Empowering Artists with Intuitive Crowd Tools: Midgård at Nordisk Film Shortcut

2020

Houdini · CVEX · Python

Crowd tools that let artists set up and control agents in Houdini without working through complex simulation nodes.

My role
Crowd tool development, artist workflows and pipeline automation
Context
In-house tool development
Company / Studio
Nordisk Film Shortcut
Status
Used in production
Examples of production crowd shots using Midgård.

At Nordisk Film Shortcut, adding crowds was a recurring task for film and TV productions. However, at the time, using Houdini’s native crowd tools required an in-depth understanding of low-level nodes, making it inaccessible to many artists. To address this, I developed Midgård, a custom suite of crowd tools designed to simplify the process and enable non-expert users to quickly create complex crowd shots.

I built high-level custom nodes with interfaces for setting up and controlling crowds. Artists worked in Houdini’s geometry context (SOPs), without having to configure the underlying simulation networks in DOPs.

Core Functionality and Features

1. User-Friendly Setup

  • Artists could bring in agents from disk, complete with various animations, and quickly place them using a straightforward interface.

  • I wrote custom CVEX shaders to vary colours and textures across agent clothing. The system applied shading variation at render time, allowing artists to introduce variation across a crowd without setting up each character’s appearance individually.

2. Flexible Placement Tools

  • Agents could be placed by drawing directly on surface geometry or using curve paths for them to follow.

  • Geometry could also be added for agents to avoid, ensuring realistic interactions with the environment.

  • Artists could assign animations like walking, running, or jogging with just a few clicks, or use “states” like “seek” to guide agents to specific locations.

3. Automation and Efficiency

  • Shelf tools written in Python allowed for quick setups, enabling even new users to get started within minutes.

  • A robust pipeline for adding new agents and animations ensured the system could be easily updated for new projects. A simple CSV file stored information about agents and animations, and with the press of a button, they were integrated into the system for immediate use.

Shelf tool setup and agent placement in Houdini.
Agent setup with clothing variations applied at render time using custom CVEX shaders.

The video below shows early tests of the tools. Sorry for the low video quality, but the source is a company wide presentation of the tools, for all of Nordisk Film, that was streamed on Microsoft Teams.

Expanding to New Needs: Birds in the Netflix show Elves

As the tools evolved, I extended their functionality to handle shots involving birds for the Netflix series Elves (Nisser). These ranged from small flocks of 3 birds to scenes featuring 600 birds. Using the same principles of simplicity and flexibility, the bird tools allowed for quick setup and realistic behavior.

Challenges and Innovations

Developing Midgård presented several challenges, particularly in making the tools robust and intuitive for non-experts. Some of the key challenges and solutions include:

  • Enabling Non-Experts: Creating an intuitive interface that abstracted the complexity of Houdini’s native tools required several iterations and extensive testing with users. Feedback from artists was invaluable in refining the workflow and ensuring the tools were accessible and efficient.

  • Flexibility and Robustness: The tools needed to accommodate a wide variety of scenarios, from standard crowd setups to new functionality like birds. Continuous development and adaptability were critical to the system’s success.

Pipeline and Reusability

One of the most significant achievements of Midgård was the flexible pipeline built around the tools:

  • Adding new agents or animations was as simple as updating a CSV file with basic information like file paths, labels, and categories. This automation allowed agents to be easily repurposed and reused across multiple productions.

  • Artists could quickly customize agents by assigning objects like hats, canes, umbrellas, and swords, ensuring that each crowd setup met the specific needs of the show.

This pipeline made the tools not only powerful but also incredibly efficient for large-scale productions.

Empowering Artists

A personal highlight of this project was seeing a colleague, new to Houdini and entirely unfamiliar with crowd systems, create a shot featuring hundreds of autonomous agents in half an hour. This moment underscored the success of the tools in empowering artists to bring their visions to life without requiring deep technical expertise.

Midgård transformed how crowds were handled at Nordisk Film Shortcut, enabling faster, more flexible, and artist-friendly workflows. From large-scale crowd shots to intricate bird flocks, the tools streamlined complex processes and allowed artists to focus on storytelling rather than technical setup.

Building a system that other people could actually use — and use confidently, without needing to understand what was happening under the hood — turned out to be a more interesting design problem than the technical side alone. It's a principle that carries directly into the pipeline and tool development work I do today.