The Art of Crafting Full 3D Scenes with Houdini
Join Sehee Kim, an aspiring FX Artist and Inha University student, as she ventures into the world of simulation in Houdini.
Sehee Kim is a graduate of Inha University, and a Junior FX artist based in Korea. For her latest demo reel Sehee explores the world of simulation in Houdini for her latest project. Focusing on dynamic elements such as pyro, smoke, particles, and ocean simulations, she shares how she crafted a scene comprising five distinct layers, each contributing to the breathtaking visual experience she seeks to create. This article offers valuable insights and inspiration for aspiring FX artists...read on!
With the exception of the ship, soldier 3D asset, and sky HDRI, all the elements in the scene were created using Houdini. This was a challenging task, but I am proud to have completed it and feel satisfied with the results.
I am also excited and honoured to write a blog post for The Rookies, featuring this project. I hope that sharing my work will be helpful to aspiring Houdini artists who want to learn from the projects I have worked on.
Software Used
Reference
To create a large-scale scene, I drew inspiration from a war movie, specifically "Midway". I wanted to replicate a scene where a ship catches fire and is subsequently extinguished. This scene intrigued me due to the massive explosion and the potential to create realistic sea and water effects to simulate extinguishing the fire.
I started by looking for other live-action video references to work on this scene.
Maintaining a clean and organised approach is crucial when searching for references in the process of creating a photo-realistic simulation.
The goal is to achieve a high level of realism, and looking for actual reality images for reference is essential. Through this process, one can identify details that may have been overlooked otherwise.
For instance, let's consider the scenario of creating an explosion. The size of the explosion, the amount of smoke generated, and the duration of the fire can vary depending on the scale of the explosion. Accurate simulation of these elements can only be achieved by thoroughly examining images of actual explosions.
By diligently researching and observing references, we can ensure that our simulations are based on real-world observations, resulting in a more realistic and convincing visual effects outcome.
It's a critical step in the production process that should not be overlooked, and it plays a significant role in achieving a high level of authenticity in the final result.
Simulation
Making a water cannon
Houdini's water cannon illusion has always been associated with water, but upon reviewing the references, a new idea emerged. The illusion involves a massive amount of water gushing out all at once, creating the appearance of smoke flowing from a waterfall. This led me to consider whether the illusion could be better portrayed as a vast mass of steam rather than water. Additionally, since the water cannon was designed to be seen from a distance, I believed that focusing on the overall shape and sense of mass was more important than meticulously depicting the details of water.
To achieve this in the simulation work, I decided to use a pop solver instead of a heavy flip solver. The pop solver provided a lighter and more efficient solution for the task. Furthermore, I felt that working with particle simulation would be ideal for conveying the effect of pouring water vapour, even though it technically represented water. By utilising particle simulation techniques, I aimed to capture the essence of the illusion more effectively.
In order to enhance the water-like effect, I applied motion blur after the particle simulation. This technique lengthened the particles and maximised the illusion of water, adding to its realism. The combination of particle simulation and motion blur allowed for a more convincing representation of the water cannon.
As a result of these approaches, it became possible to reproduce the water cannon illusion with a lighter computational capacity. By prioritising the overall shape, mass, and visual impact, the illusion was successfully recreated, breathing new life into Houdini's remarkable performance.
Create a Lasting Explosion
During my exploration of simulation techniques in Houdini, I encountered a fascinating reference where the smoke appeared unaffected by burning, while the fire continued its blazing existence. Replicating this intriguing phenomenon proved to be a challenge, as achieving the desired shape in a single simulation run seemed elusive. Consequently, I devised a strategy to overcome this obstacle by dividing the simulation layer into two parts. By capturing the distinct shapes separately and subsequently combining them, I successfully recreated the reference shape.
Additionally, while working on simulating explosions, I discovered the significance of the emitter's shape in achieving realistic results. While numerical adjustments play a crucial role, I noticed that the shape of the emitter had a discernible impact on the simulation outcome. To address this, I diversified the emitter shapes, incorporating elements such as noise, grouping, and spreading out. By skilfully blending areas with intense fire and those with more subtle flames, I created intricate shapes that accurately reflected the dynamics of the reference.
Through these endeavours, I not only achieved the desired shape and captured the essence of the unburnt smoke and continuing fire, but I also gained a deeper understanding of the role of layer division and timing adjustments using timeshift. Moreover, I experienced firsthand the significant influence of emitter shape on simulation outcomes, emphasising the importance of thoughtful manipulation to produce visually compelling results.
In conclusion, my exploration of Houdini's simulation capabilities led me to replicate a captivating reference where smoke remained unaffected by burning while the fire persisted. By dividing the simulation layer, adjusting burning timing, and employing diverse emitter shapes, I successfully recreated the desired shapes and faithfully represented the mesmerising interplay of smoke and fire. This endeavour exemplified the versatility of Houdini as a tool for visual effects and highlighted the artistic considerations necessary to achieve realistic and captivating simulations.
Volume source
I utilised volumetric effects to simulate environmental smoke. To prevent the smoke from becoming overwhelming and obstructing the entire screen, I confined it to the space within a designated box. By employing the camera spectrum, I effectively removed the smoke from invisible areas outside of the box.
To create the jagged appearance of the smoke, I utilised a vop node. This node allowed me to connect the position and time parameters and introduce noise using turbnoise. As a result, the volume of the smoke appeared jagged and fragmented, adding a sense of drama and intensity as the smoke moved around the explosion.
Overall, these techniques helped to create a visually engaging representation of environmental smoke in the article, drawing attention to the impact and dynamics of the situation.
Ocean layer texture
When simulating the sea in the Houdini, I focused on setting the speed and height of the waves as points. However, the process of adding texture to the sea was crucial in achieving a realistic and visually appealing result. By following a tutorial on integrating nodes into the ocean shader, I aimed to replicate colours found in real-life seascapes, aiming for realism. I discovered that the colour and height of the waves significantly influenced the perception of the sea.
Through adjustments, I was able to simulate various environments such as the deep sea, transparent waters, and shallow coastlines, each with its unique atmosphere. The experimentation with different colours and heights brought a sense of enjoyment and creativity to the process.
Ultimately, the combination of wave parameters and texture added depth and realism to the simulated sea in Houdini.
Importance of lighting in Houdini
While simulation is crucial in Houdini, proper lighting is equally indispensable when creating compelling visuals. The way a simulation appears can be significantly influenced by lighting. Therefore, in the process of creating an image, addressing lighting becomes a vital task for Houdini users.
In order to achieve the desired lighting effects, I implemented several lighting techniques. This included using an environment light, a sun light, and a key light to illuminate the environment, aiming to replicate the lighting conditions from a reference image.
I also provided an example that showcased the impact of different light positions on the simulation's appearance.
By carefully positioning the light sources relative to the simulated elements, I discovered that the shape of the fire varied and the focus of attention shifted. This highlighted the significance of lighting in emphasising specific elements and enhancing the overall visual composition. Notably, the lighting adjustments acted as the final step in the process before rendering, following the simulation phase in Houdini.
In conclusion, while simulation is crucial, the proper implementation of lighting is equally important in Houdini. It has the power to transform the appearance and impact of a simulation, making it a vital consideration in the overall creation process.
Understanding the program
In Houdini, knowing how to handle the program is important, but equally crucial is the ability to approach problem-solving in diverse ways. The expression and resolution of objects can vary depending on factors such as shot size and camera angle. Houdini offers infinite creative possibilities, allowing users to find their own unique approaches. Although it may be challenging, particularly with VEX scripting, the program's complexity adds to its appeal.
The simulation in Houdini is highly sensitive to various parameters, making it an attractive and challenging tool. I acknowledges the difficulty but expresses determination to become a skilled Houdini artist through continuous effort.
Reach out to Seehee via her Rookies portfolio here and LinkedIn.