Max Liani @maxliani Twitter profile

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Max Liani

@maxliani

1 month

How many indirect bounces? 0, 1, 2... 1000?

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Max Liani

@maxliani

3 years

A fascinating Moiré pattern forms when I scale down these 100k cubes.

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Max Liani

@maxliani

3 years

My theory is that the hexagonal storm at the pole of planet Saturn is due to the UV interpolation around an extraordinary vertex in a Catmull-Clark subdivision surface...

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Max Liani

@maxliani

1 year

Spot area lights can be tricky to implement because they don't have a simple physical meaning (condensers, reflectors, shutters, barndoors... they all act in a very different way). However, decent basic controls are fundamental to give artistic control over lighting.

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Max Liani

@maxliani

7 years

I know C++

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Max Liani

@maxliani

1 year

... lots of work to be done 😅

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Max Liani

@maxliani

1 year

Some renderers take the simplification to compute Fresnel on the surface normal, instead of using the microgeometry. Done wrong, that makes high roughness look velvety, requiring some funky f0-f90 controls. This is what that looks like.

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Max Liani

@maxliani

1 year

I am expanding what the pixel inspector can do, now capturing and visualizing light paths contributing to the pixel. The scattered paths are in yellow, NEE in red.

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Max Liani

@maxliani

1 year

Hello caustics 😊

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Max Liani

@maxliani

1 year

Today I finally pipelined the denoiser to the path tracer. It is expensive to run, around 15ms/frame, so I have work to do!! I feel the result is cool nonetheless! Denoising indirect illumination, caustics, and all ☺️

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Max Liani

@maxliani

2 years

I replaced a complex data structure with a flat vector, and changed the algorithm to work with it. Result is twice as fast and uses about 1/3 of the memory. Never underestimate the effectiveness of simplicity.

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Max Liani

@maxliani

1 year

The denoiser work is done! It works better than I hoped for. It is impossible to tell the difference between fp32 and fp16. It looks like nothing changes in the image, except that one takes half the time than the other, and at 7.1ms I can have the denoiser on by default.

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Max Liani

@maxliani

1 year

Sooooo smoooooth... I think this is done. Moving on!

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Max Liani

@maxliani

7 months

The weekend is over. I implemented an analytic ring light. The math is simple, I'll post some notes about it.

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Max Liani

@maxliani

1 year

This is not true. Raytracing was introduced in RenderMan 11 in 2003, here is the release notes: Personally I used raytracing rather extensively starting from Happy Feet between 2005 and 2006.

Documentation

renderman.pixar.com

AMDGPU

@AMDGPU_

1 year

No raytracing was used in renderman until 2013. Some movies used shader techniques in specific spots similar to raytracing. Quote from Pixar technical director Chris Horne from 2013

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Max Liani

@maxliani

1 year

Hello Fresnel

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Max Liani

@maxliani

1 year

Ah, the amount of pain people endure these days to avoid writing a for loop

Andreas Longva

@andreas_longva

1 year

Can you spot the undefined behavior? Back to doing some C++ with Eigen. Just wanted to transform some points, and this one had me scratching my head for a while. Solution in next tweet (thanks to my colleague @w1th0utnam3 for pointing out the problem!) 🧵 1/4

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Max Liani

@maxliani

7 months

I posted about this a while ago: sometimes you want to scale a light and adjust its luminosity, bigger light means brighter illumination; sometimes you like the luminosity, but you want to change the softness of the shadows. You need two ways to scale a light.

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Max Liani

@maxliani

2 years

Ray traversal on the BVH works, so... hum... I don't know... Enjoy 40 million cubes, I guess.

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Max Liani

@maxliani

7 months

Second round on the ring light. It now has a hole in the middle 😉.

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Max Liani

@maxliani

7 months

Shades of gray in the shadow penumbra aren't always appealing: a tinge of red or blue can help express warmth or cold and help convey the emotion in a shot. A light control to produce color fringes without having to paint emission textures can be useful.

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Max Liani

@maxliani

1 year

The heebie jeebies of when you spot things moving in the dark...

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Max Liani

@maxliani

4 years

I am proud to announce I will be joining the NVIDIA family!

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Max Liani

@maxliani

9 months

I spent a few hours working on memory pools and now I can handle a hefty amount of unique geometries. Here are 1 million unique cubes where for each I jittered points and colors. The biggest bottleneck is building 1 million tiny BLASs.

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Max Liani

@maxliani

1 year

It had been a long flight but I am glad to be in Australia again!

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Max Liani

@maxliani

2 months

First super-naive implementation of texturing is done. From here, it can only get better! :D

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Max Liani

@maxliani

3 months

Amazon delivery arrived, apparently it got shipped as a 2-level BVH.

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Max Liani

@maxliani

2 years

When I was a lighter I rarely wanted to deal with radiometric quantities: set some value representing the radiant intensity, set the size... Often you change the size of the light to control the softness of its shadows, not the power; so, you need two ways to scale a light

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Max Liani

@maxliani

2 years

Ok, enough for today, the weekend is over. I have a basic top-down 2-ways binned SAH BVH builder. I'll get more complex when I parallelize it and add support of higher branching factors. For now it's 176 lines of code (including comments and debug draw)

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Max Liani

@maxliani

1 year

Fixed some fireflies, improved numerical robustness. Using the correct Fresnel equation, one can set IOR=1 to disable the dielectric interface, and only render the substratum. Perhaps trickier to texture, but physically grounded, instead of some arbitrary "specular weight".

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Max Liani

@maxliani

4 years

I am currently mentoring no one. If you have questions or need some support in learning, hit me up. I mentor for free. For tech people: C++, raytracing, fundamentals of light transport... For artists: how to approach lighting, tips to develop you skills, how to interview...

Max Liani

@maxliani

7 years

To students and junior programmers and 3D artists. A reminder that I'm here to answer some of your questions. C/C++, low level coding, etc..

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Max Liani

@maxliani

3 years

I'm cleaning up my undo system. In preparation of a blog post, I decided to write a guideline to help designing an application that supports undo.

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Max Liani

@maxliani

9 months

Day of debugging at work. So, to end the night with something quick and fun. Here are thousands of dragons ready to pounce!

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Max Liani

@maxliani

1 year

I have been buried in tensors for the last couple of weekends and I am coming out for air... Still lots to do, learning a ton in the process! This is what I have been working on:

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Max Liani

@maxliani

2 years

WIP modular BVH traversal implementation

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Max Liani

@maxliani

1 year

A primordial pixel inspector tool to isolate samples and see noise in its full glory!

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Max Liani

@maxliani

1 year

Last day of winter break. I added basic support for elliptical lights. Also added single/double-side emission, and light exposure when visible to camera (which makes the light invisible to primary rays when set to zero).

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Max Liani

@maxliani

1 year

I am working on a blog mini series about my recent dive in denoising with deep neural networks. I am no expert, but stay tuned if you are interested.

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Max Liani

@maxliani

1 year

Second iteration at visualizing paths. Added a filter to exclude noncontributing paths, plus an interactive selection to isolate a single path and see more details about it.

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Max Liani

@maxliani

2 months

New blog post: fast, single kernel 2D CDF construction (for HDR light maps importance sampling)

About fast 2D CDF construction

In a path tracer, sampling a light source that is driven by a texture, such as a HDR map, requires mapping a 2d random number to texels of the map, with a probability that is proportional to the br…

maxliani.wordpress.com

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Max Liani

@maxliani

4 years

If you have 50 minutes to spare, check our GTC talk about production rendering on CPUs and GPUs:

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Max Liani

@maxliani

3 years

Rotation manipulators are tricky. I have chosen a less conventional approach for this one: instead of circling around the mouse, which isn't natural, manipulation is constrained along the tangent of where you click (check the line). I find this more intuitive. What do you think?

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Max Liani

@maxliani

8 months

I made some improvements in how I present subdivision surfaces wireframe. I am still tinkering on how this should be polished, but I feel this is step in the right direction. Sooner or later, I'll have to go back and write myself a few modeling operators, and their manipulators.

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Max Liani

@maxliani

1 year

The raytracing elevator

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Max Liani

@maxliani

27 days

First draft adoption of imgui docking is working. Edits on my side made it tricky to get "captionless" windows and imgui viewport to coexist. There is still a lot I'd need to polish. Docking is black magic, so much code in the backend! Kudos to @ocornut for pulling that off!

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Max Liani

@maxliani

3 years

This is every software engineer dealing with poorly documented API methods.

Comrade Phteven

@PhriendlyCody

3 years

ive literally been laughing for an hour now

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Max Liani

@maxliani

1 year

Some rough surfaces with a matte finishing exhibit sharp reflection at a glancing angle. Not something current microfacet models do well. I am toying around a "polish" parameter to give control over that. Here is an experiment.

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Max Liani

@maxliani

2 years

Visualizing BVH SAH split logic. I wish I had this level of convenience when I implemented my first, or second... or third production renderer.

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Max Liani

@maxliani

3 years

New blog post: Gesture::Graphics, an junior level introduction to the infrastructure for drawing manipulators and GUI widgets in a 3d editor.

Offline to Realtime: Gesture Graphics

Today I am writing about the second part of Gesture, the graphics component that allows me to draw on screen. Gesture::Graphics is not meant to draw a 3d scene, it is rather some infrastructure for…

maxliani.wordpress.com

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Max Liani

@maxliani

3 years

Super cool kids: some cool neural application in realtime light transport simulation... Me: new blog post on viewport manipulators...

Offline to Realtime: Manipulators

In my new system design I allow to draw anything and give free range of what a manipulator may be and how it may behave. The infrastructure in Gesture::Input and Gesture::Graphics comes together to…

maxliani.wordpress.com

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Max Liani

@maxliani

1 year

New blog post! Episode 1 of a new mini-series about my recent dive into Denoising DNN.

DNND 1: a Deep Neural Network Dive

This is the first episode of a mini-series where I invite you to join me on a journey of discovery in the vast world of Deep Neural Networks. We will be exploring the Deep Neural Network in the Int…

maxliani.wordpress.com

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Max Liani

@maxliani

1 year

It's Friday! New blog post: DNND episode 2, tensors and convolution

DNND 2: Tensors and Convolution

This is the second episode of a miniseries in the vast world of Deep Neural Networks, where I start from Intel® Open Image Denoise open-source library (OIDN) and create a CUDA/CUDNN-based denoiser …

maxliani.wordpress.com

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Max Liani

@maxliani

8 months

It's not light transport without the hacks.

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Max Liani

@maxliani

1 year

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Max Liani

@maxliani

3 years

We all do this:

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Max Liani

@maxliani

2 months

If you can texture albedo, you can texture roughness! Though, the denoiser may not like it... 😜

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Max Liani

@maxliani

9 months

Selection got fast!!!

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Max Liani

@maxliani

1 year

This is supposed to be a denoiser... but apparently it likes to make pastel paintings instead...

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Max Liani

@maxliani

3 years

printf on the GPU is all you need.

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Max Liani

@maxliani

3 years

Ok, this is not much, but from writing nothing, to writing something, it is a progress.

Offline to Realtime: the beginning of a journey

I feel I am far from home right now. For the longest time I cut my teeth on movies. Doing lighting, writing tools, writing rendering tech. It grew up very familiar, that type of familiar where inst…

maxliani.wordpress.com

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Max Liani

@maxliani

7 months

To me, native visualization tools are key for a speedy development cycle! By native I mean "inside the application". For example, this is the importance sampling visualization for the light controls I posted yesterday:

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Max Liani

@maxliani

1 year

I improved the light path visualization to better resemble those cute diagrams you find in light transport papers. 🥰

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Max Liani

@maxliani

9 months

Untitled

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Max Liani

@maxliani

3 years

Proof: if Saturn was a NURBS sphere, the storm would be concentric 😇

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Max Liani

@maxliani

1 year

After nearly two years, I implemented the sphere in my project! Backward way of working in graphics... Typically, in a raytracer the sphere is the first thing you ever render. Don't worry about the fireflies: I still need to implemented path regularization.

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Max Liani

@maxliani

3 years

This experiment is a a little nuts: non linear undo. Basically, if you undo some stuff and and them make some changes, that state forks into another "parallel reality". You can then jump between any step across the forking paths to continue where you left off, or fork further

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Max Liani

@maxliani

9 months

Random doddle.

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Max Liani

@maxliani

1 year

Ok, ok... last one

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Max Liani

@maxliani

8 months

This is the last post in a series about scene graph optimizations. In the video, each of the cubes of cubes is a little over 1/4 million transforms. Duplicating, manipulating that mass of nodes seems to be not possible in most DCCs. 🧵1/4

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Max Liani

@maxliani

2 years

Friday night drinks, while looking at a BVH rebuilding, AABBs dancing.

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Max Liani

@maxliani

9 months

Alright, alright. I took a quick pass of redemption, after posting the wrong polycount yesterday. Here are your complementary 15,641,810,018,304 triangles. Point in case, instancing alone doesn't make a good demo, not unless you want to make dragons' dust.

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Max Liani

@maxliani

10 months

I parallelized the startup sequence, now it takes about 800ms for Workbench to boot up and be ready to use. cudnn takes longer than that, so the denoiser won't kick in until a couple of seconds later. You can see it in this video. The operation is seamless.

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Max Liani

@maxliani

3 years

This "thing" is beginning to look like an actual 3d editor. I need a file format... I need to implement a file format / scene IO... it's going to be a lot of work...

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Max Liani

@maxliani

3 years

VisualStudio trying to replace “,=“ with “ =“ on a 250 lines source file… It’s been going on for minutes… FFS!!

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Max Liani

@maxliani

1 year

New blog post! DNND 3: the U-Net architecture. In the post I deconstruct the DNN architecture used in the OIDN denoiser to process path tracing rendering. #MachineLearning #AI

DNND 3: the U-Net Architecture

This is episode three of a miniseries on the vast world of Deep Neural Networks. I start by exploring the Intel® Open Image Denoise open-source library (OIDN) and create a CUDA/CUDNN-based denoiser…

maxliani.wordpress.com

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Max Liani

@maxliani

7 years

To students and junior programmers and 3D artists. A reminder that I'm here to answer some of your questions. C/C++, low level coding, etc..

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Max Liani

@maxliani

9 months

Here is a clip showing the light rig for the scene:

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Max Liani

@maxliani

1 year

Second iteration on the look of the pixel inspector. I really need text rendering...

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Max Liani

@maxliani

8 months

Just for giggles, comparison Workbench vs Maya

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Max Liani

@maxliani

2 years

Look, I have a thread scheduler 😊 While minimalist, here are a few things it can do:

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Max Liani

@maxliani

3 years

My turn: SDF, subdivision surface, NURBS, triangles

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Max Liani

@maxliani

7 years

First attempt to teach my daughter how computers work:

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Max Liani

@maxliani

3 years

And some procedural animation. Here are about 100,000 cubes.

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Max Liani

@maxliani

10 months

With so many graphics people leaving the platform, I wonder how many are still here. I try to compartmentalize, and not let one thing poison another. I’ll keep on posting in a positive spirit.

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Max Liani

@maxliani

1 year

@AMDGPU_ Most of the shots you show in that demo reel have been fully path traced 🤔 I contributed to some of those movies myself…

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Max Liani

@maxliani

1 year

The old trick of raytracing parallel mirrors never gets old

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Max Liani

@maxliani

3 months

So… here is the problem with occasional gaming: by the time the forced update completes, my free time to spend gaming is gone and I moved on doing other stuff…

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Max Liani

@maxliani

4 months

First screen recording of the year! Let's see if I can get back in the rhythm...😁 This is a weird one! (just to test rebuilding the dome light CDF per frame)

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Max Liani

@maxliani

9 months

Ok, last offer... slightly faster than before, with twice as much stuff. 20 million cubes... last offer! PS: if you are curious about the scene hierarchy, check the last few seconds of the video.

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Max Liani

@maxliani

2 years

It wasn't planned, but I gave a shot at improving the selection wireframe on the path tracer. I feel it tuned out pretty sleek, and it was simpler to implement than I anticipated.

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Max Liani

@maxliani

2 years

At which point do you call it a path tracer? Is indirect diffuse enough? I am counting on Twitter's denoiser to make it look good... 😊 Anyway, time is up for today. I didn't originally plan to work on this on my day off.

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Max Liani

@maxliani

2 years

There we go, I have a super naïve raytracer running on a single thread on the CPU. Not a bad start, but clearly a monumental amount of work left to do :D In the video I start with the rasterizer view and switch to raytracing (looks the same for now, modulo aliasing and the grid)

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Max Liani

@maxliani

21 days

Improved panels alignment. Now, inactive resize bars and the frame around the render viewport are consistent. I believe it gives a small touch of elegance and solidity. Everything can be hidden, leaving just a massive viewport.

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Max Liani

@maxliani

1 year

I had another go at optimizing my pooling and resampling kernels; convolution is still from cudnn. Now the denoiser runs in 5.5ms. 🍻

Max Liani

@maxliani

1 year

The denoiser work is done! It works better than I hoped for. It is impossible to tell the difference between fp32 and fp16. It looks like nothing changes in the image, except that one takes half the time than the other, and at 7.1ms I can have the denoiser on by default.

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Max Liani

@maxliani

2 years

New blog post: Anatomy of a task scheduler

Anatomy of a task scheduler

In designing a task scheduler, it is fundamental to consider how it would impact your code. I find that some articles on tasking systems put emphasis on the innerworkings, how to achieve lightweigh…

maxliani.wordpress.com

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Max Liani

@maxliani

1 year

I finally got myself one of these M2 Max thingy! Replacing a 2012 unit :)

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Max Liani

@maxliani

3 years

Scene graph update. 100,000 objects grouped as 100 top level groups containing 1000 cubes each. A procedural animation moves 15 of those top level groups, which propagates xform update to 15,000 objects. The scene graph updates per frame only what changed.

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Max Liani

@maxliani

9 months

10 million transforms. Kinda slow... still, usable.

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Max Liani

@maxliani

3 years

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Max Liani

@maxliani

4 years

@Nothke @cmuratori Beginner programmer: flat array using std::vector Intermediate programmer: complex data structure using custom templates containers and allocators Expert programmer: flat array using malloc.

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