-back traversal. As we use a different ex- tinction model, we cannot use the default OpenGL blending. Thus we compute blending within the fragment shader where classification and lighting takes place, and subsequently can take advantage from the same optimizations.
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Semi-automatic transfer function generation for non-domain specific direct volume rendering

Semi-automatic transfer function generation for non-domain specific direct volume rendering

Figure 30 (a) shows that the method proposed is capable ofsemi-automatically determining a transfer function that clearly shows all material boundaries within the tooth such that opaci[r]

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Lighting Transfer Functions for Direct Volume Rendering

Lighting Transfer Functions for Direct Volume Rendering

ent, diffuse and specular lighting coefficients respectively. The two samples read along the gradient direction are well-suited inputs for our lighting transfer functions since they provide an indi- cation of whether a material boundary occurs at a given sample and which materials exist on each side of that boundary. For example, if the two samples have the same value, then the center sample po- sition is likely to be in a homogeneous region. Furthermore, if the scalar values above and below the current sample belong to two dif- ferent materials, then the sample is likely at a material boundary. In- tuition as to why this approach works can be gained by further con- sidering the nature of the 2D histogram material boundary arches described by Kindlmann and Weinstein. In their work, they define material boundaries as the finitely thin transitional regions between homogeneous materials and explain that due to the band-limited nature of most data acquisition systems, a reconstructed volume will always contain a degree of blurring. They demonstrate that if a volume is reconstructed with a Gaussian reconstruction ker- nel, the transitions between idealized homogeneous regions have highest gradient values at the center of the boundary transition and diminish to zero moving away from the boundary. They illustrate this is true in practice with a variety of data sets that have 2D joint scalar/gradient magnitude histograms containing distinct arches be- tween scalar values corresponding to homogeneous regions. For a boundary between two materials, an arch starts with reduced gra- dient magnitude in a homogeneous region, increases to a higher gradient magnitude between the two materials, and then recedes moving toward the other homogeneous region.
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Segmentation Assisted Object Distinction For Direct

Volume Rendering

Segmentation Assisted Object Distinction For Direct Volume Rendering

Visual properties (ex. Color) are then assigned to geometrical objects in order to fabricate an image. Volume rendering technique is yet another example which uses th[r]

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Enhancing real time focus and context direct volume rendering

Enhancing real time focus and context direct volume rendering

This constant sampling rate is a reasonable assumption for slice based rendering but makes pre-integrated rendering unachievable in real-time for adaptive sampling techniques such as tho[r]

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The Direct Marketing Association s (DMA) Power of Direct

The Direct Marketing Association s (DMA) Power of Direct

MANAGE YOUR METRICS. Segregate your mail streams by business unit and type of mail so the results of one don’t adversely affect another, and you can cleanly see the perfor- mance of each. Establish trend lines for each mail stream, and seek to isolate and address the causes for deliverability differ- ences, such as targeting criteria, content, list management and other practices. Examine your delivery results on each mailing and drilldown into meaningful positive or negative variations from your trend line to replicate or avoid those results in the future. In short, treat deliverability as you do other aspects of direct marketing: Make it a cumulative learning experience and get progressively better at it.
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Direct Energy

Direct Energy

While a few books on direct energy conversion exist, there are few things which set this book apart. First, many of the books on direct en- ergy conversion, including [3] and [4], are written at the graduate level while this book is aimed at a more general audience. This book is used for the course Direct Energy Conversion taught at Trine University, which is a junior undergraduate level course for electrical engineers. This book is not intended only for electrical engineering students. It is also aimed at researchers who are interested in how energy conversion is studied by scientists and engineers in other disciplines. The idea of energy conversion is fundamental to physics, chemistry, mechanical engineering, and multiple other disciplines. This book discusses fundamental physics behind energy conversion processes, introduces terminology used, and relates concepts of material science used for building devices. The chapters were written so that someone who is not an antenna designer, for example, can read the relevant chapter as an introduction and gain insights into some of the ter- minology and key concepts used by electromagnetics researchers. Second, a number of good books on the topic, including [3] and [5] were written decades ago. The concepts of these books remain relevant, and these books often predicted which technologies would be of interest. However, there is a need for a book which discusses the most accessible and commonplace direct energy conversion technologies in use today. Additionally, many of these classic texts are out of print, and contemporary texts are needed.
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Direct Aeroacoustic Simulation with Volume Penalization Method

Direct Aeroacoustic Simulation with Volume Penalization Method

Abstract. Flow and acoustic fields around a circular cylinder and a cascade of flat plates are clarified by direct simulations with a volume penalization method, which is a useful method to predict flow and acoustic fields around a complex geometry in a flow. The predicted results are compared with our experimental results or those of literatures. It is also clarified that the acoustic resonance occurs between the plates for a cascade of flat plates. The phase-averaged predicted flow fields present that the vortices shed from neighboring plates is synchronized in an anti-phase mode. As a result, the intense standing waves are generated between plates.
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Evaluation of the rabbit liver by direct portography and contrast-enhanced computed tomography: anatomical variations of the portal system and hepatic volume quantification

Evaluation of the rabbit liver by direct portography and contrast-enhanced computed tomography: anatomical variations of the portal system and hepatic volume quantification

All applicable institutional and/or national guidelines for the care and use of animals were followed. Forty-six New Zealand white female rabbits weighing around 3 kg (range 2.68 − 3.55 kg) were included. This is an investigation in the context of an already established experimental study planned for other purposes. All rabbits first underwent basal CECT followed by direct portography.

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Direct Connection to IT Systems. Direct Connection to IT Systems

Direct Connection to IT Systems. Direct Connection to IT Systems

MESInterface IT Production and quality management information Power consumption information Equipment operational status information Message communication SQL communication TCP/IP, [r]

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Direct marketing

Direct marketing

The title of this paperwork alone defines that the intention was to explane the theoretical aspects of the direct marketing and to show the applications of this marketing strategy on some examples. The teoretical part of this thesis tries to define what direct marketing is, which are the fundamental goals, functions, strategy and elements of direct marketing which lead to success. The practical part of this paperwork showes the influence of direct marketing on the actual results of following three companies: Studio Moderna d.o.o., dm- drogerie markt d.o.o. and Muller d.o.o. This three companies are examples of big companies thet have long tradition on the market and that use different marketing strategies in their work. Each of them use different approach to the consumers. Our intention was to show the influence of marketing strategy on their every day sales. The final part of this paperwork is the scientific resurch that was conducted on a samples of 60 students and the two companies (dm - drogerie markt d.o.o. and Muller d.o.o.) that are the main competiturs in the same branch of sales. The research was conducted in order to define and declare how the marketing activities of the direct marketing influence on the results of the both companies, that are the main competitors, with long tradition in sales in the same branch. The results of the reseach have shown that the marketing activities of the direct marketing have a small influence on the results of these companies, but even a small influence can be positive for company that knows how to use it.
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IS IT DIRECT SELLING A TYPE OF DIRECT MARKETING? ARGUMENTS.

IS IT DIRECT SELLING A TYPE OF DIRECT MARKETING? ARGUMENTS.

“Today it is not enough anymore to talk about direct marketing but about customer relationship marketing. The centralized data base became the data warehouse. Nevertheless, the principles didn’t change that much” (Thomas and Housden, 2002, p. 135). Information technology has enabled the storage and management of customer information, building more efficient way for marketing and for creating and managing relationships between the buyer and the seller. From this reason, there are specialists that identify direct marketing with relational marketing (Lee and Johnson, 2005).
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The Effectiveness of Mental Training of Direct and Non-Direct  learning backstroke

The Effectiveness of Mental Training of Direct and Non-Direct learning backstroke

Direct training exceeded significantly in the swim performance ,these results achieved the first hypothesis of this study .The comparable impacts of direct training may be attributed to its arrangement and organized contents, and the best manner of students effort d distribution in addition to utilizing the time of each unit perfectly and the rest periods after each intention . (Faraj,2002) reported that the learning tool contribute in the kinetical skills rapidly through the watching of kineti model that help in the tradition of motor learning. Worthwhile, the learning on any action learners should be in psychological and mental to gain specific experience fit the abilities and aptitudes in the educational environment (Salem,2001).
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Chrysanthemums Direct

Chrysanthemums Direct

Welcome to our latest mail order catalogue. This year, we are offering an excellent range, from the spectacular and exclusive Misty series to the outdoor spray and bloom varieties. Also available, for glasshouse culture, is the American Beauty series and a wide selection of All-Year-Round (Late) spray cultivars. New for 2010 is an extensive range of exhibition varieties. Also new this year is our Postal Flowers Service (see page 24 for full details). Plants and flowers can be ordered from this catalogue (plant order form on page 29), by telephone or via our secure website. Chrysanthemums Direct will be attending even more flower shows around the country this year. Our young plants and cut flower will be available to purchase at these events. All the flowers and plants that we sell are propagated from virus-free stock plants and grown, to the highest standard, on our nurseries in Cheshire. R. F. Lawrence and Sons, our parent company, has over 50 years horticultural experience. The family partnership includes Reg and Joyce Lawrence and their sons Trevor and Nigel. They are the only large-scale producer of Chrysanthemum blooms in the UK. Trevor Lawrence, along with Don Wright and Martyn Flint, set up Chrysanthemums Direct early last year to sell young plants direct to you.
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DeviceLinx XPort Direct/XChip Direct SoC User Guide

DeviceLinx XPort Direct/XChip Direct SoC User Guide

The XPort Direct has two general purpose I/O pins, CP1 and CP2, which support the following functions: general purpose input, general purpose output, and modem control input signal. These GPIO pins can control devices such as relays, servers, lights, monitor switches, sensors, and even processes such as data transfer. The modem control input (modem_control_in) functionality is supported in our standard firmware; where this functionality is incorporated into some of the channel connect/disconnect settings. With custom applications, the general purpose input/output functionality can be used for event signaling and/or triggering.
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