# NVIDIA Is Simulating 100,000 Hair Strands!

## Метаданные

- **Канал:** Two Minute Papers
- **YouTube:** https://www.youtube.com/watch?v=eVjhOzY9KvY
- **Дата:** 17.05.2023
- **Длительность:** 6:21
- **Просмотры:** 277,380

## Описание

❤️ Check out Lambda here and sign up for their GPU Cloud: https://lambdalabs.com/papers

📝 The #NVIDIA paper  "Interactive Hair Simulation on the GPU using ADMM" is available here:
https://research.nvidia.com/publication/2023-08_interactive-hair-simulation-gpu-using-admm

My latest paper on simulations that look almost like reality is available for free here:
https://rdcu.be/cWPfD 

Or this is the orig. Nature Physics link with clickable citations:
https://www.nature.com/articles/s41567-022-01788-5

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## Содержание

### [0:00](https://www.youtube.com/watch?v=eVjhOzY9KvY) Segment 1 (00:00 - 05:00)

Dear Fellow Scholars, this is Two Minute Papers with Dr. Károly Zsolnai-Fehér. Dr. Papers. Today we are going to have a look at what is new in the physics of hair in virtual worlds. You see, this is a challenging problem where these virtual characters are given fur or other kinds of hair, and we have to simulate their interactions via Coulomb-friction. This is dry friction when two surfaces come into contact. Which typically arises when we have lots of hair, and thus, lots of strand-strand interactions. That happens a great deal whenever a wolf is jumping or running around. And when things start moving, these simulations can get very, very messy. This previous paper that we talked about earlier can resolve such conflicts, and create beautiful, realistic hair simulations. However, this class of algorithms typically takes forever to compute. They are typically not even close to real time. However, NVIDIA has also done some research on it, these algorithms typically run on your graphics card, and are fast enough to be deployed in real video games and other virtual worlds. But wait, these can not resolve scenes that are as detailed as the ones in the previous paper. With this, we have to resort to much simpler models and fewer hair strands, many of which typically move together. To the best of my knowledge, they also haven’t seen a lot of improvements over the last few years. So, are we done? Is there no hope for quick and detailed hair simulations? Well, sometimes, all it takes is just one person. One scientist. Yes, you are seeing correctly, this is a one-author SIGGRAPH paper from NVIDIA on this exact topic, so I am itching to look at it together. And…whoa. Now that is a next-generation hair simulation right there! It looks like almost every single hair strand is simulated independently. My goodness! And as I am a light transport researcher by trade, I have to note that I love how the specular highlights are computed here. And what you see here is the favorite pastime of the computer graphics researcher. And here. Yes, this time I hope it will not get as painful as with some of the previous papers. But it looks like this character is getting away by just getting its hair cut. Very fun experiment indeed. And now comes the bombshell: These models have thousands of hair strands that are made up of 120,000 points, that is incredible, so now I feel that it’s appropriate to pop the question. So, it does all this how quickly exactly? Well, hold on to your papers Fellow Scholars, because it does all this in 17 milliseconds. Yes, all this is happening in real time. And these are not some run of the mill simulations that we saw earlier. No sir! These are super detailed. And if we pop the hood and look at the internal workings of the algorithm, we see that most of the time is spent with detecting and resolving these collisions, and oh my goodness. Are you seeing what I am seeing? Oh yes, depending on the current state of the hair, there is substantial variation between the execution times of the algorithm. That is big trouble! Why? Well, because if we are in any kind of virtual world or we are playing a video game, we have to make sure that every individual picture is computed quickly and on time. If one moment we have 10 frames per second, and the next moment we have 60, what we get is a jarring experience. Is this not going to make it? Do not despair for a second, because most of the time it runs so quickly, it only takes a couple milliseconds, and sometimes not even a millisecond. So I think this one is going to do just fine and hopefully will be implemented in the video games of the future. What a time to be alive! But just one more quick question - is this actually accurate? Well, let’s have a closer look at these two lines, and there we have our answer. Now, I hear you saying, Dr. Papers, why are you saying that there are two lines here, I see only one! And that is exactly the point. The simulated results are so close to reality that the measurements essentially overlap. And all that in real time. That is incredible.

### [5:00](https://www.youtube.com/watch?v=eVjhOzY9KvY&t=300s) Segment 2 (05:00 - 06:00)

And now you can see that the papers that we discuss here are real, they get out of there in the real world to be used in real products by millions of people. And sometimes, all this comes from the ingenuity of one Fellow Scholar. One scientist is all it takes to change everything. Huge congratulations! Thanks for watching and for your generous support, and I'll see you next time!

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*Источник: https://ekstraktznaniy.ru/video/13169*