[{"status":"public","type":"journal_article","article_type":"original","_id":"7418","department":[{"_id":"ChWo"}],"date_updated":"2023-09-06T15:22:23Z","intvolume":" 38","month":"11","scopus_import":"1","oa_version":"None","abstract":[{"lang":"eng","text":"Multiple importance sampling (MIS) has become an indispensable tool in Monte Carlo rendering, widely accepted as a near-optimal solution for combining different sampling techniques. But an MIS combination, using the common balance or power heuristics, often results in an overly defensive estimator, leading to high variance. We show that by generalizing the MIS framework, variance can be substantially reduced. Specifically, we optimize one of the combined sampling techniques so as to decrease the overall variance of the resulting MIS estimator. We apply the approach to the computation of direct illumination due to an HDR environment map and to the computation of global illumination using a path guiding algorithm. The implementation can be as simple as subtracting a constant value from the tabulated sampling density done entirely in a preprocessing step. This produces a consistent noise reduction in all our tests with no negative influence on run time, no artifacts or bias, and no failure cases."}],"issue":"6","volume":38,"language":[{"iso":"eng"}],"publication_status":"published","publication_identifier":{"eissn":["1557-7368"],"issn":["0730-0301"]},"article_number":"151","title":"MIS compensation: Optimizing sampling techniques in multiple importance sampling","external_id":{"isi":["000498397300001"]},"article_processing_charge":"No","author":[{"last_name":"Karlík","full_name":"Karlík, Ondřej","first_name":"Ondřej"},{"first_name":"Martin","last_name":"Šik","full_name":"Šik, Martin"},{"first_name":"Petr","full_name":"Vévoda, Petr","last_name":"Vévoda"},{"full_name":"Skrivan, Tomas","last_name":"Skrivan","id":"486A5A46-F248-11E8-B48F-1D18A9856A87","first_name":"Tomas"},{"first_name":"Jaroslav","last_name":"Křivánek","full_name":"Křivánek, Jaroslav"}],"user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","citation":{"ista":"Karlík O, Šik M, Vévoda P, Skrivan T, Křivánek J. 2019. MIS compensation: Optimizing sampling techniques in multiple importance sampling. ACM Transactions on Graphics. 38(6), 151.","chicago":"Karlík, Ondřej, Martin Šik, Petr Vévoda, Tomas Skrivan, and Jaroslav Křivánek. “MIS Compensation: Optimizing Sampling Techniques in Multiple Importance Sampling.” ACM Transactions on Graphics. ACM, 2019. https://doi.org/10.1145/3355089.3356565.","apa":"Karlík, O., Šik, M., Vévoda, P., Skrivan, T., & Křivánek, J. (2019). MIS compensation: Optimizing sampling techniques in multiple importance sampling. ACM Transactions on Graphics. ACM. https://doi.org/10.1145/3355089.3356565","ama":"Karlík O, Šik M, Vévoda P, Skrivan T, Křivánek J. MIS compensation: Optimizing sampling techniques in multiple importance sampling. ACM Transactions on Graphics. 2019;38(6). doi:10.1145/3355089.3356565","short":"O. Karlík, M. Šik, P. Vévoda, T. Skrivan, J. Křivánek, ACM Transactions on Graphics 38 (2019).","ieee":"O. Karlík, M. Šik, P. Vévoda, T. Skrivan, and J. Křivánek, “MIS compensation: Optimizing sampling techniques in multiple importance sampling,” ACM Transactions on Graphics, vol. 38, no. 6. ACM, 2019.","mla":"Karlík, Ondřej, et al. “MIS Compensation: Optimizing Sampling Techniques in Multiple Importance Sampling.” ACM Transactions on Graphics, vol. 38, no. 6, 151, ACM, 2019, doi:10.1145/3355089.3356565."},"publisher":"ACM","quality_controlled":"1","date_created":"2020-01-30T10:19:43Z","date_published":"2019-11-01T00:00:00Z","doi":"10.1145/3355089.3356565","publication":"ACM Transactions on Graphics","day":"01","year":"2019","isi":1},{"abstract":[{"text":"We present a thermodynamically based approach to the design of models for viscoelastic fluids with stress diffusion effect. In particular, we show how to add a stress diffusion term to some standard viscoelastic rate-type models (Giesekus, FENE-P, Johnson–Segalman, Phan-Thien–Tanner and Bautista–Manero–Puig) so that the resulting models with the added stress diffusion term are thermodynamically consistent in the sense that they obey the first and the second law of thermodynamics. We point out the potential applications of the provided thermodynamical background in the study of flows of fluids described by the proposed models.","lang":"eng"}],"oa_version":"Preprint","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1902.07983"}],"scopus_import":"1","intvolume":" 2107","month":"05","publication_status":"published","language":[{"iso":"eng"}],"volume":2107,"_id":"6642","conference":{"name":"8th International Conference on Novel Trends in Rheology","end_date":"2019-07-31","location":"Zlin, Czech Republic","start_date":"2019-07-30"},"type":"conference","status":"public","date_updated":"2024-02-28T13:01:28Z","department":[{"_id":"ChWo"}],"oa":1,"quality_controlled":"1","publisher":"AIP Publishing","year":"2019","isi":1,"publication":"AIP Conference Proceedings","day":"21","date_created":"2019-07-15T10:07:09Z","doi":"10.1063/1.5109493","date_published":"2019-05-21T00:00:00Z","article_number":"020002","citation":{"mla":"Dostalík, Mark, et al. “On Diffusive Variants of Some Classical Viscoelastic Rate-Type Models.” AIP Conference Proceedings, vol. 2107, 020002, AIP Publishing, 2019, doi:10.1063/1.5109493.","short":"M. Dostalík, V. Pruša, T. Skrivan, in:, AIP Conference Proceedings, AIP Publishing, 2019.","ieee":"M. Dostalík, V. Pruša, and T. Skrivan, “On diffusive variants of some classical viscoelastic rate-type models,” in AIP Conference Proceedings, Zlin, Czech Republic, 2019, vol. 2107.","ama":"Dostalík M, Pruša V, Skrivan T. On diffusive variants of some classical viscoelastic rate-type models. In: AIP Conference Proceedings. Vol 2107. AIP Publishing; 2019. doi:10.1063/1.5109493","apa":"Dostalík, M., Pruša, V., & Skrivan, T. (2019). On diffusive variants of some classical viscoelastic rate-type models. In AIP Conference Proceedings (Vol. 2107). Zlin, Czech Republic: AIP Publishing. https://doi.org/10.1063/1.5109493","chicago":"Dostalík, Mark, Vít Pruša, and Tomas Skrivan. “On Diffusive Variants of Some Classical Viscoelastic Rate-Type Models.” In AIP Conference Proceedings, Vol. 2107. AIP Publishing, 2019. https://doi.org/10.1063/1.5109493.","ista":"Dostalík M, Pruša V, Skrivan T. 2019. On diffusive variants of some classical viscoelastic rate-type models. AIP Conference Proceedings. 8th International Conference on Novel Trends in Rheology vol. 2107, 020002."},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","article_processing_charge":"No","external_id":{"isi":["000479303100002"],"arxiv":["1902.07983"]},"author":[{"first_name":"Mark","full_name":"Dostalík, Mark","last_name":"Dostalík"},{"first_name":"Vít","full_name":"Pruša, Vít","last_name":"Pruša"},{"first_name":"Tomas","id":"486A5A46-F248-11E8-B48F-1D18A9856A87","last_name":"Skrivan","full_name":"Skrivan, Tomas"}],"title":"On diffusive variants of some classical viscoelastic rate-type models"},{"language":[{"iso":"eng"}],"file":[{"content_type":"application/pdf","access_level":"open_access","relation":"main_file","file_id":"8627","checksum":"8edb90da8a72395eb5d970580e0925b6","success":1,"date_updated":"2020-10-08T08:38:23Z","file_size":54309947,"creator":"wojtan","date_created":"2020-10-08T08:38:23Z","file_name":"exnbflip.pdf"}],"publication_status":"published","publication_identifier":{"issn":["0167-7055"]},"ec_funded":1,"issue":"2","volume":37,"oa_version":"Submitted Version","abstract":[{"lang":"eng","text":"The Fluid Implicit Particle method (FLIP) reduces numerical dissipation by combining particles with grids. To improve performance, the subsequent narrow band FLIP method (NB‐FLIP) uses a FLIP‐based fluid simulation only near the liquid surface and a traditional grid‐based fluid simulation away from the surface. This spatially‐limited FLIP simulation significantly reduces the number of particles and alleviates a computational bottleneck. In this paper, we extend the NB‐FLIP idea even further, by allowing a simulation to transition between a FLIP‐like fluid simulation and a grid‐based simulation in arbitrary locations, not just near the surface. This approach leads to even more savings in memory and computation, because we can concentrate the particles only in areas where they are needed. More importantly, this new method allows us to seamlessly transition to smooth implicit surface geometry wherever the particle‐based simulation is unnecessary. Consequently, our method leads to a practical algorithm for avoiding the noisy surface artifacts associated with particle‐based liquid simulations, while simultaneously maintaining the benefits of a FLIP simulation in regions of dynamic motion."}],"intvolume":" 37","month":"05","scopus_import":"1","alternative_title":["Eurographics"],"ddc":["006"],"date_updated":"2023-09-11T14:00:26Z","department":[{"_id":"ChWo"}],"file_date_updated":"2020-10-08T08:38:23Z","_id":"135","status":"public","article_type":"original","type":"journal_article","publication":"Computer Graphics Forum","day":"22","year":"2018","isi":1,"has_accepted_license":"1","date_created":"2018-12-11T11:44:49Z","doi":"10.1111/cgf.13351","date_published":"2018-05-22T00:00:00Z","page":"169 - 177","oa":1,"quality_controlled":"1","publisher":"Wiley","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","citation":{"apa":"Sato, T., Wojtan, C., Thuerey, N., Igarashi, T., & Ando, R. (2018). Extended narrow band FLIP for liquid simulations. Computer Graphics Forum. Wiley. https://doi.org/10.1111/cgf.13351","ama":"Sato T, Wojtan C, Thuerey N, Igarashi T, Ando R. Extended narrow band FLIP for liquid simulations. Computer Graphics Forum. 2018;37(2):169-177. doi:10.1111/cgf.13351","short":"T. Sato, C. Wojtan, N. Thuerey, T. Igarashi, R. Ando, Computer Graphics Forum 37 (2018) 169–177.","ieee":"T. Sato, C. Wojtan, N. Thuerey, T. Igarashi, and R. Ando, “Extended narrow band FLIP for liquid simulations,” Computer Graphics Forum, vol. 37, no. 2. Wiley, pp. 169–177, 2018.","mla":"Sato, Takahiro, et al. “Extended Narrow Band FLIP for Liquid Simulations.” Computer Graphics Forum, vol. 37, no. 2, Wiley, 2018, pp. 169–77, doi:10.1111/cgf.13351.","ista":"Sato T, Wojtan C, Thuerey N, Igarashi T, Ando R. 2018. Extended narrow band FLIP for liquid simulations. Computer Graphics Forum. 37(2), 169–177.","chicago":"Sato, Takahiro, Chris Wojtan, Nils Thuerey, Takeo Igarashi, and Ryoichi Ando. “Extended Narrow Band FLIP for Liquid Simulations.” Computer Graphics Forum. Wiley, 2018. https://doi.org/10.1111/cgf.13351."},"title":"Extended narrow band FLIP for liquid simulations","article_processing_charge":"No","external_id":{"isi":["000434085600016"]},"author":[{"first_name":"Takahiro","full_name":"Sato, Takahiro","last_name":"Sato"},{"full_name":"Wojtan, Christopher J","orcid":"0000-0001-6646-5546","last_name":"Wojtan","first_name":"Christopher J","id":"3C61F1D2-F248-11E8-B48F-1D18A9856A87"},{"last_name":"Thuerey","full_name":"Thuerey, Nils","first_name":"Nils"},{"first_name":"Takeo","full_name":"Igarashi, Takeo","last_name":"Igarashi"},{"first_name":"Ryoichi","full_name":"Ando, Ryoichi","last_name":"Ando"}],"project":[{"_id":"2533E772-B435-11E9-9278-68D0E5697425","call_identifier":"H2020","grant_number":"638176","name":"Efficient Simulation of Natural Phenomena at Extremely Large Scales"}]},{"issue":"4","related_material":{"link":[{"url":"https://ist.ac.at/en/news/new-water-simulation-captures-small-details-even-in-large-scenes/","relation":"press_release","description":"News on IST Homepage"}]},"volume":37,"ec_funded":1,"file":[{"checksum":"db75ebabe2ec432bf41389e614d6ef62","file_id":"5744","content_type":"application/pdf","access_level":"open_access","relation":"main_file","date_created":"2018-12-18T09:59:23Z","file_name":"2018_ACM_Jeschke.pdf","date_updated":"2020-07-14T12:44:45Z","file_size":22185016,"creator":"dernst"}],"language":[{"iso":"eng"}],"publication_status":"published","month":"07","intvolume":" 37","scopus_import":"1","alternative_title":["SIGGRAPH"],"oa_version":"Published Version","acknowledged_ssus":[{"_id":"ScienComp"}],"abstract":[{"text":"The current state of the art in real-time two-dimensional water wave simulation requires developers to choose between efficient Fourier-based methods, which lack interactions with moving obstacles, and finite-difference or finite element methods, which handle environmental interactions but are significantly more expensive. This paper attempts to bridge this long-standing gap between complexity and performance, by proposing a new wave simulation method that can faithfully simulate wave interactions with moving obstacles in real time while simultaneously preserving minute details and accommodating very large simulation domains.\r\n\r\nPrevious methods for simulating 2D water waves directly compute the change in height of the water surface, a strategy which imposes limitations based on the CFL condition (fast moving waves require small time steps) and Nyquist's limit (small wave details require closely-spaced simulation variables). This paper proposes a novel wavelet transformation that discretizes the liquid motion in terms of amplitude-like functions that vary over space, frequency, and direction, effectively generalizing Fourier-based methods to handle local interactions. Because these new variables change much more slowly over space than the original water height function, our change of variables drastically reduces the limitations of the CFL condition and Nyquist limit, allowing us to simulate highly detailed water waves at very large visual resolutions. Our discretization is amenable to fast summation and easy to parallelize. We also present basic extensions like pre-computed wave paths and two-way solid fluid coupling. Finally, we argue that our discretization provides a convenient set of variables for artistic manipulation, which we illustrate with a novel wave-painting interface.","lang":"eng"}],"file_date_updated":"2020-07-14T12:44:45Z","department":[{"_id":"ChWo"}],"ddc":["000"],"date_updated":"2024-02-28T13:58:51Z","status":"public","type":"journal_article","tmp":{"name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","image":"/images/cc_by_nc_sa.png","legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode","short":"CC BY-NC-SA (4.0)"},"_id":"134","date_published":"2018-07-30T00:00:00Z","doi":"10.1145/3197517.3201336","date_created":"2018-12-11T11:44:48Z","day":"30","publication":"ACM Transactions on Graphics","has_accepted_license":"1","isi":1,"year":"2018","publisher":"ACM","quality_controlled":"1","oa":1,"title":"Water surface wavelets","author":[{"first_name":"Stefan","id":"44D6411A-F248-11E8-B48F-1D18A9856A87","last_name":"Jeschke","full_name":"Jeschke, Stefan"},{"first_name":"Tomas","id":"486A5A46-F248-11E8-B48F-1D18A9856A87","full_name":"Skrivan, Tomas","last_name":"Skrivan"},{"full_name":"Mueller Fischer, Matthias","last_name":"Mueller Fischer","first_name":"Matthias"},{"first_name":"Nuttapong","full_name":"Chentanez, Nuttapong","last_name":"Chentanez"},{"first_name":"Miles","full_name":"Macklin, Miles","last_name":"Macklin"},{"first_name":"Christopher J","id":"3C61F1D2-F248-11E8-B48F-1D18A9856A87","last_name":"Wojtan","full_name":"Wojtan, Christopher J","orcid":"0000-0001-6646-5546"}],"publist_id":"7789","article_processing_charge":"No","external_id":{"isi":["000448185000055"]},"user_id":"2EBD1598-F248-11E8-B48F-1D18A9856A87","citation":{"short":"S. Jeschke, T. Skrivan, M. Mueller Fischer, N. Chentanez, M. Macklin, C. Wojtan, ACM Transactions on Graphics 37 (2018).","ieee":"S. Jeschke, T. Skrivan, M. Mueller Fischer, N. Chentanez, M. Macklin, and C. Wojtan, “Water surface wavelets,” ACM Transactions on Graphics, vol. 37, no. 4. ACM, 2018.","apa":"Jeschke, S., Skrivan, T., Mueller Fischer, M., Chentanez, N., Macklin, M., & Wojtan, C. (2018). Water surface wavelets. ACM Transactions on Graphics. ACM. https://doi.org/10.1145/3197517.3201336","ama":"Jeschke S, Skrivan T, Mueller Fischer M, Chentanez N, Macklin M, Wojtan C. Water surface wavelets. ACM Transactions on Graphics. 2018;37(4). doi:10.1145/3197517.3201336","mla":"Jeschke, Stefan, et al. “Water Surface Wavelets.” ACM Transactions on Graphics, vol. 37, no. 4, 94, ACM, 2018, doi:10.1145/3197517.3201336.","ista":"Jeschke S, Skrivan T, Mueller Fischer M, Chentanez N, Macklin M, Wojtan C. 2018. Water surface wavelets. ACM Transactions on Graphics. 37(4), 94.","chicago":"Jeschke, Stefan, Tomas Skrivan, Matthias Mueller Fischer, Nuttapong Chentanez, Miles Macklin, and Chris Wojtan. “Water Surface Wavelets.” ACM Transactions on Graphics. ACM, 2018. https://doi.org/10.1145/3197517.3201336."},"project":[{"name":"Efficient Simulation of Natural Phenomena at Extremely Large Scales","grant_number":"638176","call_identifier":"H2020","_id":"2533E772-B435-11E9-9278-68D0E5697425"},{"grant_number":"665385","name":"International IST Doctoral Program","_id":"2564DBCA-B435-11E9-9278-68D0E5697425","call_identifier":"H2020"}],"article_number":"94"},{"department":[{"_id":"ChWo"}],"file_date_updated":"2020-07-14T12:46:34Z","ddc":["006"],"date_updated":"2023-02-23T12:20:26Z","status":"public","type":"journal_article","article_type":"original","_id":"470","volume":36,"issue":"4","ec_funded":1,"file":[{"file_name":"wavepackets_final.pdf","date_created":"2020-01-24T09:32:35Z","file_size":13131683,"date_updated":"2020-07-14T12:46:34Z","creator":"wojtan","checksum":"82a3b2bfeee4ddef16ecc21675d1a48a","file_id":"7359","content_type":"application/pdf","relation":"main_file","access_level":"open_access"}],"language":[{"iso":"eng"}],"publication_identifier":{"issn":["07300301"]},"publication_status":"published","month":"07","intvolume":" 36","scopus_import":1,"oa_version":"Published Version","abstract":[{"lang":"eng","text":"This paper presents a method for simulating water surface waves as a displacement field on a 2D domain. Our method relies on Lagrangian particles that carry packets of water wave energy; each packet carries information about an entire group of wave trains, as opposed to only a single wave crest. Our approach is unconditionally stable and can simulate high resolution geometric details. This approach also presents a straightforward interface for artistic control, because it is essentially a particle system with intuitive parameters like wavelength and amplitude. Our implementation parallelizes well and runs in real time for moderately challenging scenarios."}],"acknowledged_ssus":[{"_id":"ScienComp"}],"title":"Water wave packets","publist_id":"7350","author":[{"full_name":"Jeschke, Stefan","last_name":"Jeschke","first_name":"Stefan","id":"44D6411A-F248-11E8-B48F-1D18A9856A87"},{"orcid":"0000-0001-6646-5546","full_name":"Wojtan, Christopher J","last_name":"Wojtan","first_name":"Christopher J","id":"3C61F1D2-F248-11E8-B48F-1D18A9856A87"}],"article_processing_charge":"Yes (in subscription journal)","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","citation":{"apa":"Jeschke, S., & Wojtan, C. (2017). Water wave packets. ACM Transactions on Graphics. ACM. https://doi.org/10.1145/3072959.3073678","ama":"Jeschke S, Wojtan C. Water wave packets. ACM Transactions on Graphics. 2017;36(4). doi:10.1145/3072959.3073678","short":"S. Jeschke, C. Wojtan, ACM Transactions on Graphics 36 (2017).","ieee":"S. Jeschke and C. Wojtan, “Water wave packets,” ACM Transactions on Graphics, vol. 36, no. 4. ACM, 2017.","mla":"Jeschke, Stefan, and Chris Wojtan. “Water Wave Packets.” ACM Transactions on Graphics, vol. 36, no. 4, 103, ACM, 2017, doi:10.1145/3072959.3073678.","ista":"Jeschke S, Wojtan C. 2017. Water wave packets. ACM Transactions on Graphics. 36(4), 103.","chicago":"Jeschke, Stefan, and Chris Wojtan. “Water Wave Packets.” ACM Transactions on Graphics. ACM, 2017. https://doi.org/10.1145/3072959.3073678."},"project":[{"grant_number":"638176","name":"Efficient Simulation of Natural Phenomena at Extremely Large Scales","_id":"2533E772-B435-11E9-9278-68D0E5697425","call_identifier":"H2020"}],"article_number":"103","doi":"10.1145/3072959.3073678","date_published":"2017-07-01T00:00:00Z","date_created":"2018-12-11T11:46:39Z","day":"01","publication":"ACM Transactions on Graphics","has_accepted_license":"1","year":"2017","publisher":"ACM","quality_controlled":"1","oa":1}]