Questneers : Yong-Taek Hong (Seoul National University), Jae-Hyeung Park (Seoul National University)
When will spatial display technology that creates images floating in the air, like scenes in movies, come to us? Can we implement spatial displays that break away from two-dimensional flat displays and create images in three-dimensional space? What are the main technical challenges for implementing spatial displays that can flexibly integrate virtual and reality, and where should the development direction of such technology head?
Over the past decades, display technology has developed in the direction of satisfying humanity’s desire to see the world more clearly and vividly. Modern displays have achieved high resolution and rich color expression through cathode ray tubes (CRT), liquid crystal displays (LCD), and self-emitting displays (OLED), and have become the most essential daily items in modern life by being applied to various electronic products such as televisions, smartphones, and smartwatches. However, displays still express information restrictively within two-dimensional flat screens, and their form has not greatly deviated from the standardized rectangular appearance. In contrast, the movie ‘Minority Report’ features hologram displays that can be controlled with hand gestures, and the movie ‘Iron Man’ features stretchable displays that can be freely expanded and contracted. Such displays that have free form factors without predetermined frameworks and can express information in three-dimensional space are called ‘spatial displays,’ and future displays will develop in the direction of realizing spatial displays.
As often depicted in movies, to express three-dimensional information in empty space, it is necessary to form display pixels in arbitrary three-dimensional space. The minimum unit that can be allocated to different points in three-dimensional space is defined as a voxel, a compound word of volume and pixel, and various methods for implementing voxels have recently been proposed. For example, there are methods of floating small plastic particles in three-dimensional space and projecting light sources onto rapidly moving particles, or forming voxels by instantly irradiating very strong intensity lasers to explode light in the air. These types of displays require physical space to confine particles, and their use is limited due to the volume of control devices, or they pose risks of user injury due to the use of strong intensity light sources, making commercialization difficult.
One way to overcome these limitations is to apply stretchable platforms to displays. Stretchable platforms are technologies where objects or surfaces elastically expand or contract, changing their shape or function, characterized by expanding or reducing surfaces using elastic materials or mechanical structures. This technology can be utilized as one of the methods to secure space for implementing voxels. If it is possible to maintain a two-dimensional screen basically and expand to three-dimensional space when necessary, it would be possible to secure space for confining particles while maintaining portability, resulting in very high space utilization. Thus, stretchable platform technology has great potential for application to spatial display implementation in various ways based on new concepts and imagination.
Hologram technology has consistently received commercial attention as another method for creating spatial displays. Hologram technology has the advantages of being thin, light, and capable of expressing three-dimensional stereoscopic images in space, but it currently faces technical limitations. For three-dimensional information expression, the angle from which users view must be considered. The more information the displayed image contains for each viewing position and angle, the more natural stereoscopic effect can be implemented in hologram displays. However, to express spatially continuous information, the amount of information to be expressed increases dramatically compared to existing two-dimensional flat images, and the display resolution must also increase significantly compared to existing displays. Therefore, current hologram display implementation research remains limited to methods such as narrowly restricting the area where images can be expressed or fixing the viewing position to limit the amount of information.
As one method to solve the problems of the aforementioned technologies, we can consider spatial displays that combine the advantages of modern display technologies. For example, if smart glasses and hologram displays are combined, the smart glasses worn by users can analyze and transmit the user’s current position and gaze, and the display can show only the information needed at that moment, which is expected to greatly reduce information processing volume. Also, in single-user environments, artificial intelligence technology can be applied to information processing to pre-calculate information within the predicted range of user movement, reducing processing volume. When the number of users increases, problems can be solved by considering the redundancy of angle-specific information to reduce unnecessary information volume and optimize information processing methods. At this time, if hologram displays are implemented in stretchable form, it would be possible to maintain a small size normally and display large-volume spatial images only when necessary.
When spatial display technology is implemented, the boundaries between screens and surrounding environments will be lowered, making it possible to implement Mixed Reality where virtual and reality can be freely crossed through screens. The way we utilize space will fundamentally change, and innovative changes are expected across industries including education, healthcare, entertainment, construction, and manufacturing.