MediaXtreme MediaZone
Keywest Technology
14563 W. 96
th
Terrace
Lenexa, Kansas 66215
800.331.2019
www.keywesttechnology.com
139
23 Mar 2009
Change 06
Appendix F
X-Warp Geometry Correction
Digital Signage applications continue to increase in number globally—video presentations
continue to be a mainstay of the business meeting and conferences world wide. Video projectors
are the tool of choice for presentations and are occasionally used for digital signage.
Projectors allow for displays much larger than plasma or LCD and at an affordable cost. Flat
panel displays can run $10,000 for a quality 61” device, and currently are limited to that size or
smaller (although sizes upwards of 100” are imminent). LED walls offer huge sizes (displays at
stadiums, outdoor signage on buildings, etc…) but at a hefty price—$2000 per square foot for
coarse resolution at 22mm distance between LEDs up to $5000 per square foot for 3mm LED
placement (higher resolution). To achieve a 10’ or greater diagonal display, the choices are
either LED at $64,000 to $160,000 with limited close-viewing resolution or projection in a price
range of $2,500 to $10,000 depending upon the quality of the projector and screen material.
Simple Geometry
While economy is the attractive feature of projectors in large format applications, the projector
itself is the major con—especially in digital signage. The physical characteristics of projection
mandate that the projector be placed as close to perpendicular to the screen as possible and at a
“throw distance” that fills the screen. In some presentation applications the hindrance of placing
a table in the middle of the room shooting straight onto a screen is not significant…but in an
open venue, this is rarely viable and in staging applications, the desired placement of a projector
would be hidden from view.
The projector needs to be placed out of the general traffic flow for simple viewing angle reasons
but also for safety reasons. Rear projection can help, but if the screen that needs to be filled is
large enough, a significant amount of room behind the projector must be allocated to give the
projector throw distance.
The need then is to place the projector in a location other than “straight on”. Most projectors,
even the lowest cost models, have basic alignment functions such as keystone or trapezoid
compensation. These controls allow the projector to be imperfect in placement; however any
placement that exceeds the functional limits of the projectors adjustments requires geometrical
compensation devices.
There are very few hardware based video processor devices that perform scan-conversion as well
as some geometric conversion functions. Such device adds at the minimum $2,500 to the
installation per channel. The bill of materials for such an application consists of a projector, a
screen, a playback device (media player, PC, other), and a video processor.
