# An Efficient Scattering Material Representation | Two Minute Papers #151 ## Метаданные - **Канал:** Two Minute Papers - **YouTube:** https://www.youtube.com/watch?v=oleylS5XGpg - **Дата:** 06.05.2017 - **Длительность:** 3:35 - **Просмотры:** 11,197 - **Источник:** https://ekstraktznaniy.ru/video/14665 ## Описание The paper "Downsampling Scattering Parameters for Rendering Anisotropic Media" and its source code is available here: https://shuangz.com/projects/multires-sa16/ Two Minute Papers Merch: US: http://twominutepapers.com/ EU/Worldwide: https://shop.spreadshirt.net/TwoMinutePapers/ WE WOULD LIKE TO THANK OUR GENEROUS PATREON SUPPORTERS WHO MAKE TWO MINUTE PAPERS POSSIBLE: Andrew Melnychuk, Christian Lawson, Daniel John Benton, Dave Rushton-Smith, Dennis Abts, e, Esa Turkulainen, Michael Albrecht, Sunil Kim, VR Wizard. https://www.patreon.com/TwoMinutePapers Music: Antarctica by Audionautix is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/) Artist: http://audionautix.com/ Thumbnail background image credit: https://pixabay.com/photo-1747666/ Splash screen/thumbnail design: Felícia Fehér - http://felicia.hu Károly Zsolnai-Fehér's links: Facebook → https://www.facebook.com/TwoMinutePapers/ Twitter → https://twitter.com/karoly_zsolnai W ## Транскрипт ### [] Dear fellow scholars, this is two minute papers with Koa Eher. Have a look at these beautiful images representing these materials that you see here takes more than 25 GB of storage. You could store several featurelength movies on your hard drive using the same amount of storage. And this technique is able to compress all this 25 GB into 45 mgabytes ### Reference (2.1 GB) [0:22] without introducing any significant perceptible difference. That is close to a whopping 500 times more efficient representation. H this improved ### Ours (1 voxel cluster, 1 lobe) [0:35] representation not only helps easing the storage requirements of these assets, but it also makes the rendering times or in other words the process of creating these images via light simulation programs typically more than twice as fast to process. That is a ton of money and time saved for the artists. An important keyword in this piece of work is anisotropic scattering. So what does this mean exactly? The scattering part ### Reference (2.7 GB) [1:00] means that we have to imagine these materials not as a surface but as a volume in which rays of light bounce around and get absorbed. If we render a piece of cloth made of velvet, twill or a similar material, there are lots of microscopic differences in the surface. So much so that it is insufficient to treat them as a solid surface such as wood or metals. We have to think about ### Ours (2 voxel clusters, 2 lobes) [1:25] them as volumes. This is the scattering part. The anisotropy means that light can scatter unevenly in this medium. These rays don't bounce around in all directions with equal probability. This means that there is significant forward and backward scattering in these media making it even more difficult to create more optimized algorithms that simplify these scattering equations. If you look below here, you'll see these colorful images that researchers like to call difference images. It basically means that we create one image with the perfectly accurate technique as a reference. As expected, this reference image probably takes forever to compute, but is important to have as a yard stick. Then we compute one image with the proposed technique that is usually significantly faster. So we have these two images and sometimes the differences are so difficult to see, we have no way of knowing where the inaccuracies are. So what we do is subtract the two images from each other and assign a color coding for the differences. As the error may be spatially varying, this is super useful because we can recognize exactly where the information is lost. The angrier the colors are, the higher the error is in a given region. As you can see, the proposed technique is significantly more accurate in representing this medium than a naive method using the same amount of storage. This paper is extraordinarily well written. It is one of the finest pieces of craftsmanship I've come along in a long while. And yes, it is a crime not having a look at it. Also, if you like this episode, make sure to subscribe to the series and check out our other videos. We have more than 150 episodes for you ready to go right now. You'll love it and there will be lots of fun to be had. Thanks for watching and for your generous support. And I see you next time. Heat.