Having worked with Digital Assets and building tools for a few years now, I have a clearer picture of how to approach their design. I have come up with three different approaches that take into account pipelines built using both Houdini Master and Houdini Escape. At first glance Houdini Escape does not allow you to work with particles and dynamics but in reality it has some unique abilities that impact us as production tool designers.
Houdini Escape and the Bigger Tool Design Picture
Houdini Escape is a version of Houdini that lets you create and work with all of Houdini's network levels except for Dynamics (DOP) and Particle (POP) networks. But if you open a scene built in Houdini Master in Houdini Escape you can cook these networks and run simulations. This way you can use Houdini Escape to animate and light your shots even if they incorporate visual effects. If you build Digital Assets that encapsulate POP and DOP networks, you can promote parameters to the top level of the asset to get even greater artistic control.
When we design tools, we either design them to work inside Houdini Escape or not. I bet that most of you have not. Apprentice users use Houdini Master. Many shops use Houdini strictly for VFX work and may have not considered Houdini Escape in their pipeline.
So how does Houdini Escape allow you to play back a sim but not be able to edit it? The answer lies in the unique architecture of Houdini. Internally Houdini shares many similarities with a file system in that there are directories and files that represent the various network types and the nodes inside those networks. We simply don't give you permission to edit particular nodes or networks directly. We do allow those networks to function as they would in Houdini Master. No changes whatsoever in the playback or renders with Houdini Escape. And parameters that channel reference parameters at the top level of a Digital Asset can be modified and even keyframed to help control the asset.
This ability of Houdini Escape to open up any Houdini Master file with no loss of functionality is important for many reasons. You can choose to work with fewer Houdini Master seats to build your tools then pass them on to a larger team of Houdini Escape users for layout and animation. This will save you money when you set up your Houdini pipeline although it does require some forethought from your tool designers.
How does this impact your design of Digital Asset tools if you want to use them with Houdini Escape? Basically, your tools have to be compatible with the networks that can be edited in Houdini Escape. Mainly OBJ's, SOPs and COPs but the other accessible networks are certainly valid as well.
In the video, I show a Contrail tool that uses a POP network controlled by high-level parameters. It is an object-based tool so the Houdini Escape user can freely add this tool at the object level and in effect, have a pop network in their scene without using Houdini Master.
Different Usage Models for Tools
Now that you understand the role Houdini Escape can play, it's time for me to introduce the three tool design models that are discussed in the video. Each method takes into account who the tool is designed for and whether it is being used in Houdini Master or Houdini Escape:
Single Usage tools allow you to complete a task in a single step. They can be used by novice Houdini users to get advanced results with little intervention. They are designed to work in Houdini Escape.
The ConTrail Tool in the video falls into this category. It can both supply it's own source geometry and emit particles. It has a simple interface. It is added at the object level.
Multiple Usage tools require multiple steps to complete a task. They are designed for all Houdini users including beginners with a bit of an understanding of Houdini. They are designed to work in Houdini Escape.
The ConTrail Tool, although self-contained, can also be used as a multiple usage tool with many external dependencies to a variety of particle source geometry in other objects. It is designed to work well with one or two other tools to compelte the task, all in Houdini Escape.
Discrete Micro Tool UsageMicro Tools are the bits and pieces that comprise the single and multiple usage tools. They require a good understanding of Houdini to use. This places these tools in the hands of intermediate to advanced users. They are designed with no restrictions. Houdini Escape restrictions do apply and ultimately these are designed to be used by Houdini Master TD's. They can also be nodes that perform tasks in areas beyond Houdini Escape.
Modular Approach to Tool Design
So now to the main point. I am proposing a design method of building and implementing tools in a way that is scalable in many ways. The tools increase in complexity as the user works with the tools. The tools progress gracefully from Houdini Master to Houdini Escape and back again if necessary allowing facilities to manage costs with no impact on quality. It gives you the ability to match skills with tools without introducing artificial barriers for the end user.
Many of us are already building Digital Assets that contain smaller Digital Assets. The idea here is to think the entire process of designing a bunch of tools that complete tasks from top to bottom.