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Before personal computers, they were 35 mm slides viewed with a slide projector [1] or transparencies viewed with an overhead projector. In the digital age, a slide most commonly refers to a single page developed using a presentation program such as MS PowerPoint, Apple Keynote, Google Slides, Apache OpenOffice or LibreOffice.
After such a file is created, typical operation is to present it as a slide show using a portable computer, where the presentation file is stored on the computer or available from a network, and the computer's screen shows a "presenter view" with current slide, next slide, speaker's notes for the current slide, and other information. [85]
A projector or image projector is an optical device that projects an image (or moving images) onto a surface, commonly a projection screen. Most projectors create an image by shining a light through a small transparent lens , but some newer types of projectors can project the image directly, by using lasers .
A webcam is mounted on arms to operate a document camera, allowing it to be positioned over a page. The camera connects to a projector or similar video display system, enabling a presenter to write on a sheet of paper or display a two- or three-dimensional object while the audience watches. Larger objects, for instance, can be positioned in ...
The LCD system did not have a light source of its own: it was built on a large "plate" that sat on top of the projector in place of transparencies. This provided a stop-gap solution in the era when the computer was not yet a universal display medium, creating a market for LCD projectors before their current main use became popular.
In the mid-1980s developments in the world of computers changed the way presentations were created. Inexpensive, specialized applications now made it possible for anyone with a PC to create professional-looking presentation graphics. Originally these programs were used to generate 35 mm slides, to be presented using a slide projector.
Parallel projection corresponds to a perspective projection with a hypothetical viewpoint; i.e. one where the camera lies an infinite distance away from the object and has an infinite focal length, or "zoom". In parallel projection, the lines of sight from the object to the projection plane are parallel to each other. Thus, lines that are ...
Projector-camera systems may also be used for artistic and entertainment purposes. [2] A pro-cam system consists of a vertical screen for implementing interpersonal space where front-facing videos are displayed, and a horizontal projected screen on the tabletop for implementing shared workspace where downward facing videos are overlapped.