Instrukcja obsługi Toshiba IKS-WB9518


Przeczytaj poniżej 📖 instrukcję obsługi w języku polskim dla Toshiba IKS-WB9518 (4 stron) w kategorii Kamera monitorująca. Ta instrukcja była pomocna dla 7 osób i została oceniona przez 2 użytkowników na średnio 4.5 gwiazdek

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Pixels Per Foot
A beginner’s guide to PPF
What is the role of PPF in selecting an IP camera?
Ensuring high quality surveillance IP video can be a challenge — beginning with specifying cameras to achieve the level of quality
needed for operational requirements. The traditional way of specifying surveillance cameras was by resolution, for example
selecting a 1080p model over a 720p for a critical area. However, this method has proven inexact, resulting in too much or too lit-
tle quality. A newer, more accurate way is to specify pixels per foot (PPF) density. While some may find this new method confus-
ing or complex, the mathmatics behind it are actually quite simple as this brief will explain.
CALCULATING PPF
The formula for calculating PPF is . Let’s look at an example: the installer has aHorizontal Pixels divided by Field of View width
2MP IP camera with a resolution of 1920 (H) x 1080 (V). The Horizonal Field of View for the area being monitored is 100 feet wide.
Therefore, PPF is 19.2 based on 1920 divided by 100. But is 19.2 PPF enough? Is it too much? Let’s look:
Toshiba America Information Systems, Inc. Surveillance & IP Video Products www.toshibasecurity.com | |
19.2 PPF 40 PPF More than 40 PPF
Image lacks detail with
little or no facial feature
recognition and a non-
readable license plate.
Not all facial features
can be made out. Plate
numbers can be read
but not state.
Clearly can see all
facial features, and can
read license plate num-
bers and state.
Obviously, the more pixels, the higher the resolution and the easier it is to recognize faces and license plates. The down-
side is that higher resolution requires more bandwidth and storage space.
Toshiba America Information Systems, Inc. Surveillance & IP Video Products www.toshibasecurity.com | |
PPF DECREASES AS DISTANCE INCREASES
The “field of view” or FOV refers to the physical limits on the visual boundaries you are viewing. In the case of a security camera,
the field of view is impacted by two factors:
1. the focal length of the lens
2. the size of the imaging sensor
The lens determines the field of view captured. A wide angle lens will view objects that are close to the camera, while a telephoto
lens will see objects further away. The higher the focal length (mm) of the lens, the more magnification. The lower the number, the
wider the angle of view. When you use a high resolution camera you must select a high resolution or Mega-pixel lens that will
maintain the high resolution. We suggest using one of the many available online lens calculators that will help determine the dis-
tance to the object, width of the field of the view and lens focal length (f in mm).
The is the distance across the image while refers to the height of the image. Typically, the vertical fieldhorizontal field vertical field
of view is approximately 70 percent of the horizontal field of view. Therefore, the total field of view is more like an angular field
where the further you get from a camera, the wider the field becomes and the lower the PPF. The FOV must be set up so that
the widest scene width (furthest away) still gives the correct PPF, especially for good facial images. In general, a PPF of 10 is
usable for tracking of motion. A PPF of 20 will work for general security applications, while a PPF of 40 provides forensic level
details. A PPF of 60 or above delivers highly detailed images. Identifying a face in some circumstances may require a PPF over
200 to capture minor details like scars, eye color or tattoes, depending on lighting.
PPF CASE STUDY: THEFT AT CAR PARTS WAREHOUSE
A large car parts warehouse located in the Southwest was
experiencing a raft of catalytic converter thefts. It hired a video
surveillance firm to install Toshiba IP video surveillance cam-
eras to monitor three entrances from its parking lot (marked
with the red circles) and to record license plate numbers.
ENTRANCE ONE
At entrance one the FOV is 25 feet, the working distance is 50
feet and the height is 35 feet. To calculate the PPF based on
three different camera models: 1902 x 1080; 1280 x 1020; and
640x480, we use these formulas.
1920 x 1080 (2MP) Camera
PPF: 1920/25 = 76 PPF
Result: High detail
1280 x 1024 Camera
PPF: 1280/25 = 51 PPF
Result: Forensic Level
640 x 480 camera
PPF: 640/25=25 PPF
Result: General Security
25 Feet
50 Feet
ENTRANCE TWO
At entrance two the FOV is 25 feet, the working distance is
100 feet and the height is 35 feet. To calculate the PPF based
on three different camera models: 1902 x 1080; 1280 x 1020;
and 640x480, we use these formulas.
1920 x 1080 (2MP) Camera
PPF: 1920/25 = 76 PPF
Result: High detail
1280 x 1024 Camera
PPF: 1280/25 = 51 PPF
Result: Forensic Level
640 x 480 camera
PPF: 640/25=25 PPF
Result: General Security
25 Feet
100 Feet
Toshiba America Information Systems, Inc. Surveillance & IP Video Products www.toshibasecurity.com | |


Specyfikacje produktu

Marka: Toshiba
Kategoria: Kamera monitorująca
Model: IKS-WB9518

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