In the early special effects film “The Ten Commandments”, directed by Cecil B. DeMille in 1956, the filmmaker showed ‘The parting of the Red Sea scene’. This scene is considered one of the most iconic and memorable scenes in the history of cinema. The scene depicts the moment when Moses, played by Charlton Heston, leads the Israelites across the Red Sea, which parts to allow them to escape from the pursuing Egyptian army. The special effects used to create this scene were ground breaking for the time and have been widely studied and admired for their technical achievement. The scene was created using a large water tank. The water from the large tack was flew and the footage of the water being parted and the Israelites crossing was filmed in reverse, with the water appearing to come together rather than parting. 

The filmmakers also used detailed matte paintings and miniatures to create the illusion of a vast and deep sea. The matte paintings were used to create the illusion of depth and distance, while the miniatures were used to create the illusion of a large scale event.

Traditionally, the film industry has used a combination of practical effects and visual effects to simulate the movement of liquids in films. Practical effects involve the use of real liquids on set, often filmed in slow motion to create a more realistic and fluid movement. Visual effects, on the other hand, involve the use of computer-generated imagery (CGI) to create the movement of liquids in post-production.

In traditional films, practical effects were heavily relied upon to create liquid movement. This often involved the use of large water tanks and miniature models, as well as the use of high-speed cameras to film the movement of liquids in slow motion. This approach was often time-consuming and expensive, but it allowed for a level of realism that was difficult to achieve with CGI alone.

In recent films, the use of CGI has become more prevalent in creating liquid movement. CGI allows for a greater degree of control and flexibility in creating the movement of liquids, and it can be used to create a wide range of liquid behaviors and effects that would be difficult or impossible to achieve with practical effects alone. Additionally, recent advancements in computer technology have made it possible to create highly realistic and detailed simulations of liquids that are difficult to distinguish from the real thing.

In this introduction, we will explore the techniques used to create realistic liquid in film and discuss how to avoid the uncanny effect. We will also look at some examples of films that have used these techniques to create believable and immersive liquid simulations, such as The water tentacle scene in the film "The Abyss" by James Cameron and I will create a liquid simulation with using Bifros in Autodesk Maya software.  
 

The concept of the "uncanny" has long been of interest to scholars and researchers in a variety of fields, including psychology, literature, and computer science. The term "uncanny," which is derived from the German word "unheimlich," refers to something that is strange or unsettling in a way that is difficult to define or explain. In the context of virtual effects, the uncanny is often used to describe simulations that are eerily artificial or that fail to convincingly replicate the appearance and behaviour of real-world phenomena.

One classic definition of the uncanny was provided by Sigmund Freud in his 1919 essay "The Uncanny." Freud argued that the uncanny is characterised by a feeling of familiarity that is mixed with feelings of discomfort or revulsion. He suggested that this feeling is often triggered by experiences or objects that are related to death or the return of the repressed, and that it is closely tied to our primal fears and anxieties.

In the field of computer graphics, the uncanny valley is a term that is often used to describe the phenomenon of a simulation becoming increasingly realistic up to a point, at which it becomes unrealistic and unsettling. This term was coined by Japanese roboticist Masahiro Mori in 1970, and it has been widely discussed and debated in the decades since. Many researchers have attempted to identify the factors that contribute to the uncanny valley effect, and to develop strategies for avoiding it when creating virtual effects. 

One key factor that has been identified as contributing to the uncanny valley effect is the level of realism of the simulation. As a simulation becomes increasingly realistic, it can become increasingly unsettling if it falls short of achieving complete realism. This may be due in part to the fact that our brains are highly attuned to detecting subtle discrepancies and inconsistencies, and we are especially sensitive to deviations from what we expect to see in the natural world. Another factor that has been identified as contributing to the uncanny valley effect is the level of anthropomorphism of the simulation. When a simulation is designed to be humanlike or to replicate human behaviour, it can be particularly unsettling if it falls short of achieving a fully humanlike appearance or behaviour. This may be due in part to the fact that we have a strong tendency to attribute humanlike qualities and intentions to non-human objects and entities, and we are particularly sensitive to deviations from this expectation. 

The concept of the uncanny is closely tied to our primal fears and anxieties, and it is often triggered by experiences or objects that are related to death or the return of the repressed. In the context of virtual effects, the uncanny is often used to describe simulations that are eerily artificial or that fail to convincingly replicate the appearance and behaviour of real-world phenomena. The uncanny valley effect is a phenomenon that has been widely discussed in the field of computer graphics, and many researchers have attempted to identify the factors that contribute to it and to develop strategies for avoiding it when creating virtual effects.
 
In recent years, there has been a growing recognition of the importance of creating realistic and believable simulations of natural phenomena, particularly in the fields of computer graphics and virtual reality. Simulations of fur and liquid, in particular, present a unique set of challenges due to their complex and dynamic nature.

 A number of researchers have addressed the issue of simulating fur, exploring various techniques for modelling the overall shape and movement of the fur, as well as the way it reacts to light and other stimuli. One such technique is the use of physically-based simulation, which seeks to model the behaviour of fur based on physical principles such as forces and torques. This approach has been shown to be effective in producing realistic and believable fur simulations, although it can be computationally intensive. 

Other researchers have focused on more data-driven approaches, using machine learning techniques to model the behaviour of fur based on examples from real-world data. This approach has the advantage of being able to capture a wide range of behaviours and can be more efficient than physically-based simulation, but it may be less physically accurate. Simulating liquid, on the other hand, requires a different set of techniques due to its fluid nature. One common approach is the use of particle-based simulation, which models the liquid as a collection of individual particles that interact with each other and their environment. This approach has been shown to be effective in producing realistic and believable simulations of liquid, but it can also be computationally intensive.

 Another approach is the use of grid-based simulation, which divides the liquid into a regular grid and solves the equations of motion for each grid cell. This approach can be more efficient than particle-based simulation, but it may be less accurate in capturing the behaviour of the liquid. Regardless of the specific approach used, it is clear that simulating natural phenomena such as fur and liquid is a complex and challenging task. However, the importance of creating realistic and believable simulations cannot be overstated, as they can be used in a wide range of applications, from movies and video games to virtual reality experiences. As such, there is a growing body of research dedicated to improving the realism and believability of these simulations, with the goal of creating virtual effects that are as close to the real thing as possible.

The uncanny effect, also known as the "uncanny valley," is a phenomenon that occurs when an artificial or simulated object or effect is almost like realistic. In relation to simulating liquid in film, the uncanny effect can occur when the simulated liquid does not look or behave like real liquid. This can happen for a variety of reasons, such as incorrect lighting, inaccurate movement, or unrealistic properties. For example, if the simulated liquid does not reflect light in the same way as real liquid, it can appear flat and unrealistic, breaking the illusion and pulling the audience out of the story.
 
The uncanny effect is particularly relevant in simulating liquid in film, as liquids are often used as a background element or to create a specific mood or atmosphere. If the simulated liquid is not realistic, it can detract from the overall visual appeal of the film and weaken the audience's immersion in the story.
 
To avoid the uncanny effect when simulating liquid in film, filmmakers and special effects teams must pay close attention to detail and carefully study the properties of liquids. This includes researching the way liquid moves, how it reflects light, and how it behaves under different conditions, such as in a storm or underwater. Additionally, filmmakers can use a combination of practical and computer-generated effects to create more realistic liquid simulations. Practical effects such as filming real liquid in slow motion, and using live action footage to simulate the movement of water and use of computer-generated imagery to create the underwater world and other visual effects such as bubbles, distortion and so on.