FXPHD – HOU116 – Height Fields in Houdini, Part 2

Houdini 高度字段有许多有用的节点，可以快速创建可在 Houdini 中使用或与置换贴图一起导出的逼真地形。您可以模拟喷发、隔离区域以产生水以及许多其他地形条件。这门由 Charles Chorein 教授的两部分课程将帮助您快速使用 Houdini 中的功能。

本课程是二人组的第二部分，重点介绍 Mantra 方面的着色、照明、渲染和其他技术方面，以使我们能够渲染这个镜头。它包括探索 Mantra 中用于去噪渲染的 NVIDIA OptiX 技术，以及使用 LPE 和实用 AOV 来帮助在 Nuke 中创建合成。

课程1：LPES 和 OPTIX
本课程首先创建带有纹理的雪和树着色器。对光路表达式 (LPE) 的探索，它为我们在 Nuke 中的 AOV 提供了额外的控制层，而无需一行代码。最后，对于那些拥有 NVIDIA 显卡的人，如何在 Mantra 中使用 NVIDIA 的 OptiX 技术来使用 GPU 对渲染进行去噪。
第 2 类：处理噪声
样本和噪声可能非常耗时且难以处理。Mantra 提供了很多控制来优化和获得无噪声渲染的正确值。本课程包括探索多个测试以检查可能性并获得正确的设置。
第三类：照明
既然我们场景的所有技术方面都已得到解决，我们将努力尽可能地匹配图像参考，以便将山脉融入背景中。分析背景图像中的照明以及如何使用 HDRI、SkyLight 和 AreaLight 重新创建它。
第 4 类：渲染前的最后步骤
在启动最终渲染之前，我们添加了额外的 AOV，这将使我们能够直接在 Nuke 中调整和重新平衡我们的图像和照明，而无需重新渲染。不要低估 Houdini Mantra 中的 Cryptomatte ……它的设置非常简单，并且在 Nuke 中用于创建面具非常有用。
第 5 类：SLAP COMP
渲染完成后，我们通过 Alembic 文件在 Houdini 中导出相机，并在 Nuke 中重新创建 3D 设置以匹配相机移动。在 Nuke 中创建一个 slap comp，使用我们的 AOV、Cryptomatte 和多光源重新平衡图像，以改进和完成该 comp。

Duration 1h 57m Project Files Included MP4

Title: FXPHD – HOU116 – Height Fields in Houdini, Part 2

Info:
Houdini height fields have many useful nodes to be able to quickly create a realistic terrain which can be use in Houdini or exported with a displacement map. You can simulation eruption, isolate areas to create water, and many other terrain conditions. This two part course, taught by Charles Chorein, will get you up to speed on using the features in Houdini.

This course, part two of the duo, focuses on shading, lighting, rendering, and other technical aspects of Mantra aspect to enable us to render this shot. It includes an exploration of NVIDIA OptiX technology in Mantra for denoising renders, as well as the use of LPEs,and utility AOVs to help in creating the composite in Nuke.

CLASS 1: LPES AND OPTIX
The course begins by creating a snow and tree shader with textures. An exploration of Light Path Expressions (LPEs), which provide extra layers of control for our AOVs in Nuke without a single line of coding. Finally, for those with an NVIDIA graphics card, how to use NVIDIA’s OptiX technology in Mantra to denoise renders on the fly using the GPU.
CLASS 2: DEALING WITH NOISE
Samples and noise can be time-consuming and difficult to handle. Mantra provides a lot of control to optimize and get the right values for noise-free renders. This class includes an exploration of multiple tests to examine the possibilities and obtain the right settings.
CLASS 3: LIGHTING
Now that all technical aspects of our scene have been addressed, we work towards matching the image reference as closely as possible in order to integrate the mountain into the background. An analysis of the lighting in the background image and how to re-create it with an HDRI, SkyLight and AreaLight.
CLASS 4: FINAL STEPS BEFORE RENDERING
Before launching our final render, we add additional AOVs which will allow us to be able to adjust and rebalance our image and lighting directly in Nuke without re-rendering. Don’t under estimate Cryptomatte in Houdini Mantra….it’s very simple to set up and extremely useful in Nuke for creating masks.
CLASS 5: SLAP COMP
With the renders complete, we export the camera in Houdini via an Alembic file and re-create the 3D setup in Nuke in order to match the camera movement. Creation of a slap comp in Nuke, rebalancing the image using ourAOVs, Cryptomatte, and multilights inorder to improve and finish the comp.