The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform
Koji Koyamada - One of the best experts on this subject based on the ideXlab platform.
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error visualization of tetrahedral subdivision approach for Trilinear Interpolation
International Conference on Parallel and Distributed Systems, 2000Co-Authors: Akio Doi, Koji KoyamadaAbstract:A linear Interpolation scheme inside a tetrahedral cell often causes a large Interpolation error when field values change drastically. However, the error has not been analysed and visualized thoroughly In order to understand the error distribution inside a tetrahedral cell, we propose two types of error norms, which are both an Interpolation function error norm and a field data error norm. These error norms make it possible to compare the linear Interpolation function with a Trilinear Interpolation function that has often been used in rectilinear grid cell, and visualize the error distribution by using iso-surface display.
Balazs Csebfalvi - One of the best experts on this subject based on the ideXlab platform.
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beyond Trilinear Interpolation higher quality for free
ACM Transactions on Graphics, 2019Co-Authors: Balazs CsebfalviAbstract:In volume-rendering applications, it is a de facto standard to reconstruct the underlying continuous function by using Trilinear Interpolation, and to estimate the gradients for the shading computations by calculating central differences on the fly. In a GPU implementation, this requires seven Trilinear texture samples: one for the function reconstruction, and six for the gradient estimation. In this paper, for the first time, we show that the six additional samples can be used not just for gradient estimation, but for significantly improving the quality of the function reconstruction as well. As the additional arithmetic operations can be performed in the shadow of the texture fetches, we can achieve this quality improvement for free without reducing the rendering performance at all. Therefore, our method can completely replace the standard Trilinear Interpolation in the practice of GPU-accelerated volume rendering.
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dc splines revisiting the Trilinear Interpolation on the body centered cubic lattice
Vision Modeling and Visualization, 2010Co-Authors: Balazs Domonkos, Balazs CsebfalviAbstract:In this paper, we thoroughly study a Trilinear Interpolation scheme previously proposed for the Body-Centered Cubic (BCC) lattice. We think that, up to now, this technique has not received the attention that it deserves. By a frequency-domain analysis we show that it can isotropically suppress those aliasing spectra that contribute most to the postaliasing effect. Furthermore, we present an efficient GPU implementation, which requires only six Trilinear texture fetches per sample. Overall, we demonstrate that the Trilinear Interpolation on the BCC lattice is competitive to the linear box-spline Interpolation in terms of both efficiency and image quality. As a generalization to higher-order reconstruction, we introduce DC-splines that are constructed by convolving a Discrete filter with a Continuous filter, and easy to adapt to the Face-Centered Cubic (FCC) lattice as well.
P Manser - One of the best experts on this subject based on the ideXlab platform.
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su f brd 03 determination of plan robustness for systematic setup errors using Trilinear Interpolation
Medical Physics, 2014Co-Authors: M K Fix, W Volken, D Frei, D Terribilini, Dal A Pra, M Schmuecking, P ManserAbstract:Purpose: Treatment plan evaluations in radiotherapy are currently ignoring the dosimetric impact of setup uncertainties. The determination of the robustness for systematic errors is rather computational intensive. This work investigates Interpolation schemes to quantify the robustness of treatment plans for systematic errors in terms of efficiency and accuracy. Methods: The impact of systematic errors on dose distributions for patient treatment plans is determined by using the Swiss Monte Carlo Plan (SMCP). Errors in all translational directions are considered, ranging from −3 to +3 mm in mm steps. For each systematic error a full MC dose calculation is performed leading to 343 dose calculations, used as benchmarks. The Interpolation uses only a subset of the 343 calculations, namely 9, 15 or 27, and determines all dose distributions by Trilinear Interpolation. This procedure is applied for a prostate and a head and neck case using Volumetric Modulated Arc Therapy with 2 arcs. The relative differences of the dose volume histograms (DVHs) of the target and the organs at risks are compared. Finally, the Interpolation schemes are used to compare robustness of 4- versus 2-arcs in the head and neck treatment plan. Results: Relative local differences of the DVHs increase for decreasing number of dose calculations used in the Interpolation. The mean deviations are <1%, 3.5% and 6.5% for a subset of 27, 15 and 9 used dose calculations, respectively. Thereby the dose computation times are reduced by factors of 13, 25 and 43, respectively. The comparison of the 4- versus 2-arcs plan shows a decrease in robustness; however, this is outweighed by the dosimetric improvements. Conclusion: The results of this study suggest that the use of Trilinear Interpolation to determine the robustness of treatment plans can remarkably reduce the number of dose calculations. This work was supported by Varian Medical Systems. This work was supported by Varian Medical Systems
Xavier Gonze - One of the best experts on this subject based on the ideXlab platform.
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novel Trilinear Interpolation technique to improve the convergence rate of bethe salpeter calculations
CECAM Workshop "Electron-vibration coupling : theoretical and numerical challenges", 2015Co-Authors: Yannick Gillet, Matteo Giantomassi, Xavier GonzeAbstract:The inclusion of excitonic effects in semiconductors with the Bethe-Salpeter equation leads to good agreement of the optical spectra with experimental measurements. However, this approach requires in general very fine meshes of wavevectors in the Brillouin Zone in order to obtain well-converged spectra, preventing access to numerous derived quantities, as depicted e.g. in [1]. Rohlfing [2] and Kammerlander [3] have proposed different techniques to treat such fine meshes, allowing to decrease the work load to reach a given accuracy. We have designed a new methodology, based on a Trilinear Interpolation technique within the Brillouin zone, combined with the Lanczos algorithm, also incorporating ideas from Ref. [2,3], like a double-grid technique, to achieve superiour speed-up and memory use. We describe the implementation, and show results for selected materials. References [1] Y. Gillet, M. Giantomassi and X. Gonze, Phys. Rev. B 88, 094305 (2013) [2] M. Rohlfing and S.G. Louie, Phys. Rev. B 62, 4927 (2000) [3] D. Kammerlander, S. Botti, M.A.L. Marques, A. Marini and C. Attaccalite, Phys. Rev. B 86, 125203 (2012)
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efficient Trilinear Interpolation technique for bethe salpeter calculations of optical spectra
7th Abinit Developer Workshop 2015, 2015Co-Authors: Yannick Gillet, Matteo Giantomassi, Xavier GonzeAbstract:The inclusion of excitonic effects in semiconductors with the Bethe-Salpeter equation leads to good agreement of the optical spectra with experimental measurements. However, this approach requires in general very fine meshes of wavevectors in the Brillouin Zone in order to obtain well-converged spectra, with very heavy computational load, preventing access to numerous derived quantities, as e.g. Raman intensities [1]. We present a new methodology that allows to decrease the work load to reach a given accuracy. This technique is based on a Trilinear Interpolation technique within the Brillouin zone, combined with the Lanczos algorithm and double-grid technique, in the spirit of Refs. [2] and [3], to achieve efficient speed-up and memory use. The technique is benchmarked in terms of accuracy on selected test cases. The scaling has also been studied from low to very-high density of points in the Brillouin Zone, showing a much better scaling than a complete Bethe-Salpeter. This approach might be used in the future for more complex calculations of optical properties. References [1] Y. Gillet, M. Giantomassi, and X. Gonze, Phys. Rev. B 88, 094305 (2013). [2] M. Rohlfing and S. G. Louie, Phys. Rev. B 62, 4927 (2000). [3] D. Kammerlander, S. Botti, M. A. L. Marques, A. Marini and C. Attaccalite, Phys. Rev. B 86, 125203 (2012).
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novel Trilinear Interpolation technique to improve the convergence rate of bethe salpeter calculations
ETSF Young Researchers' Meeting 2014: evolution of ab-initio methods for condensed matter - connection with experiments and industry, 2014Co-Authors: Yannick Gillet, Matteo Giantomassi, Xavier GonzeAbstract:The inclusion of excitonic effects in semiconductors with the Bethe-Salpeter equation leads to good agreement of the optical spectra with experimental measurements. However, this approach requires in general very fine meshes of wavevectors in the Brillouin Zone in order to obtain well-converged spectra, preventing access to numerous derived quantities, as depicted e.g. in [1]. Rohlfing [2] and Kammerlander [3] have proposed different techniques to treat such fine meshes, allowing to decrease the work load to reach a given accuracy. We have designed a new methodology, based on a Trilinear Interpolation technique within the Brillouin zone, combined with the Lanczos algorithm, also incorporating ideas from Ref. [2,3], like a double-grid technique, to achieve superiour speed-up and memory use. We describe the implementation, and show results for selected materials. [1] Y. Gillet, M. Giantomassi and X. Gonze, Phys. Rev. B 88, 094305 (2013) [2] M. Rohlfing and S.G. Louie, Phys. Rev. B 62, 4927 (2000) [3] D. Kammerlander, S. Botti, M.A.L. Marques, A. Marini and C. Attaccalite, Phys. Rev. B 86, 125203 (2012)
Jan J Wilkens - One of the best experts on this subject based on the ideXlab platform.
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approximation of dose quality indicator values in multi criteria optimized mco volumetric modulated arc therapy vmat treatment planning using Trilinear dose Interpolation
Zeitschrift Fur Medizinische Physik, 2020Co-Authors: Christian Harrer, Wolfgang Ullrich, Stefan Schell, Jan J WilkensAbstract:Abstract Purpose To approximate dose-volume histogram (DVH) based quality indicators in volumetric modulated arc therapy (VMAT) planning using multi-criteria optimization (MCO) with a low number of composite optimization parameters. Methods The solution space for VMAT optimization with a low number of composite optimization parameters is approximated by Trilinear dose inter- polation and prediction of dose-volume-histogram (DVH) based plan quality indicator values. To assess the approximation quality a diverse dataset of 44 cranial and 18 spine patient geometries was chosen. Optimization results are governed by three composite parameters focusing on target-organ-at-risk- (OAR)-trade-off, overall healthy tissue sparing, and delivery/quality assurance complexity. 21,266 optimized dose distributions were pre-calculated and the numerical values for a choice of 10 DVH points, referred to as plan quality indicators, were stored to serve as ground truth. Using a subset of 8 and 27 pre-calculated optimization results, dose distributions for unknown parameter values were approximated by Trilinear Interpolation. The resulting quality indicator values were compared to the previously obtained exact solutions. Results The magnitude of the deviation between exact and approximated values varied largely with respect to patient geometry and the criterion under investigation. Approximation with 27 pre-calculated results yielded lower deviations than approximation with 8 results, at the cost of a higher pre-calculation workload. Conclusions Solution space approximation via Trilinear dose Interpolation in VMAT treatment planning governed by composite optimization parameters is possible without further knowledge of the internal implementation of the underlying optimizer. Maximum average deviations between approxi- mation and actual values of characteristic dose quality indicators below 1% (cranial) and 8% (spine) allow for a quick qualitative assessment of the possible solution landscape.
