Zone Parameter Explanations

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Revision as of 11:28, 2 November 2013 by Fastolfe (talk | contribs) (Rework zone descriptions for clarity and concision)
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Zone Parameter Explanations

  • Note: This area is complex and needs alot of work. Please help in any way that you can!

Name

Each Zone can be named for reference purposes. Choose a name that helps you identify your zones.

Type

  • Active
    Triggers an alarm when motion is detected within it. This is the zone type you'll use most often, and which will be set for your default zone. Only Active and Exclusive zones can trigger an alarm.
  • Inclusive
    Adds to an alarm score when motion is detected within it, but does not trigger an alarm by itself. Use this for regions that are prone to false positives, but still provide a useful motion signal. An example could be a window, or a plant or a tree that moves a lot, but where interesting motion could still occur in front or behind it. In this case you would use an Active zone to monitor just the areas you want to trigger an alarm for, and an Inclusive zone to watch the areas you don't, perhaps with less sensitive detection settings. This zone type is only effective for alarms generated by Active zones, not Exclusive zones.
  • Exclusive
    Triggers an alarm when motion is detected within it, unless an alarm was triggered by an Active zone. This allows you to specialize detection of events for different types of motion. For instance in the camera covering my garden I keep watch for a hedgehog that visits most nights and scoffs the food out of my cats bowls. By creating a sensitive Exclusive zone in that area I can ensure that a hedgehog alarm will only trigger if there is activity in that small area. If something much bigger occurs, like someone walking by it will trigger a regular alarm and not one from the Exclusive zone. Thus I can ensure I get alarms for big events and also special small events but not the noise in between.
  • Preclusive
    Precludes an alarm if motion is detected within it. If an alarm is raised by an Active or Exclusive zone, and motion is also detected in a preclusive zone, no alarm will occur for any zone. This is useful for detecting large-scale lighting and shadow changes, camera motion, or other types of expected motion that may extend into an Active zone but you don't want to trigger an alarm. Some of this could be accomplished instead by adjusting the settings of an Active zone (such as limiting the maximum number of alarm pixels), but this may be difficult in some situations, such as the sun coming out suddenly. Preclusive zones are designed to be fairly small, even just a few pixels across, with quite low alarm thresholds. They should be situated in areas of the image that are less likely to have interesting motion occur such as high on a wall or in a corner. Careful placement is required to ensure that they do not cancel any genuine alarms or that they are not so close together that any motion just hops from one Preclusive zone to another. As always, the best way is to experiment a little and see what works for you.
  • Inactive
    Suppresses the detection of motion within it. This can be layered on top of any other zone type, preventing motion within the Inactive zone from being effective for any other zone type. This is equivalent to cutting a hole in any other zone that overlaps the Inactive zone. Use this to cover areas in which nothing notable will ever happen or where you get false alarms that don't relate to what you are trying to monitor.

Units

  • Pixels - Selecting this option will allow many of the following values to be entered (or viewed) in units of pixels.
  • Percentage - Selecting this option will allow may of the following values to be entered (orviewed) as a percentage.

Minimum X - Minimum Y - Maximum X - Maximum Y

Use these parameters to define the X,Y coordinates of the corners of the zone that is to be defined.

Alarm Colour

These parameters can be used to indvidually colorize the zone overlay pattern. By default, red is the active zone and green is the ??? zone.

Alarm Check Method

  • Alarmed Pixels -

Choosing this Check Method will grey out many of the available parameters. This can simplify the tuning process, and could possibly be a better starting point for learning to adjust the many advanced parameters that are enabled with the other options. Its recommended that you start with this method.

  • Filtered Pixels -

Choosing this Check Method opens up the Filtered parameters for adjustment in addition to the Alarmed Pixels above. This should give more accuracy, once you know how to adjust the various parameters and assist with eliminating false alarms and triggering on desired conditions.

  • Blob Pixels -

Choosing this Check Methos opens up all of the available parameters. Enabling Blobs provides one more analysis for determination of what is a valid alarm and what is not.

Minimum Pixel Threshold

These setting are used to define limits for the difference in value between a pixel and its predecessor in the reference image.

This value (and the Maximum value as well) defines the amount of change that a single pixel must undergo, from the prior image (the reference image) and the current image, in order for the pixel to have been considered to have changed.

Small abberations in lighting or auto exposure camera adjustments may cause the explicit value of a pixel to vary by small amounts from image to image. This parameter allows you to set the limits of what will be considered a "changed pixel". For example, if your camera points to a blank white wall, and you raise a black colored item into view, then the change in any one pixel will be great, indeed, extreme. If however, you raise a white piece of paper, then the change that an individual pixes sees will be more subtle. Setting this minimum value too high, may allow a white cat to walk undetected across the view of the white wall.

Maximum Pixel Threshold

See the Minimum Pixel Threshold (above) for some explanation.

The default value for this parameter is 0% or 0 (zero) pixels, which disables the check. In other words, a pixel that changes from extreme white to extreme black will always be considered to be changed. This value is probably best left at a value of 0 (zero).

Minimum Alarmed Area

This setting controls the minimum amount of alarmed pixels (read above) needed to trigger an alarm. Depending on the size of the object you are trying to capture, a value too low may cause false alarms, while a value too high might not detect small objects. You will probably need to experiment to find a value that doesn't trigger many false alarms but still able to detect small objects such as dogs or cats.

Maximum Alarmed Area

This setting controls the maximm amount of alarmed pixels (read above) needed to trigger an alarm. The default value for this setting is 0, which disables the check and is probably best to leave it that way.

Filter Width and Filter Height (pixels)

This parameter is always specified in Pixels, even when Percentages are the selected units.

This parameter defines a group of pixels and should always be an odd number.

3 x 3 is the default value, and 5 x 5 is also suggested as another valid option. It is suggested that these numbers be small in number.

Minimum Filtered Area

  • This value should always be equal to or less than the Minimum Alarmed Area

Maximum Filtered Area

  • This value should always be equal to or less than the Maximum Alarmed Area

Minimum Blob Area

  • The following Blob parameters are only available if you have selected "Blobs" as the "Alarm Check Method" above.

When two or more Filtered areas touch or share a boundary, they probably should be evaluated as one contiguous area and not as separate entities. A Blob is the coalesced or consolodated area of multiple filtered areas.

The Minimum blob area the smallest area that would be considered to be a blob.

Maximum Blob Area

This parameter is probably best left at the default value of 0 (zero) or disabled.

Minimum Blobs

Normally, you would want any single blob to trigger an event, so the default value of 1 (one) should suffice. In some circumstances, it may benefit to have only one blob NOT trigger an event, in which case, setting this value to 2 or higher may serve some special purpose.

Maximum Blobs

I believe that the usefulness of this parameter is negligible. Normally set to 0 (zero), it is probably best left at that value.