Sort edge indices so their order is always the same (if there are AB and BA, they both become AB), as it will speed up comparisons. The whole point of tracing the bitmask and dilating these spots inside is to minimize shadow leaking in mips, while not affecting the original texture. Adjusting sample positions is a massive improvement: And another comparison, before and after: Next thing to address is the wrong self-shadowing of smooth low-poly surfaces. Therefore skylight and GI have independent sample counts, and I usually set more for the sky. I am working on a GPU lightmapper now, I try to bake single lightmap for the highest LOD,and mapped it to other LODs. Attempting to push it behind more distant faces with leave the texel incorrectly shadowed. If a triangle was too small to be drawn, and if you dilate nearby texels over its supposed place, you will get artifacts. Wrapping it up the complete algorithm is: In general, lightmaps are best left without mip-mapping. I’ll go over each of these problems one by one. First all lights are blended additively, then GI bounces everything. In all offline renderers I know preconvolved/lowres HDRIs produce much better results with less sample counts than hi-res. Thanks for your reply.I think you can read this enlighten lightmap trick.I implemented this trick and the result is not bad,and my lightmapper is much faster than before,because there is no need to generate LOD lightmaps. I can't build light in certain scenes. Anyway, in this article I’m writing from OptiX/CUDA (ray-tracing) and DX11 (tools) perspective.

But anyway back to tech, I never even hoped that lightmaps could be clean on a model like Alix, it’s like you did “nobody told me it was impossible so I did it”.

Is it possible to use the lightmaps (and vertex colors, I would definitely use that feature) that this program bakes for other engines than Unity? An obvious consequence of moving sample positions too far from the surface is that they now can go inside another surface! Let’s say, you have a simple lighting shader, and a mesh with lightmap UVs: You want to bake this lighting, how do you that? Having rays not aligned to UV direction can produce some undershoots and overshoots: In the end I simply chose to stay with a small overshoot. Tweaking the value for one spot breaks the shadow on another: Blurring the result will mess with desired shadow width and proper lighting gradients, so it’s a bad idea. Such offset is often needed in ray-tracing. Did Epic hire you because of the lightmapper?

A popular approach is to supersample the lightmap, calculating multiple lighting values inside one texel area and then averaging. Ideally you may want 2 separate values for non-square texels, but it’s not common for lightmaps, as all automatic unwrappers try to avoid heavy distortion. Unfortunately I don’t have a working code of this implementation anymore, but I remember it was pretty bad. I have to split different LODs into different lightmap atlases so I can launch lightmapping kernels for them separately with different scene geometry. Previously OptiX denoiser was only trained on non-HDR data (although input/output is float3). The first step I would recommend would be to turn off your sun and get your lighting right using just skylight. Press J to jump to the feed. OptiX was the first of such kind, and that is why I chose it for Bakery, as there were no alternatives back in the day. But because of floats being floats, the further object is getting from the world origin, the less accuracy we get for coordinates. Press question mark to learn the rest of the keyboard shortcuts. The sun is incredibly bright compared to even its reflected light, so patches of direct sunlight will be blown out with the rest of the scene dark. Check “How do I share a scene with someone who doesn’t have Bakery installed?” question. What are you ray traversal secrets? The code I wrote for it is terribly inefficient and was the result of quick experimentation, but it gets the job done, and we only need to execute it once before any lightmap rendering: Most of these matrix multiplies could be replaced by something cheaper, but anyway, here’s the result: The seam is gone.

however,this method yield many artifacts,because of the unreliable mapping function…. I’m wondering somehow to combine the two parts so we can have the best lightmapper in the world lol.

The shadow is still having somewhat weird shape, but in fact it looks exactly like that even when using classic shadowmapping, so I call it a day. Brute force search can be terribly slow. Thanks in advance to everyone for their help, tips, information etc :). Note that none of the APIs generate lighting, but they only give you a very flexible way of fast ray-primitive intersection on the GPU, and there are potentially lots of different ways to (ab)use it. Hello Mr F, Thanks for your post, I am writing a lightmapper for our custom engine using DXR, and this post helped me a lot to get rid of all those ugly artifacts.

They can create rays, trace them by executing and waiting for intersection/hit programs (also new shader types) and then obtain the result. Ray bias [GPU] Draw lines on top of the lightmap. Adding constant bias to ray start (used in many offline renderers), Making shadow rays ignore adjacent faces that are almost coplanar (used in 3dsmax in “Advanced Ray-Traced Shadow” mode), Tessellating/smoothing geometry before ray-tracing (mentioned somewhere), Blurring the result (mentioned somewhere), Trace a ray from flat position to smooth position, If there is an obstacle, use flat, otherwise smooth.

It’s a balance between wrong self-shadowing and peter-panning: Shadow ray bias demonstration from 3dsmax documentation. Enter your email address to follow this blog and receive notifications of new posts by email. If ray hits a backface, this texel will leak. Learn more, We use analytics cookies to understand how you use our websites so we can make them better, e.g.

I heard it’s not the case today, but even with this limitation, it’s still very usable.

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Asset store allows doing that, but nobody did. Even given some imperfections, I think the quality is quite good for most cases and simple to understand/implement comparing to least squares. The trick is to use a reversible tonemapping operator, here is a. the guy is refunding I don’t get why. Sorting the destination hits is also good, especially when you have complex materials to evaluate as the paper points out, but in our lightmapping case it isn’t very useful.

I also encountered all of your problems in my lightmapper, even the shadow terminator in a different context though, I thought there were no solution. In my old tweet I promised to write about how it works, as there were many, MANY unexpected problems on the way, and I think such write-up would be useful. Why is it so bad?

Can we place samples as they were on a round object, not a faceted one? Calculating lighting for every GBuffer texel and dilating the result looks horrible, and there are many artifacts: What have we done? But then my genius friend Boris comes in and says: Wait, is that it? The proposed idea was to utilize least squares to make texels from different sides of the seam match. Alpha channels also contain interesting things like world-space texel size and triangle ID. It’s a shame, because it could produce an almost meaningful extruded position, but instead goes inside and we have to flatten it.

“Ray generation program” is a term used in both OptiX and DXR – think of it as a compute shader with additional ray-tracing capabilities.

[CPU] Find seams and create a line vertex buffer with them. We use optional third-party analytics cookies to understand how you use so we can build better products. GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together. Change ), You are commenting using your Google account.

In accordance with the art. Here it shows triangles marked by the algorithm above: Note how there are especially many triangles marked in the area of belt/body intersection, where both surfaces are smooth-shaded. UV layouts are often imperfect and can contain very small triangles that will be simply skipped or rendered with noticeable aliasing.

Currently, not all GPUs support real conservative raster (hey, I’m not sponsored by Nvidia, just saying), but there are multiple ways to achieve similar results without it: Repurposing MSAA samples is a fun idea. Been looking for an alternative to Lightmass in UE for a long time, and the way I am making my art will support external lightmaps. My main problem is that the parts of the interior where the sun hits are extremely bright, while the other parts of the interior are not as bright as they should be. Bonus: mip-mapping lightmaps.

To overcome this you need to balance the amount of sunlight with skylight and possibly interior lighting.

I use the same GBuffer idea – UE4’s default Lightmass also, but it does CPU software rasterization.

It’s finally done, and you can even buy it on Unity’s Asset Store (it can be used outside of Unity as well, but the demand is higher there). A community with content by developers, for developers! Is it possible to load the baked light maps without adding bakery plugin in the new project? May I ask how do you deal with LOD objects, just bake N lightmap for N LOD?

Eye adaption off. The more traditional style sorting is this – SBVH is still the best one for speed – and since embree has provided helper API that lets you build SBVH with any branching factor very quickly. Cookies help us deliver our Services.

The best place to discuss problems like this is the official forum:, In your case, please read the FAQ: However then I learnt that people never use it alone.

Consider this case: Only 2 shortest rays will properly push the sample out, giving it similar color to its surroundings. Here is an illustration of how it works: Here is a 4 rays loop. If i increase it, the sun is unrealistically bright (the part of the mesh where the direct light hits is literally completely white, you can't even see the texture). The major focus of this project was to minimize any kinds of artifacts lightmapping often produces, like seams and leaks, and also make it flexible and fast.

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