Graphical, textual ramblings of a coder.
What about small TessFactors? This commonly happens in the form of a base patch with DiceFactor << MaxDiceFactor or during splitting where SplitFactor << MaxSplitFactor. For example if the max factor is 8 then a patch could generate anywhere from 1 to 64 triangles or subpatches. Statically assigning threads to a fixed size means half of them will be idle on average assuming all sizes are equally…
Let's get into the details of how this integrates with Nanite. We aren’t replacing anything Nanite already does. Nothing is changed about the Nanite data structure or how it is built. We are only adding new stages to the rendering pipeline. Instead of directly rasterizing a cluster’s triangles, those triangles are considered to be patches with a displacement function. As such, depending on their…
There are many different approaches for determining whether and by how much a patch needs to be tessellated. It is important that we don’t create cracks between neighboring patches or subpatches. Many Reyes implementations choose tessellation patterns which do not match and must stitch them together after they are generated. We need something that can be determined purely from the subpatch itself…
Requirements All the original goals of Nanite should apply to our approach here as well. One of them implicitly covers the rest: authoring decisions should have no impact on performance . While not 100% realized, Nanite mostly behaves that way so that principle should be maintained if at all possible. Applied here would mean a run-time tessellated and displaced mesh should render just as fast as…
Nanite Tessellation, aka Nanite Dynamic Tessellation, aka Nanite Dynamic Displacement was the next major feature I worked on after Nanite itself. Initial prototypes started back in 2020, only months after showing Nanite publicly for the first time. UE5 still hadn’t even been released to customers yet. After a couple years of shipping Nanite in things and then a couple of years more of development,…
$$ \newcommand{\vv}{\mathbf{v}} \newcommand{\rv}{\mathbf{r}} \newcommand{\muv}{\boldsymbol\mu} \newcommand{\omegav}{\boldsymbol\omega} \newcommand{\mudotv}{\muv\cdot\vv} $$ What can we use this for? One example of a place where distributions are summed up is in normal map and roughness filtering. Normal and roughness maps are textures describing the distribution of microfacet normals. The normal…
$$ \newcommand{\vv}{\mathbf{v}} \newcommand{\rv}{\mathbf{r}} \newcommand{\muv}{\boldsymbol\mu} \newcommand{\mudotv}{\muv\cdot\vv} $$ A normalized SG has the same equation as the probability distribution function for a von Mises-Fisher (vMF) distribution on the 3 dimensional sphere. This affords us a few more tools and applications to work with. A vMF distribution can be defined for any dimension.…
$$ \newcommand{\vv}{\mathbf{v}} \newcommand{\rv}{\mathbf{r}} \newcommand{\muv}{\boldsymbol\mu} \newcommand{\mudotv}{\muv\cdot\vv} $$ A Spherical Gaussian (SG) is a function of unit vector $\vv$ and is defined as \begin{equation} G(\vv;\muv,\lambda, a) = a e^{\lambda(\mudotv - 1)} \end{equation} where unit vector $\muv$, scalar $\lambda$, and scalar $a$ represent the lobe axis, lobe sharpness, and…
Intro and backstory About 4 years ago now I ran into Spherical Gaussian (SG) math in a few different publications in a row, enough that it triggered the pattern detection in my brain. All were using SGs to approximate specular lobes. I remember feeling very similar 10 years prior when Spherical Harmonics were starting to become all the rage. Back with SH I noticed it fairly early, primarily from…
The big news from Epic at GDC this year was that Unreal Engine 4 is now available to everyone for only $19/month + 5% royalties . There's been a lot said already about why this is cool, opinions, comparisons to competitors and so forth. From a business model point of view I feel it has been covered better than I could possibly say. If you are interested check out Mark Rein's post or hear it from…
When working with HDR values, two troublesome situations often arise. The first happens when one tries to encode an HDR color using an encoding that has a limited range, for instance RGBM. Values outside the range still need to be handled gracefully, ie not clipped. The second happens when an HDR signal is under sampled. One very bright sample can completely dominate the result. In path tracing…
$$ \newcommand{\nv}{\mathbf{n}} \newcommand{\lv}{\mathbf{l}} \newcommand{\vv}{\mathbf{v}} \newcommand{\hv}{\mathbf{h}} \newcommand{\mv}{\mathbf{m}} \newcommand{\rv}{\mathbf{r}} \newcommand{\ndotl}{\nv\cdot\lv} \newcommand{\ndotv}{\nv\cdot\vv} \newcommand{\ndoth}{\nv\cdot\hv} \newcommand{\ndotm}{\nv\cdot\mv} \newcommand{\vdoth}{\vv\cdot\hv} $$ While I worked on our new shading model for UE4 I tried…
I'm resurrecting this blog from the dead. I'm sorry it's been neglected for a year but I've been busy. If you follow me on twitter ( @BrianKaris ) then this probably isn't news, but for those that don't here's an update: A year ago I left Human Head and accepted a position on the rendering team at Epic Games. Since then we made the UE4 Infiltrator demo . I've worked on temporal AA, reflections,…
The system I described last time allowed specular highlights to reach large distances but only requires calculating them on the tiles where they will show up. This is great but it means now we must calculate shadows for these very large distances. Growing the shadow maps to include geometry at a much greater distance is hugely wasteful. Fortunately there is a solution. Before I get to that though…
First off I'm sorry that I haven't updated this blog in so long. Much of what I have wanted to talk about on this blog, but couldn't, was going to be covered in my GDC talk but that was cancelled due to forces outside my control. If you follow me on twitter ( @BrianKaris ) you probably heard all about it. My comments were picked up by the press and quoted in every story about Prey 2 since. That…
It has been a long time since I updated this blog with substantial content but I wanted to point out that Bethesda just released this new screenshot of Prey 2. It's a great shot but it's also a fantastic demonstration of some new graphical features I added to our latest build of the game. First, there's the depth of field in the background which is HDR circular bokeh DOF. Secondly, in the puddles…
First off it's been a very long time since I made a post. Sorry about that. I've found it difficult to come up with subjects to discuss that I both know enough about and am allowed to publicly talk about. For many, personal hobby projects can be the source of subjects to write about but all the at home pet project stuff I do, I do in the HH codebase and check in if it is a success. Personally I…
This entire post turned out to be hogwash. I'm wiping it out to prevent the spread of misinformation. If you are interested in why it's all nonsense see my comment below. Thanks to Sean Barrett for pointing it out. The result of all of this has been positive ignoring the part of me looking extremely foolish. RGBM is more useful than I originally claimed because a larger scale factor can be used or…
Epic released UDK today. It is the next step in their plan to completely dominate the game engine licensing market place. They've been doing a pretty good job of that so far. To all the other companies trying to compete I'd suggest following in their footsteps. The reason I believe they are so successful is because they do everything they can to get the engine out there and in peoples hands. You…
We are hiring! First up, Human Head Studios, where I work, is hiring for basically every department. We are currently staffing up and are looking for talented people. I can't tell you what we are working on but I can say it's awesome and we are doing some very interesting and innovative things on many fronts including technology. The tech department where I am, is developing our own cutting edge…
LogLUV There has been some talk about using LogLUV encoding to store HDR colors in 32 bits by packing it all into a RGBA_8888 target. I won't go into the details as a better explanation than I could give is here . This encoding has the benefit over standard floating point buffers of reducing ROP bandwidth and storage space at the expense of some shader instructions for both encoding and decoding.…
I got a bogus DMCA notice on this post. Google took it down and now I'm putting it back up. I just finished Killzone 2 and it really is graphically impressive. If you are reading this blog then you are interested in graphics which means you owe it to yourself to play this game. The other levels in the game I think are actually more impressive than the one in the demo. The level in the demo was…
Geometry images are one of those ideas so simple you ask yourself "Why didn't I think of this?" I'll admit it isn't the topic of much discussion concerning the "more geometry" problem for the next generation. They work great for compression but they don't inherently solve any of the other problems. Multi-chart geometry images have a complicated zipping procedure that is also invalid if a part is…
There has been a lot of talk lately about the next generation of hardware and how we are going to render things. The primary topic seems to be "How are we going to render a lot more geometry than we can now?" There are two approaches that are getting a lot of attention. The first is subdivision surfaces with displacement maps and the second is voxel ray casting. Here are some others that are…
I just stumbled on this blog the other day that I haven't seen linked in the graphics blog circle so I thought I'd make a point of mentioning it. Chris Evans, a technical artist from Crytek, has a blog . He has just left Crytek to go to ILM and I hope he keeps up the blog as it's full of art and technical topics. His main site also has some good stuff like cryTools, Crytek's suite of max scripts.…