Visual Effects 2: Houdini Fluids

Here is the flipbook and render of my Houdini Fluids assignment for Visual Effects 2. For this assignment, we were allowed to do whatever simulation we wanted, as long as it was something we had not done before. Because I still don't know much about Houdini, I decided to stick with that program, trying out the Fluids side instead of the Pyro. I chose to running water from a sink because I knew that Fluids have to have millions of particles in order for the water to look correct. This way, I could still try water but keep my computer from blowing up. I was surprised at how fast water actually runs out of a faucets. I suppose that I had just never really paid too much attention before. Still, I think that my simulation may run slightly fast. Other then that, I am fairly happy with out it turned out.

Below, you can see the plan that I wrote up before starting the simulation.

           For this assignment, I will be simulating water running from a sink faucet. To start off, I will model a simple sink in Maya. The sink will include the bowl, the faucet itself, handles, and a raised stopper. Once this is done, I will import these assets into Houdini as one mesh. I know that I want the fluids to hit the sink and bounce off, just like they would in the real world, so I will select the sink mesh and turn it into a Static Object under the Rigid Bodies tab

            To start the fluid simulation, I will create a sphere to emit from, and then under the Particle Fluids tab, select Emit Particles to create the fluid Flip Tank. This sphere will be placed under the faucet opening.  To adjust the flip tank size and shape, I will go into the flipsolver and change the Box Shape numbers. To change the position, I will adjust the Box Center I will size this to fit only the area that I need – from the faucet to the base of the sink. Next, I will go inside the AutoDop Network in order to adjust the motion. Before adjusting any motion, though, I must first change the Visualization of the fluid to Particles inside the flipfluidobject. Once that is done, I will lower the Particle Separation to create a more detailed and interesting splash. If I find that the splash is not going quite as fast as I want, then I will raise the gravity of the fluid.

            Once I have the motion looking nice, I will then move onto the shading of the water. The first thing that I must do is set up a light. If a light is not projected onto the fluid, then I will have a hard time adjusting the settings for an accurate portrayal of water. To do this, I will create a simple Directional Light and aim it towards the sink. Once this is done, I will adjust the shader by turning the Cloud Density to 0 in the uniformvolume node. This is because the fluid I am making is transparent water, not a type of smoke. After that, I will move onto the color. Inside the basic liquid node, under the Diffuse tab, I will adjust the Base Color to be a slightly less overpowering blue. Also, I will make sure that the Color in the Reflection tab is lighter than the Base Color. Once that is done, I will make sure that the Index of Refraction under Settings is set to that of water – 1.33.

            After I have all of the motion working correctly and the shading matches that of water, then I can render out my sequence and create a Flipbook of my simulation.

Here is the simple sink prop that I modeled for the scene.

Visual Effects 2: Houdini Pyro

Above is the flipbook and render of my Houdini Pyro assignment. For our next project in Visual Effects 2, we had to use the Pyro option in Houdini to create fire. I chose to create a torch, for this one. I had much more trouble with this assignment than the first one. Overall, I just have a harder time understanding Houdini, but I did try my best. I could use a lot of work, though. The fire itself is too large to be a real torch. Also, it fluctuates too much. Still, the color is fairly nice

Here is the plan that I typed out before starting.

           For this assignment, I will be making a torch fire. To start off, I will model a very simple torch in order to have a prop in the scene to add to the effects of the fluid. Once the models are placed and scaled correctly in Houdini, I will then start the fluids by creating a torus to emit the Smokeless Flames. Setting up the container is the next step. This must be done before adjusting the motion of the fluid. I will adjust the Division Size so that the container has more resolution. I will also make sure that the voxels remain square in order to not cause distortion. For even more control over the motion, or if I wanted to view a certain part individually, I can go into the Pyro node attributes for the container. 

            Next, I will adjust the motion of the fluid so that the flame looks more believable. I will do this in they Pyro Solver of the AutoDopNetwork.  Under the Simulation tab, I will start by adjusting the Timescale in order for the fire to move faster. However, because of this, I will need to also adjust the substeps of the fluid in order to not lose detail. I will also make the flames shaper, or more crisp, by lowering the Temperature Diffusion. The Cooling Rate will be raised in order to keep the flames small and contained.

            Continuing on with the movement, I will go into the Combustion tab and slightly adjust the Gas Release to cause a small burst for the initial ignite. I may also look at adjust the Ignition Temperature, to make sure that the flame starts burning on frame 1, and Flame Height, in case the fluids need to be taller.  To finish up the motion, I will go into the Shape tab and adjust the Confinement. This will create the swirling effect of the flames that we see in torch fires.

            Once the motion is all done, I will move onto the shading. Going into the Shop network, I will start by adjusting the color in the Color tab. I will switch Constant to Artistic, so that I can create the strong color variation of fire. If needed, this is where I would do any type of color correction before rendering. After the material has been finished, the only thing left to do is to complete a memory cache of the simulation and render. I will do this by creating a camera for the render view and then creating a Mantra-PBR node. From here, I will set up my render options and render out an image sequence. This sequence will be taken into either After Effects or Nuke and be exported as a movie file.

Visual Effect 2: Maya Fluids

Here is the playblast and render of my assignment for my Maya Fluids project. For this, we simply had to make a fluid container in Maya and adjust the attributes to fit our reference. We were required to do some sort of fire, so I chose to do a fireplace. Overall, I am fairly happy with the result. It could definitely be a lot better, though.

Here is the plan that I wrote out before starting. As always, it's best to have a plan before doing anything.

          For this assignment, I plan on making a fluid fireplace scene. To start off, I want to model simple props for the scene. These will include a fireplace mantle, a grate, and a large log for the fluid to be emitted from. These models will be simple and quick because more time should be spent on learning the dynamics of fluids then modeling. Once all of the assets are placed in the scene, I will create a fluid container to fit the size of the fireplace cut out by changing the size and resolution in the Container Properties tab. This way I can make sure that the fluids are contained to the specific area of where a real fire would take place. Also, having the fluid container match the direct size of the fire will cut down on simulation time.

From here, I plan to turn the log model into a fluid emitter. Once the log is emitting fluids, I will start by adjusting the density. The fire needs to stay someone transparent, but if it is too transparent then it will appear as smoke. Raising the density should fix this. I will not adjust the heat very much, if any, because I don’t want the fire to rise very much. The same will be said for fuel. Because this is not an explosion, I do not want to add fuel to the fluid dynamics.

Next, I will go into the fluidShape tab and adjust the motion and shape. Here, I will adjust the Boundary in order for the simulation to not cap off at the sides. I will also pay attention to the Dynamic Simulation. I will adjust the Simulation Rate Scale, in order for the simulation to play faster. This will help to speed up the flames. Continuing on with the finer details of the motion, I will move to the Content Details. Under this tab I will raise the Dissipation to shorten the lifespan, slightly adjust the Diffusion, and raise the Density Tension so that parts of the flame can flicker and break off. I will also try the Swirl option under velocity. Still, this is an option that will only be slightly adjusted, because the fire, for the most part, will stay stationary. Ultimately, this section will take a lot of tweaking for me to find a shape and motion that best matches the reference. Most of my time will be spent on this section.

Once the motion follows the reference as closely as possible, then I will move into the shading of the fire. Under the Shading tab, I will change the Color to black and adjust the Incandescence color ramp, because fire is self-illuminating. I will also make sure that I add a small amount of Glow to the shading. Because fireplace flames are thinner at the bottom than at the top, I will adjust the Opacity ramp in order to match the reference. Once I am finished adjusting the shading attributes, and I notice any pixilation issues, then I will slightly raise the Shading Quality. After all of the fluid dynamics are finished, the only thing left to do is to add an illuminating point light, texture the props in the scene with a lambert, and then finally render.

Visual Effects 1: Lesson 3

 

On the right is a playblast of my third assignment while on the left is a render. For this projects, were were focused on learning soft bodies. I was pretty apprehensive with this so I just stuck with the default scene. I didn't want to get ahead of myself. But, as I worked on the assignment, I found the overall project to be fairly simply. Yes, is was the scene provided, so all of the goals were set up for the soft bodies, but actually getting the movement to slow and melt the way I wanted it too wasn't as difficult as I was expecting. Overall, I'm pretty happy with how this turned out. I do suppose I could have spent more time adjusting the fluid of the flame, but the main assignment was to focus on the soft body movement. 

Visual Effects by Hannah Epling

Model of man provided

Visual Effects 1 - Lesson 2

    

This is my second assignment for my Visual Effects 1 class. For this lesson, we had to work with particle systems in Maya Dynamics. The left video is a playblast, while the right is a render.

The only part that I really struggled with on this assignment was the smoke. For one, I was having issues just getting the particles to form in the shape of smoke. Also, I was having trouble with texture of the smoke. No matter what I did, the smoke always rendered flat, so I added a fractal noise to the smoke once I composited everything in After Effects. Other then that, I'm fairly happy with it.

Visual Effects by Hannah Epling
Scene provided

Visual Effects 1 - Lesson 1

 

For this assignment, we focused mainly on Rigid Bodies of the Maya Dynamics system. The first video is a playblast of the scene. This is from the actual render camera and follows the motion of the ball. The second video is a failed render. I was having issues rendering this scene out for a while. Not only would it not render all the way, but it rendered from the wrong camera. But at least I had something to turn in.

What are you going to do?

Oh well. Overall this scene wasn't too bad. I had a little bit of trouble getting the balls to move fast enough through the scene, so I had to key gravity in a couple areas. It's pretty noticeable, but I tried to hide it. Also, at the very end of the scene when the ball is launched into the air, I feel that it moves too slow before hitting the rotating bowl. 

Animation, Lighting, and Textures by Hannah Epling

Scene and Models provided

Tinker Bell belongs to Walt Disney Studios