Houdini 19.5 Solaris

LOPs for lighting tutorials

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Welcome to the LOPs Lighting Tutorial series. Houdini’s tooling and support for USD is collectively known as Solaris. Solaris includes USD support in the view and a new network type, LOPs (Light Operators). LOP networks are similar to SOPs, where each node accepts incoming geometry, modifies it, and outputs new geometry. In LOPs, each node accepts an incoming USD scene, modifies it, and outputs a new scene. LOPs also features Houdini’s new renderer, Karma, which consumes usd instead of ifd, which mantra consumed. The LOPs context features many new enhancements to make lighting faster and more efficient.

Download the support files

You will need to download the necessary support files (~284 MB).

Once you have downloaded the files, you will need to unarchive them. Depending on your operating system, this might be as simple as double clicking on the file.

The files should be stored in $HIP. As you might know, $HIP within Houdini means “where you launched Houdini.” So if you are planning on storing your hip files for these tutorials in $HOME/projects/LOPS then you should put the downloaded files in the same place.

In the downloaded files you will see Houdinis file called “tutorial-lighting-end.hip”, “tutorial-lighting-start.1.hip” and a directory called “BarScene”. Before you launch Houdini, move the two hip files up one level in your directory tree.

A few things to know before you begin

This tutorial series features assets which have been marshaled into LOPs via the Stage Manager. The Stage Manager imports USD prims into LOPs via usd files. If you do not have your assets saved out as usd files, you can either import directly from SOPs via the Scene Import (for entire scenes), or via the SOP Import (for individual objects/SOPs). New geometry can be created in LOPs directly though the SOP Create LOP.


These are the tutorials that will walk you through using LOPS/USD in a typical pipeline.

  • LOPs for lighting - Tutorial 1

    In the first tutorial, you will open and explore the example LOPs scene file, create a point light and a new camera, make a few adjustments to LOPs and render properties and settings, and produce a test render.

  • LOPs for lighting - Tutorial 2

    Continuing from the previous tutorial, you will light your LOPs scene.

  • LOPs for lighting - Tutorial 3

    You will continue to tweak your lighting, organize your lights, and then render your scene.




  • Importing SOP geometry into USD

    Details of how Houdini converts SOP geometry to USD, and how you can control the process.

  • Component Builder

    The Component Builder tool puts down a network snippet for creating a USD model from SOPs, with support for materials, variants, payloads, and layering.


  • Edit node

    Interactively transforms prims in the viewer. Can use physics collisions to position props realistically.

  • Layout node

    Provides tools for populating a scene with instanced USD assets. You can place individual components, paint/scatter components in different ways using customizable brushes, and edit existing instances.

  • Custom Layout Brushes

    How to create layout brush digital assets you can use to customize the behavior of the Layout LOP.


  • Shader Framework

    Describes the Solaris shading framework, including shader node translation to USD primitives.

  • Using MaterialX in Solaris

    Houdini has VOP node equivalents of the MaterialX shader nodes. You can build a shader network using these nodes, or import an existing MaterialX shader, and use them with Karma (Houdini’s USD renderer).

  • UDIM

    You can encode different tiles of a texture space into different texture files, each with its own resolution. You can then specify a texture filename such as kaiju.exr, and Houdini will replace the token with the specific tile address at load time.

Karma rendering