From Earth: Abstract Liquid Vase Simulation in Houdini

Workflow

Houdini is amazing for defining the core elements of a project and then allowing you to elaborate and blend them together in the future.  If you are able to clearly describe a scene or visual, then you can create in Houdini. The way in which you describe the scene just depends on what you are trying to accomplish and that can vary depending on the project or artist.

I broke this project down in a way that made sense with the course materials. It began during a lesson on point clouds, so I actually started with the fluid simulation as I was already working on that. 

Once I got comfortable directing the particle motion, I moved on to the vase animation and finally the grain simulation. I broke the project up based on the individual simulations and converted them into collision volumes when I needed them to interact with each other.

Simulation Breakdown

The entire project was a series of simulations interacting with each other. The basic vase geometry was created with basic hard-surface modeling techniques. I used the curve, revolve, and polyextrude tools in this case.

For the swirling fluid effect, I drew the exact path I wanted the particles to travel using the curve tool.  The particles were emitted and pushed along the curve by setting their velocity relative to the tangent of the curve in a particle VOP. Building off of the class lesson on point clouds, I set up a number of parameters in a particle VOP such as noise, offset, and attraction force to the curve.  As the particles get closer to the small neck of the vase, their attraction to the curve increases gradually so they can enter smoothly.  

The grains were the most challenging part of the project for me. They required a lot of trial and error to get right and there weren’t many shortcuts for notably faster results. I found that increasing the simulation substeps and collision volume density was needed for good results.  I isolated the simulation to as small of an area as possible and then instanced large patches of sand grains around it to fill in the void around the main sim.

The large details of the vase were taken care of by initial particle simulation converted to a volume. I added noise to the y-axis of the volume to make sure the edges felt uneven and organic. Using a VDB Combine node, I used the original vase model as a mask for the blobby particle simulation. This created the basic vase animation which I repeated and layered several times to get the final result.

I then introduced some angular and rigid properties to the glass portion and outer structure of the vase.  This look was based on images of faceted clay pottery. This look has a hand-made feel that I felt added a bit of lore and mystery to the final piece.  The faceting was created by using a Voronoi noise formula to displace the geometry along its normals.

I then created an attribute ramp along the y-axis of the vase to limit the displaced areas of the geometry.

Rendering

I chose Octane as my render engine for this because I like the way it handles light refractions and I also had experience using instancing with Octane so I knew it would handle the grains well.  I used different colored key lights to add some subtle variance in the sand grains and vase reflections. 

The main tip I’d give to anybody handling a multi-part project like this is to test your render times regularly throughout the process. When working with grains, be sure to account for the amount of time it takes for your GPUs to load all of the instances into VRAM.  When you are just rendering single frames, it can be easy to overlook basic things like network and GPU bandwidth.

Working on Abstract Art

A lot of my work begins by deciding on what emotion I want to convey to the viewer. How I go about telling a story is mostly influenced by my personal life experiences. My background growing up at the beach influences a lot of the artistic decisions I make. 

Since becoming more comfortable with Houdini, most of my experimenting is now done by doodling in a notebook. I never have to worry about if I’ll be able to make something with Houdini so I spend a lot more time focusing on the core concept. 

For anybody who is getting started with abstraction, I would just recommend to cherish their own personal life experiences and use them to inspire their creativity.  Your environment, relationships, hobbies, and interests all provide a wealth of details to pull from. 

Time Management

From Earth was a project with a lot of moving parts in a short period of time. I had to work as efficiently as possible so I was forced to define a clear creative vision and plan of action ahead of time. My time was split between ‘learning’ and ‘making’ and the weekly deadlines kept me from getting hung up with the learning portion.

When working on personal art projects like this, it’s important to remember that it will never really be finished. You will always be able to experiment and tweak endlessly, usually until you can’t stand the project anymore. Give yourself deadlines and creative constraints so you don’t wander too far from your original vision.

Conclusion

Abstract art can be overwhelming when we’re constantly surrounded by amazing work from talented artists. It can sometimes be easy to over-indulge in learning new tools or enjoying other people’s art.  We are all learning from the same pool of resources, so the most important elements of your art are those that stem from your own life experiences. Every idea has value so pick one that is personal and bring it to life.

James Tupper, Designer & Filmmaker

Interview conducted by Daria Loginova