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In this series of tutorials, we are going to go through a typical production pipeline using LOPs. Most large studios have a pipeline that tries to non-destructively layer accumulated changes from contributing departments to create a final result.
For example, the assets department will create assets for an entire project. The layout department will load these assets in a sequence layout, and then modify this layout for individual shot layouts. Let’s also say the layout department puts un-animated characters in the scene as blocking. We also want the layout department to render these blocked-out scenes with sequence lighting and the tracked camera for dailies and approvals.
Next, for an individual shot, an animator will load the approved layout, and animate the characters. Now we want the animated characters to replace the still characters the layout department put in place.
In this case, the animation will be layered into the existing scene, (“stage” in USD/LOPs speak). Thus the scene is non-destructively modified. If we want to, we can “mute” the animation layer and see the scene without the character animation.
After this, let’s say the shot goes to FX. The FX department will prune out the parts of the scene they need to modify. Once modified, they will publish their results as a USD layer. In the composed stage, (the result of layering the FX changes onto the existing USD stage), the FX layer is stronger than the previous layers, and will layer “over” the existing prims (USD/LOPs speak for objects). Again, if an artist wants to see the scene without the FX layer, they can “mute” it. Nothing is ever destroyed in USD (as it may be used by other departments or processes).
Finally, lighting gets the scene. They can “mute” all temp lights, and/or “unmute” the sequence lighting. Now they can move the lights around and add new lights to customize the scene. If the scene is too heavy, they can “mute,” for example, the FX layer until the lighting is finalized.
These layering and muting abilities make USD/LOPs an incredibly powerful and useful pipeline tool. In this series of tutorials, we will be stepping through a (simplified) production pipeline department by department to see how LOPs can be used to aid in your production pipeline.
Download the Support Files
You will need to download the necessary support files (634 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.
We will often ask you to load something from
$HIP/LOPS_DEMO_FILES. 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
$HOME/projects/LOPS/LOPS_DEMO_FILES. Then when you load a Houdini file from
$HOME/projects/LOPS, you can refer to the place where the tutorial files are stored as
A Few Things to Know
These tutorials assume at least a beginner’s understanding of Houdini. (How to create objects, how to use SOPs, understand and navigate the interface and different levels.)
It is assumed you are familiar with the basic concepts of USD and LOPs:
Houdini Apprentice license holders will only be able to write out
.usdnc files. This is the non-commercial version of USD, and can only be read by Houdini, (not other packages that support USD). In all other ways it is fully functional.
These are the tutorials that will walk us through a typical pipeline and how we might use LOPS/USD to do this.
Congratulations! You have built your first USD asset and are ready to move on to the next tutorial!
Continuing from the previous tutorial, we will assemble some assets into a bigger asset. This is a miniature version of one of the early stages of a production pipeline, asset creation.
We will layout some assets in a scene, acting at the "sequence" level. This is a miniature version of one of the stages of a production pipeline, layout.
Using the previously-created sequence layout, we will layout some assets in a scene, acting at the "shot" level. This is a miniature version of one of the stages of a production pipeline, layout.
Using one of the previously-created shot layouts, we will create some FX elements which will replace some static elements. This is a miniature version of one of the stages of a production pipeline, FX.
At the end of our pipeline, we are going to be lighting the accumulated contributions of all of the upstream departments. This is a miniature version of one of the stages of a production pipeline, Lighting.