FXPHD – HOU233 – Rendering Fire and Smoke Simulations in Houdini

本课程由视觉特效艺术家 Liam Whitehouse 讲授，介绍了如何渲染使用 Axiom for Houdini 生成的详细火焰和烟雾模拟。

本课程详细介绍了如何对高分辨率 Axiom 烟火模拟进行创造性调整，包括如何调整烟雾的透明度和阴影以及火焰元素的散射光。您将学习如何在 Solaris 和 Karma 中创建和调整烟火和烟雾材料以匹配参考图像，以及如何使用 HDRI 或 Karma Sky Atmosphere 照明系统向场景添加照明以匹配背景板的外观和感觉。

此外，该课程还介绍了如何设置合成团队所需的 AOV、cryptomatte 和深度渲染输出。

第 1 课：模拟中的动画
如何为特定镜头的高分辨率模拟创建自定义动画。在许多镜头中，动画将在烟火模拟中发挥作用，因此您将学习如何通过对设置进行关键帧处理来将特效从 fx 审阅笔记中获取到模拟中，以创建我们想要的结果并对其进行模拟。还介绍了如何使用烟火影响场在特定关键帧上使用 Axiom 推动或拉动模拟。

第 2 课：Pyro Bake 体积
如何设置和调整 Pyro Bake Volume，它具有多种设置，可用于调整烟雾、火焰和通过我们的 pyro 元素散射光线的外观。首先，您将学习如何调整体积烟雾元素的烟雾颜色、不透明度和阴影密度，然后使用散射设置从我们的火焰模拟中添加散射。您将看到如何匹配参考图像，以便随着温度下降，我们的散射的规模和强度在我们的火焰和暗烟之间真实地融合。这些设置将在渲染时延续到我们的 Karma Pyro 材料中。

第 3 课：Karma Pyro 着色器
如何设置 Karma Pyro Shader VOP 节点材质并将其与参考图像匹配。我们将设置烟雾颜色和透明度，并调整阴影密度，以提供与参考图像相似的正确外观。接下来，我们添加散射并拨入，以营造烟雾体积内热量和照明散射的感觉。此外，我们来看看火焰着色器以及分别渲染和模拟火焰和烟雾的优势。

第 4 课：照明
如何为一天中的不同时间和不同环境设置不同的照明场景。课程涵盖如何使用不同的 HDRI 场景设置夜晚、黄昏、中午阴天、中午晴天和日落照明设置，这些场景为我们的资产和烟火模拟带来不同的感觉和颜色。我们还将学习如何使用区域光和 Karma Skylight 系统进行室内照明或 fx 审查转盘。最后，您将学习如何调整灯光的强度并将它们混合在一起以创建逼真的直接和间接值。

第 5 课：渲染设置
如何为我们的烟火和几何图形设置 AOV、Cryptomatte 和深度图像渲染通道，以便合成团队能够最大限度地灵活地调整 Nuke 中的渲染。还介绍了批量渲染设置、分辨率和样本以及去噪，以获得清晰、无噪点的烟火场景渲染，以供 fx 审查和合成。

Duration 3h 1m MP4

Title: FXPHD – HOU233 – Rendering Fire and Smoke Simulations in Houdini

Info:
This course, from VFX artist Liam Whitehouse, covers how to render detailed fire and smoke simulations which have been generated using Axiom for Houdini.

This course looks in detail at how to make creative adjustments to high resolution Axiom pyro simulations, including how to adjust the transparency and shadowing of smoke and the lighting scattering from fire elements. You will learn how to create and adjust pyro fire and smoke materials in Solaris and Karma to match reference imagery and how to add lighting to the scene to match the look and feel of background plates using HDRI or the Karma Sky Atmosphere lighting system.

In addition, the course covers how to setup AOV’s, cryptomattes, and deep render outputs that are ready for the compositing team.

Class 1: Animation in simulations
How to create custom animation for high resolution simulations for specific shots. In many shots animation will play a part in pyro simulations so you will learn how to get an effect from fx review notes into a simulation by key framing the settings to create our desired outcome and simulate it. Also covered is how to use pyro influence fields to push or pull simulations with Axiom on specific keyframes.

Class 2: Pyro Bake Volume
How to setup and adjust the Pyro Bake Volume which has a myriad of settings to adjust the look and appearance of both the smoke, fire, and scattering of light through our pyro element. First, you will learn how to adjust the smoke colour, opacity and shadow density of the volumetric smoke elements and then add scattering through the volume from our fire simulation using the scatter settings. You will see how to match reference imagery so that the scale and intensity of our scattering blends realistically between our fire and our dark smoke as the temperature cools down. These settings will carry across into our Karma Pyro materials at render time.

Class 3: Karma Pyro Shader
How to setup the Karma Pyro Shader VOP node materials and match them to reference imagery. We will setup our smoke colour and transparency and adjust our shadow density to give the correct look which is similar to the reference. Next, we add scattering and dial it in to give the feeling of heat and illumination scattering inside our smoke volume. Also, a look at the fire shader and the advantages of having fire and smoke separately rendered and simulated.

Class 4: Lighting
How to setup different lighting scenarios for different times of day and different environments. The class covers how to setup night, dusk, midday cloudy, midday sunny, and sunset lighting setups using different HDRI scenes that give us a different feel and colours on our asset and pyro simulation. We will also learn how to use area lights and the Karma Skylight system for interior lighting or fx review turntables. Finally, you will learn how to adjust the intensity of lights and mix and blend them together to create realistic direct and indirect values.

Class 5: Render setup
How to setup AOV’s, Cryptomattes and deep image render passes for our pyro and geometry so that the comp team can has maximum flexibility to adjust the renders in Nuke. Also covered are batch render settings, resolution and samples, and denoising to get sharp, noise-free renders of our pyro scene for fx review and compositing.