VIVOTEK
User's Manual - 75
Take the following into consideration when using this feature:
1. Operational requirement: Identify a human or a human face.
2. Why human face? There are less variances in the size of a face than that for limbs and body. Human
face is normally 16cm wide.
3. The recommended pixel number is, 40 to 80 for facial identification; or 100 pixels per foot (30.48cm)
3-1. One example is a human face in retail.
3-2. Another example is a doorway:
If the requirement is 100 pixels per foot, to detect a person passing through a door, the camera
will have to cover 700 pixels throughout the length of a doorway. This application aims to identify a
subject passing through a specific area.
4. Other factors may include that a person will move in your area of interest: The face may not always
face the camera.
5. Details can be affected by weak lighting or the view angle. Therefore, higher the pixels, higher the
chance you can identify the subject.
6. The pixel calculator visual tool looks like the following.
Pixel Calculator
Pixel Calculator
1
2
With the visual tool, you can estimate a coverage area, the distance from the subject, and place a ruler
or an object of known size. You can then draw a calculator frame to cover the subject of your interest.
The calculated numbers will be listed at the lower screen. You will then understand if the current
setting fulfills your requests for the number of pixels.
