Grass Interaction

Result of R&D and Chosen Workflow

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Grass interaction is an issue that we had minimal time to research during the Preproduction as the group prioritized the most important issues we faced. Ethan Pflugh and I were looking into the issue of grass with two different software packages, qualoth in Maya and Houdini hair/fur systems. To save on time, Ethan researched and experimented with qualoth while I looked into the Houdini side of things. Qualoth has a proven workflow but appeared slow and was a plugin for Maya, which means crashing could be a frequent issue. Houdini’s hair and fur systems are extremely powerful, look great, and crash far less often when compared to Maya. Although the hair systems were extremely powerful in Houdini and could do everything the group needed, qualoth can also be used to work with plant and bush interaction as well. Ethan and I decided on the qualoth workflow over the hair and fur systems in Houdini for the ability to mix plant interaction with grass without having to combine multiple systems to achieve a desired look. Since we decided on using qualoth, Ethan will most likely be taking over the interaction for production.

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What Makes the Hair and Fur Systems in Houdini So Powerful?

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Hair and fur systems were designed to give the user full control of the simulation and design. All hair and fur are driven by curves which can be sculpted to fit differing styles, can be guided by points of the surface connected to the system. The method of calculation in Houdini has been iterated upon and is faster than we had seen in Maya. Having more efficient means of calculation allows more work to be done in less time. Now that qualoth may have some of these features as well, it is slower to process the actions of the user leading to increased wait times between actions. Not being driven by a plugin offers much more control if we were to reach outside of interaction. If more complex simulations were added in, Houdini overall is the perfect software to use. If fire, water, or complex rigid bodies simulations were needed in areas where interaction occurs, we would most definitely have gone with Houdini’s offerings.

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What’s Left for Grass and Plant Interaction?

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Scene layouts are nearing completion and vegetation will be hand placed to have complete control of the close-up areas of the forest where interaction may occur. Some of the group is working on getting animation together using the mocap suit, which should allow work on vegetation interaction to resume fairly shortly.