Professional Lighting & Production - Summer 2019 | Page 32

Focus
The minimum and maximum distances from
the projector to display that will provide a
sharp picture.
Keystone
Keystoning is an effect that occurs when a
projector is not exactly perpendicular to the
display surface, thereby creating an image that
is not rectangular. There are several solutions
available to prevent keystoning.
LCD
Liquid Crystal Display is a display device for
generating colour images using a matrix
of LCD pixel elements. Each pixel element
consists of three sub-pixels and an RGB colour
filter of red (R), green (G), and blue (B). By
controlling the voltage to each sub-pixel, each
cluster of RGB pixels can create a full spectrum
of coloured light. In addition to projectors,
LCDs are used in flatscreen displays, cameras,
laptops, and other display devices.
Rear Projection
Rear-screen projection displays, where the pro-
jector is located behind the screen and thus
not in the front-of-house area, allow for greater
control of ambient lighting. This ultimately
means better picture brightness and contrast
ratios, and less eye fatigue for operators.
FRONT OR REAR PROJECTION?
Benefits of front projection:
• Generally easier to install
• No dedicated projection room or area
required
• Space-effective design
• More cost-effective solution
• Enhanced mobility of the projector and
surface
A FUTURISTIC SPECTACLE
ON A HISTORIC STRUCTURE
PL&P Fall 2018
Constructed between 1884 and 1887, the Old
Post Office in Cambridge, ON, is an elegant
two-and-a-half-storey stone building featuring
symmetrical twin facades and a striking clock
tower all finished with local limestone.
To celebrate its $14.9-million renovation
and reopening as the latest Idea Exchange
location – a “digital library” and collaborative
hub – Toronto’s Westbury National developed a
32 | Summer 2019
Throw Distance
Throw distance is the measurement from
the projector’s lens to the screen. A projector
with a zoom lens will have a range of throw
distances for any given image size, while a
projector without a zoom lens will only be able
to project one image size at a given distance
from the display surface.
Throw Ratio
The width of the image (W) relative to the
throw distance (D) is known as the throw ratio
(D/W). For example, one of the more common
projector throw ratios is 2.0. This means that
for each foot or metre of image width, the
projector needs to be two feet or metres away
(D/W = 2/1 = 2.0).
LED PANELS
An LED display is a flat panel display that
uses an array of light-emitting diodes (LEDs)
as pixels for a video display. Their brightness
makes them ideally suited to outdoor or high
brightness applications. Also, LED displays
are capable of providing general illumination
and light effects in addition to visual display,
as is being increasingly seen in stage lighting
and other more decorative applications (as
opposed to informational applications).
There are two types of LED panels:
• Conventional, which uses discrete
LEDs
• Surface-Mounted Device (SMD)
panels.
Benefits of rear projection:
• Enhanced contrast and image brightness
• Better performance in high-brightness
applications
• No shadows from presenters or viewers
cast onto the screen
• Projection equipment is hidden behind
the screen
• Noise-free operation
projection-mapped multimedia show displayed
on the building’s one-of-a-kind façade with the
goal of driving residents and tourists into the
library and downtown core over the summer of
2018 and beyond.
The 20-minute show, anchored by four
Christie Boxer 2K30 3-DLP projectors, takes
viewers on a trip through time, exploring the
history and legacy of the building, the city, and
the country. Key moments that showcase the
technology’s capabilities include the building
becoming a digital EQ meter that moves in
perfect synchronization with the soundtrack, or
Outdoor screens have traditionally been
built around discrete LEDs, also known as indi-
vidually-mounted LEDs. A cluster of red, green,
and blue diodes is driven together to form
a full-colour pixel, usually square in shape.
These pixels are spaced evenly apart and are
measured from centre to centre to calculate
pixel resolution.
Most indoor screens on the market are
built using SMD technology, though this trend
has been extending to the outdoor market
lately. An SMD pixel consists of red, green, and
blue diodes mounted in a single package,
which is then mounted on the driver PC board.
The individual diodes are smaller than a pin-
head and are set very close together.
Dot Pitch
Is a specification for a pixel-based device
that describes the distance between dots
(sub-pixels) on a display.
Nit
The nit is a comparatively small unit of bright-
ness that measures light emitted from any
device. A typical active-matrix LCD panel has
an output between 200 and 300 nits. For ex-
ample, in order for an outdoor LED sign to be
visible, it must generate a minimum of 5,000
nits, being that the sun emits approximately
4,000 nits during daylight.
Pixel Pitch
In the case of an RGB colour display, the de-
rived unit of pixel pitch is a measure of the size
of a triad plus the distance between triads.
Viewing Angle
In display technology parlance, viewing angle
is the maximum (or widest) angle from the
centre of the display at which a display can be
viewed with acceptable visual performance.
Usually, that means the angle at which the
brightness of the display is equal to 50 per
cent of the frontal luminosity.
a library scene where the spines of the books
on a shelf become digitized in commemoration
of the new digital library.