Defining Zones
Zones are used for image analysis in ZoneMinder and Zone definition has a
 significant effect on the effectiveness and performance of a ZoneMinder
 server. An optimally configured Zone will reduce CPU processing
 requirements as well the number of unintended saved events. Therefore, it
 is important to understand the concepts behind the many Zone types as well
 as Zone parameter settings and their proper use. From the Console
 interface, click on the number in the Zones column of any monitor to enter
 the Zone view.



Zone View
	
	../_images/define-zone-list.png
	Defining Zones - Zone View

An illustrative (but not very practical) example is shown above to help
 introduce the items found in the Zone View.



[A] Monitor View
Shows the selected monitor live view with overlay of existing defined
 Zones and their respective regions. An existing Zone can be edited by
 clicking on its region. Note that the different types of Zones are
 depicted with specific colours. The default Zone type is Active shown in
 red, Inclusive Zones are orange, Exclusive Zones are purple, Preclusive
 Zones are blue, Inactive Zones are grey and Privacy Zones are opaque
 black. The definition for each Zone type is explained below in the Zone
 Parameters section.

[B] Zone List
Lists the existing defined Zones for the monitor along with their Type and
 Area given in both number of pixels and area in percent relative to the
 entire monitor image. Knowing the number of pixels in a Zone region will
 be necessary for setting many of the Alarm Check related parameters. An
 existing Zone can be edited by clicking on its Name.

[C] Mark
Used for deleting Zones. Check each box of the Zone to be deleted and
 click DELETE.


[D] +ADD NEW ZONE
Click +ADD NEW ZONE to add a new Zone for the monitor.


[E] Status
Displays basic monitor status: alarm state, viewing FPS, capturing FPS and
 analysis FPS.



Zone Parameters
To modify an existing Zone, from the Zone View, click on either the Zone
 region or Zone Name. After making any changes to the Zone Parameters,
 click SAVE.
	
	../_images/define-zone-parameters.png
	Defining Zones - Zone Analysis Parameters

The right side of the display contains the Zone analysis parameter
 information. This is where the analysis type and various tuning parameters
 can be set. The user can manually fine tune the analysis settings or if
 desired various Preset options are available.


[A] Name
Each Zone can be named for reference purposes which will be used for
 logging and debugging. Choose a Name that helps uniquely identify the
 Zone.


[B] Type
The Zone Type determines the image processing method and is one of the
 more important concepts in ZoneMinder.


Active: This is the default Zone type and triggers an alarm when motion is
 detected within it. Most Zones will use this type. Only Active and
 Exclusive Zones can initiate the triggering of an alarm.


Inclusive: This Zone type can be used for any Zones that you want to
 trigger an alarm only if at least one Active Zone has already triggered
 one. For example this could cover an area of the image like a plant or
 tree which moves a lot and would trigger many alarms. Perhaps this is
 behind an area to be monitored though, in this case create an Active Zone
 covering the non-moving parts and an Inclusive Zone covering the tree
 perhaps with less sensitive detection settings. If something triggers an
 alarm in the Active Zone and also in the Inclusive Zone they would both be
 registered. The resulting alarm would be larger than if it had been
 blanked out altogether.


Exclusive: Triggers an alarm when motion is detected within it, as long as
 no alarms have already been triggered in an Active zone. This is the most
 specialized of the Zone types. For instance for the camera covering my
 garden I keep watch for a hedgehog that visits most nights and scoffs the
 food out of my cat’s 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, it can be ensured that alarms for big events are captured as
 well as special small events. Any others are ignored.


Preclusive: If triggered this Zone type will preclude an alarm being
 generated for that image frame. So motion or other changes that occur in a
 Preclusive Zone will have the effect of ensuring that no alarm occurs at
 all. The application for this Zone type is primarily as a shortcut for
 detecting general large-scale lighting or other changes. 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 motion occur such as high on a wall or in a
 corner. Should a general illumination change occur they would be triggered
 at least as early as any Active Zones and prevent any other Zones from
 generating an alarm. Obviously, 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.
 Preclusive Zones may also be used to reduce processing time by situating
 one over an Active zone. The Preclusive Zone is processed first; if it is
 triggered the rest of the Zones will not be processed. See Extend Alarm
 Frame Count below for a way to hold the Preclusive Zone active for an
 extended period.


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. Use Inactive
 Zones to cover areas in which nothing notable will ever happen or where
 false alarms would occur that don’t relate to what is being monitored.
 Inactive Zones may be placed over other Zones to reduce detection areas.
 As a general practice Zones should abut each other instead of overlapping
 to avoid processing of the same area more than once.


Privacy: Blackens the pixels within it to make the region completely
 opaque. This can be used to hide regions within the image if the situation
 does not allow another solution. This Zone type is different from all the
 others in that it gets processed as soon as possible during capture (even
 before the timestamp is added to the image) and is not part of the
 analyzing process. Note that if a Privacy Zone is added, changed or
 deleted, the changes will not be seen in the image until the capture
 process is restarted. This is done automatically, but generally takes a
 few seconds.


[C] Preset
The Preset chooser sets sensible default values for the Zone parameters
 based on computational needs (fast or best) and sensitivity (low, medium,
 high). It is not required to use a Preset but if one is selected, the
 parameters can be subsequently changed as desired. For a ZoneMinder server
 running on modern equipment with few monitors, the ‘Best, high
 sensitivity’ Preset can be chosen as a good starting point.

It is important to understand that the available Presets are intended
 merely as a starting point. Because every camera view is unique, they are
 not guaranteed to work properly in every case. Presets tend to work
 acceptably for indoor cameras where the objects of interest are relatively
 close and typically there are few or no unwanted objects moving within the
 camera view. Presets, on the other hand, tend to not work acceptably for
 outdoor cameras where the field of view is typically much wider, objects
 of interest are farther away and changing weather patterns can cause false
 triggers. For outdoor cameras the motion detection will need to be tuned
 for each Zone to obtain desired results.


[D] Units
Selects the method for entry of Zone area parameters.

Pixels: Selecting this option will allow the analysis parameters related
 to area to be entered or viewed in units of Pixels. The advantage of using
 Pixels for area parameters is that it allows a more fine-grained control
 of the settings.

Percentage: Selecting this option will allow the analysis parameters
 related to area to be entered or viewed as a Percentage. These Percentage
 values refer to the area of the Zone region and not the monitor image as a
 whole. This facilitates the estimation of area in most cases.



[E] Alarm Colour
These parameters can be used to individually colour the Zone alarm overlay
 pattern. Alarms in this Zone will be highlighted in the alarm colour. The
 RGB colour system is used with a range of values of 0-255 for each primary
 colour. This option is irrelevant for Preclusive, Inactive and Privacy
 Zones and will be disabled.


[F] Alarm Check Method
There are three Alarm Check Methods. They are applied sequentially and are
 layered. In AlarmedPixels mode, only the AlarmedPixels analysis is
 performed. For FilteredPixels mode, the AlarmedPixels analysis is
 performed first, followed by the FilteredPixels analysis. Using the Blobs
 mode, all 3 analysis methods are performed sequentially. An alarm is
 triggered only if all of the enabled analysis mode criteria are met. For
 performance reasons, as soon as the criteria for one of the analysis modes
 is not met, the alarm checking for the frame ends. Because the subsequent
 modes each require progressively more computations, it is a good idea to
 tune the parameters in each of the activated layers.


AlarmedPixels: Alarmed pixels is the first layer of analysis and is always
 enabled. It is recommended to start with this method and move on to the
 subsequent methods once the effects of the related analysis parameters are
 understood. In the AlarmedPixels mode, 2 parameter categories are
 available for tuning: Min/Max Pixel Threshold, and Min/Max Alarmed Area.


FilteredPixels: Selecting the FilteredPixels Alarm Check Method adds
 another layer of analysis to the AlarmedPixels check along with 2
 additional parameter categories for tuning. This layer works by analyzing
 the alarmed pixels identified in the first layer. Alarmed pixels are
 disregarded, in this and future layers if enabled, if they are not in
 groups of a minimum small square size. Primarily, this filtering removes
 isolated alarmed pixels that may be artifacts of the camera, lens, or
 compression.


Blobs: When two or more Filtered areas touch or share a boundary, it is
 sensible to evaluate the regions as one contiguous area instead of
 separate entities. A Blob is a contiguous area made up of multiple
 filtered areas. Whereas FilteredPixels is useful for excluding parts of
 the image that are not part of the actual scene, Blob filtering is better
 suited to disregarding areas of the actual scene that are not of interest.


	
    ../_images/define-zone-alarm-check.png
    Alarm Check Method Comparison (Left to Right): AlarmedPixels,
 FilteredPixels, Blobs

The images above serve to illustrate Alarm Check Methods. AlarmedPixels is
 performed first on the image on the left with a person entering the Zone
 region. Pixels in white exceeded the Minimum Pixel threshold. However, as
 one can see there are many pixels included that are not part of the person
 to be detected. This is due to the motion of the person across the Zone
 region relative to the reference frame. FilteredPixels Alarm check is
 performed next which has the effect of eliminating many of the residual
 pixels that are not of interest. Blob Alarm Check is the final process
 performed and combines contiguous regions of the FilteredPixels. The
 result of this final process can be seen as a green Blob outline of the
 person detected in the final image on the right.


[G] Min/Max Pixel Threshold (0-255)
Used by AlarmedPixels Alarm Check. In the AlarmedPixels layer of analysis
 each individual pixel of the image is compared to the current reference
 image. Pixels that are different from the reference image are considered
 alarmed pixels. However, small aberrations 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 sets the limit for what
 will be considered a changed pixel. For example, if the camera points at a
 blank white wall and a black coloured item is raised into view, then the
 change in any one pixel will be extreme. If however, a white piece of
 white paper is raised then the change in an individual pixel will be much
 smaller.

The Minimum Pixel Threshold setting should be high enough to prevent minor
 lighting, imaging, or compression changes from triggering an alarm. A good
 starting point for the Minimum Pixel Threshold is 40, meaning that the
 difference in pixel value from must be greater than 40. A good default for
 the Maximum Pixel Threshold is 0 which indicates that all differences
 above the Minimum Threshold are considered a change.


[H] Filter Width/Height (Pixels)
Used by FilteredPixels Alarm Check. This parameter is always specified in
 Pixels, even when Percent is the selected Unit. It specifies the size of
 the group of pixels surrounding a given pixel that must be alarmed pixels
 for the pixel itself to be considered a filtered pixel. The width and
 height should always be an odd number. The default value is 3 x 3, and 5 x
 5 is also suggested as a sensible alternative. Avoid using large numbers
 for the width and height of the filter area. When using the Blobs Alarm
 Check Method, FilteredPixels can be effectively disabled by setting either
 the width or height to a value less than 1.


[I] Zone Area
Zone Area is a display only parameter and is calculated from the Zone
 Regions which is described in the section below. When Units are set to
 Percent, the Zone Area displays the area of the Zone region relative to
 the entire monitor image. When Units are set to Pixels, the Zone Area
 displays the number of pixels contained in the Zone region. Note that the
 Zone Area and pixel count can also be found on the main Zone View. All 3
 Min/Max Area parameter groups are based on the Zone Area as the maximum
 value and all 3 are interpreted in the Units specified in the Units
 parameter.


[J] Min/Max Alarmed Area
Used by AlarmedPixels Alarm Check. The pixel count or area of alarmed
 pixels is used in this first layer of analysis to determine if an alarm is
 triggered. If the pixel count or area percentage is above the minimum
 Alarmed Area, but less than the maximum Alarmed Area, an alarm is
 triggered. These settings depend on the size of the object to be captured:
 a value too low may cause false alarms, while a value too high might not
 detect small objects. A good starting point for both the minimum and
 maximum are 0 and 0, indicating that any number of alarmed pixels (or any
 percentage) greater than 0 will trigger an alarm. The frame scores from
 logged events can then be used to bring the minimum up to a reasonable
 value. An alternative starting point for the minimum Alarmed Area (in
 percent) is 25% of the area that an object of interest takes up in the
 Zone region. For example, if a subject moving through the frame takes up
 approximately 30% of the Zone region, then a good starting minimum Alarmed
 Area is about 7.5%.


[K] Min/Max Filtered Area
Used by FilteredPixels Alarm Check. Applying the FilteredPixels analysis
 results in an area that is less than or equal to the Alarmed Area. Thus,
 the minimum and maximum Filtered Area parameters for alarm should be equal
 to or less than the corresponding Alarmed Area parameters, or the
 FilteredPixels analysis will never trigger an alarm. In particular, it is
 useful to raise the minimum Alarmed Area parameter until false events from
 image artifacts disappear, then setting a minimum Filtered Area parameter
 less the minimum Alarmed Area parameter by enough to capture small events
 of interest.


[L] Min/Max Blob Area
Used by Blob Alarm Check. The Blob Area parameters control the smallest
 and largest contiguous areas that are to be considered a Blob. A good
 value for the maximum area is the default of 0. Similar to the preceding
 analyses, the minimum Blob Area should be raised until events triggered
 from unwanted image artifacts disappear. There is no upper bound for the
 size of a contiguous area that will still be considered a Blob.


[M] Min/Max Blobs
Used by Blob Alarm Check. Any positive number of blobs will trigger an
 event, so the default value of 1 for Minimum Blobs works for most cases.
 In some circumstances it may benefit to have only one blob NOT trigger an
 event. In this case setting Minimum Blobs value to 2 or higher may serve
 some special purpose. A good value for the Maximum Blobs is the default of
 0. There is no upper bound for the number of Blobs that will trigger an
 event. Use the Maximum Blobs parameter to prevent alarms from events that
 show a high number of Blobs if desired.


[N] Overload Frame Ignore Count
This setting specifies the number of frames to NOT raise an alarm after an
 Overload. In this context, Overload is defined as a detected change too
 big to raise an alarm. The idea is that after a change like a light
 turning on covering the entire image which is considered too big to count
 as an alarm, it could take a couple of frames for things to settle down
 again. Depending on the alarm check method that could be:

Number of alarmed pixels > Max Alarmed Area or

Number of filtered pixels > Max Filtered Area or

Number of Blobs > Max Blobs


[O] Extend Alarm Frame Count
This field applies to Preclusive Zones only. Placing a value in this field
 holds the Preclusive Zone active for the specified number of frames after
 the initial triggering event. This is useful in cases where a sudden
 change in light level triggers the Preclusive zone, but the Zone needs to
 be held active for a few frames as the camera itself adjusts to that
 change in light level.



Zone Regions
To modify an existing Zone, from the Zone View click on either the Zone
 region or Zone Name. After making any changes to the Zone Regions, click
 SAVE.
	
	../_images/define-zone-region.png
	Zone Region Definitions

The left side of the display contains the Zone region information. The
 sample shown above shows a Zone region defined by 5 points which is
 intended to watch the driveway for motion. The shape of the region causes
 the analysis methods to ignore the sidewalk and road which are areas that
 are not of interest in this Zone. Separate Zone regions within the monitor
 image area can also be defined for those areas.


[A] Zone Region
Displays an overlay of the current Zone region on the monitor stream. Note
 that the area of the region is proportional to the processing time
 required. Only include areas where motion detection and analysis are
 required. Zone Regions can be any shape as long as they do not
 self-intersect with the outside edges crossing over each other. Colour of
 Region indicates the Zone type with Active shown in red, Inclusive Zones
 are orange, Exclusive Zones are purple, Preclusive Zones are blue,
 Inactive Zones are white and Privacy Zones are black and opaque. Please
 note that the default Region for a newly defined monitor covers the entire
 captured image area. In most cases this is not desired, so it should be
 either deleted or re-defined to cover the area of interest.


[B] Point
Lists the defined region outline Points. Note that Points are generally
 listed in clockwise order with 1 being in the upper left area of the view.
 The currently selected Point is highlighted yellow in the Point list. A
 Point can be defined by dragging the Point in the image or typing specific
 values in the Coordinates boxes. Please note that it is possible to define
 Points outside the image capture resolution area and will prevent the Zone
 from functioning.


[C] Coordinates
Displays the Coordinates of the points with 0,0 being defined as the upper
 left corner of the region. Make sure that all Coordinates are within the
 captured resolution area otherwise the image analysis will not work
 properly or possibly not at all.


[D] Action
Remove or add points. To remove the currently selected point select -. To
 add a new point after the currently selected point click +.
  

[E] Analysis
Allows selection of Showing Analysis or Not Showing Analysis in the Zone
 View. Click on the icon to toggle.


[F] Viewing
Allows Play or Pause the monitor stream in the Zone View. Click on the
 icon to toggle.K/div>


[G] Save / Cancel
Click SAVE to save the currently entered Zone points and parameters. Click
 CANCEL to cancel any changes that have been made to the Zone points and
 parameters.



Other Information
Refer to this user contributed guide in the ZoneMinder Wiki for additional
 detailed information with illustrations if you are new to ZoneMinder and
 need additional help understanding Zone Definition.