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/ 21.11.2018

Building Better Workflows With Houdini

The Challenge

Moncler is a global luxury brand, known for combining style with constant technological innovation. On February 20th, 2018, Moncler presented the Moncler Genius project, featuring eight distinct collections from eight world-renowned designers. Our challenge was to create an engaging AR experience to highlight both the unique vision of the project and the individual designers.

Meeting the visual demands of a progressive brand like Moncler is a challenge in its own right. This task was made even greater by the need to deliver that vision on a mobile platform in a realtime AR environment.

To succeed, it was clear we required a modular, procedural workflow. Rapid iteration based on feedback was critical to the success of the application. We knew the content was going to be FX heavy. On top of this, the re-use of elements across other parts of the collection was of utmost importance in order to meet a demanding schedule.

From the beginning, it was clear that Houdini offered REWIND the best solution. Houdini is, of course, well known for its industry-leading VFX tools, as well as its capabilities in helping create procedural geometry. These two things provided a compelling argument to use Houdini, but it is also worth mentioning its value when it comes to the rapid creation of smaller, secondary assets, thanks to SideFX’s continuing work on its Game Development toolset.


Making Ice & Rippling Liquid

A common theme throughout much of the Moncler Genius collection was the use of ice. The front cover of the collection comprised of the Genius building logo growing from nothing into a fully formed ice sculpture. The creative challenge for its motion was: ‘thawing in reverse’. We were faced with a number of creative approaches to achieve this. Did we want to melt the ice and then reverse that process? Did we want it to appear to dissolve like wax? Or did the effect need to grow organically like real ice? In other packages, each of these options would have been time intensive and a technological challenge all of their own. To ensure the client was happy with the chosen direction, rapid prototyping was essential.

A real benefit of using Houdini to create these complex effects is that large parts of the prototyping process can be carried forward to the final production. For example, nodes that could turn target meshes into Signed Distance Fields (SDF’s) could then be reused to make sure the result matched the target geometry exactly. Tools produced in-house using spatial colonisation algorithms were repurposed to create the animation of ice growing.

We also used Houdini to help accelerate simpler tasks. The collection titled ‘Noir’ employed a rippling liquid surface effect that was achieved by panning a normal map of ripples upwards in UV space. The trick to the technique was to create a disk of geometry where the top of the UVs lay at the outer edge, and the base of the UVs were positioned at the centre. Creating such geometry, while simple, can be laborious in a non-procedural environment.


The Challenge Of Mist

Another challenge was to create mist that realistically rolled down the sides of a mountain. The perfect solution involved the use of flowmaps, which can be notoriously difficult to author. Houdini made it relatively simple to derive the direction of flow from the tip of each mountain peak to the base. We could then encode this as a motion vector inside UV space after a simple bake it was ready to be used in-engine. Houdini made it possible to swap out the input mesh of the mountain and re-simulate the flowmap. This happened numerous times during the project as the mountain shape constantly evolved. Houdini ensured the effects could adapt to these changes, without them eating significantly into development time.  


Did somebody say Voronoi?


No VFX project would be complete without a little destruction. Houdini gave us the ability to create a Voronoi fracture to simulate a sinkhole from below the concrete surface. The end result was then baked into an animation that could be used simply and performantly inside Unity.  

The creative required that vegetation grew from out of the resulting sinkhole. To achieve this, points were scattered from inside the hole which then spawned instanced plant geometry from each point. To achieve the plant growing effect, the origin of each plant instance was then placed into the UV channel. A normalised growth map was added to the colour channels to give the effect of each plant growing from its root. A more natural looking effect was achieved by offsetting each plant’s growth using the Houdini generated growth map. As the last stage, the whole effect was then driven by a custom shader from inside Unity.

Without Houdini, we would have lost a significant amount of time to development and wasted work, rather than polish. Houdini allowed us to focus more on creating and less on worrying about whether the approach would lead us to a dead-end. Knowing that you have the flexibility to change things late in the project’s lifecycle is a great comfort.  

Houdini is typically associated with big budget games and film, it’s not software usually associated with AR content creation, or indeed, the fashion industry. Hopefully, this article helps to illustrate the potential wider application of this toolkit and to inspire others to start using the software.


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