Video Motion Reference windows
A video motion window can trigger unwanted events that have not been caused by
moving objects, but by changes in image brightness. These changes may occur
when switching lights on or off, or when moving clouds and sunny sky lead to
rapid changes in illumination. A reference window can prevent these unwanted
video motion events from occurring.
Reference windows represent a special type of video motion window. Much like
video motion windows, reference windows recognize changes in pixel brightness,
but they will not trigger an event, they prevent events from being triggered. For
example, if a video motion window and a reference window simultaneously
detect changes in pixel brightness, the camera will not trigger an event and
the camera will neither send alarm messages nor start image recording!
Reference windows are defined just like video motion windows; adding an excla-
mation mark (!) at the beginning of the line in the Video Motion Definitions (VM)
field will make this definition a reference window:
# Example reference window
!0,358,456,10,40,20,25
Reference windows are shown in the camera images as yellow dotted frames.
The following procedure has proven to produce the best results:
1) Define video motion windows as required and adjust the parameters
accordingly (
area
,
max. area
, etc.).
2) Create a small reference window (e.g. 25 x 25 pixels) within an area with
solid colors (wall of a building, wallpaper, asphalt, etc.) that changes bright-
ness if the light is switched on or the clouds are moving (i.e. if illumination is
changing). Make sure that you are not using an area that could be changing
due to moving objects.
Make sure that the
area
,
max. area
and
sensitivity
parameters are set to the
factory defaults.
3) Create a small video motion window with exactly the same dimensions and
the same position as the reference window. To do this, simply copy the com-
plete line of the reference window definition, add it beneath the reference
window definition in the Video Motion Definitions (VM) text field and
remove the exclamation mark.
Make sure that the
area
,
max. area
and
sensitivity
parameters are set to the
factory defaults.
If the light is switched on, the brightness changes both within the reference window
and the identical video motion window. Subsequently, the reference window will
prevent the camera from triggering the VM event.
© MOBOTIX AG • Security-Vision-Systems • Made in Germany
www.mobotix.com • sales@mobotix.com • 10.10.2006
164/288
Software Camera Manual Part 2
Reference windows help
avoid false alarms
To Next Page
Loading...
