Screen size is determined by the media being presented. For most presentation such as PowerPoint slides and computer based information. Image height = 1/6 the distance between the screen and the farthest viewer. For video only presentations (e.g. videotape playback, videoconference) Image height = 1/8 the distance between the screen and the farthest viewer For 35mm/70mm motion picture presentations(e.g. screening rooms, theaters etc.) Image height = 1/4 the distance between the screen and the farthest viewer Screen widths is a function of the aspect ratio (height:width) of the media being presented. Video and computer data has an aspect ratio of 3:4 (e.g. the screen width equals 1.33 x height) 35mm slides have an aspect ratio of almost 2:3 (e.g. the screen width equals 1.48 x height) Note: this is for horizontally "landscape" formatted images; vertical "portrait" formatted slide images will require a screen height equal to screen width. 35mm/70mm film has an aspect ratio of 2:35:1 (e.g. the screen width equals 2.35 x the image height) In certain spaces, the ability to display two images side-by-side dictate the installation of a double-wide screen or two screens, This provides the ability to compare different media and utilize markerboards simultaneously. The ceiling height in all areas is adequate to allow the bottom of a projected image to be displayed at a minimum of 3' to 4' above the floor to allow for clear viewing above the heads of other audience members.