Computer Output Media

 

The second part of the machine-to-man communication is mainly influenced by the devices and methods that are used to address the senses described in sections 2.1.2 -- 2.1.4 . Despite the technical limitations that still exist today, there are a number of ways for machines to communicate with their users. Some of them will be presented in the following sections.

Output modalities

Under output modalities or computer output media, we understand the media (devices) and modalities (communication channels) which are used by computers to communicate with humans. As the communication channels for computer output are the same ones as those for human input (see figure 1.1 ), the following subsections are structured with respect to those in section 2.1 . Therefore, we renounce to repeat what has been said there and will instead investigate the devices and methods for the three ``main senses'' in the following.

Devices and methods for visual output

As stated before ( 2.1.2 ), the human visual system has large dynamic ranges. Presently there are many tools available for generation of stimulating the visual sense for many of its properties, with computer displays being the predominant output communication channel. Modern computer display technology can generate stimulations which cover full or significant part of practical dynamic ranges for visual properties like color and temporal resolution. While the computer displays are far from being completely 'transparent', they get high marks for their overall perceptual impact. In the near future one can expect full integration of high-quality video and TV-like capabilities with a computer-like contents, integrating and improving the information output from the different sources.

The biggest single deficiency in output devices appears in the spatial vision stimuli, as displays capable of covering a high-resolution wide field of view and especially of 3D visualization are uncommon. The display resolution will be still growing and its aspect ratio may change in the future to the 16:9 from the current 4:3, allowing for greater perceptual involvement. However, stereoscopic and 3D visualization need new solutions to become practical (the difference between the stereoscopic vision and 3D is that in the latter motion parallax is carried on, that is the objects will look differently from different angles of view). The lack of spatial effects has diminishing effect on the sensation of reality and involvement in the content of the scene. A more advanced aspect of this problem is the lack of full immersion in visual scenes, which is being tried to be solved with virtual reality devices. The virtual reality technology in its present form is nonergonomic in the sense that it can be used only for a limited time during one session. Wide-field high-resolution visualization with spatial effect would be optimal from the ergonomic point of view.

Devices and methods for acoustical output

In this section methods for presenting information via acoustical means will be presented. In real life humans are able to get a lot of information via the auditory modality. The communication by the means of speech is practiced every day. Even if sometimes we are not conscious about that, we use a lot of non-speech sounds in daily life to orientate and to get precise knowledge of the state of the environment. When acoustical output is used in technical interfaces the way we use sound every day life is adapted to serve as a powerful tool for information transfer. In the following text the underlying concepts or technologies will be presented. It is not the aim of this text to list different synthesis algorithms or to discuss the underlying hardware problems, although they are limiting the widespread use of some interesting methods. The existing audio hardware found in PC and recent workstations will be presented briefly.