Zone Parameter Explanations - Revision history

Zonemangler: adding redirect to page with new content

2014-05-07T17:52:28Z

adding redirect to page with new content

← Older revision	Revision as of 13:52, 7 May 2014
Line 1:	Line 1:
		#REDIRECT [[Defining Zones]]

Keithboden: Content moved to Defining_Zones

2013-12-22T04:40:04Z

Content moved to Defining_Zones

← Older revision		Revision as of 00:40, 22 December 2013
Line 1:		Line 1:
	Zone configuration and tuning are important when running in the motion detection modes to avoid storing, sorting through, or being alerted on uninteresting video data. Configuring a zone involves setting some basic parameters, as well as choosing an alarm check method and tuning their associated detection parameters.
	~~__TOC__~~

	~~== Basic parameters ==~~
	~~=== 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.

	~~=== Preset ===~~
	The preset chooser sets sensible default values based on computational needs (fast v. best) and sensitivity (low, medium, high.) It is not required that you select a preset, and you can alter any of the parameters after choosing a preset. For a small number of monitors with ZoneMinder running on modern equipment, Best, high sensitivity can be chosen as a good starting point.

	~~=== 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.

	~~=== Region points ===~~
	[[File:Zone - Region sample.jpg\|frame\|right\|The sample region shown to the right shows a region defined by 6 control points. The shape of the region causes the check methods to ignore the sidewalk and areas of the porch wall that receive changing sunlight; two conditions that are not of interest in this zone.]]
	A region is a part of the captured image that is of interest for this zone. By default, a region is configured to cover the whole captured image. Depending on the selected type of this zone, the shape of the region can be adjusted to accommodate multiple effects. This can be done by dragging the control points in the reference image around, or by altering the coordinates found in the controls below the reference image. Clicking on a control point in the reference image highlights the coordinates in the table below. Clicking the + button in a point row adds a control point between this point and the next; clicking the - button removes this control point. It is possible to accidentally place a control point outside of the valid coordinates of the image. This will prevent the monitor from working properly.

	~~=== 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 Methods ==~~
	There are 3 Alarm Check Methods. They are sequential, and are layered: In AlarmedPixels mode, only the AlarmedPixel analysis is performed. In FilteredPixels mode, the AlarmedPixel analysis is performed first, followed by the AlarmedPixel analysis. In the Blobs mode, all 3 analysis methods are performed in order. An alarm is only triggered if all of the enabled analysis modes are triggered. For performance reasons, as soon as the criteria for one of the analysis modes is not met, the alarm checking for the frame is complete. Since the subsequent modes each require progressively more computations, it is a good idea to tune the parameters in each of the activated layers.

	For reference purposes, the Zone Area box shows the area of the entire region of interest. In percent mode, this is 100. In Pixels mode, this is the pixel count of the region. All 3 Min/Max Area parameter groups are based on the Zone Area as the maximum sensible value, and all 3 are interpreted in the units specified in the Units input.

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

	~~==== Min/Max Pixel Threshold (0-255) ====~~
	In the AlarmedPixel 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 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 in an individual pixel will be less.

	The minimum pixel threshold setting should be high enough to cause minor lighting, imaging, or compression changes to be ignored. Setting the minimum value too high, may allow a white cat to walk undetected across the view of the white wall. 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 (indicating that all differences above the minimum threshold are considered a change.)

	~~==== Min/Max Alarmed Area ====~~
	The count of alarmed pixels (or percentage of alarmed pixels relative to the pixel area of the region if in percent mode) is used in this first layer of analysis to determine if an alarm is triggered. If the count or 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 you are trying to capture: 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 region. For example, if you approximate that a subject moving through the frame takes up 30% of the frame, then a good starting minimum area is about 7.5%.

	~~=== FilteredPixels ===~~
	Selecting the FilteredPixels Alarm Check Method adds an additional 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 extraneous alarmed pixels that may be artifacts of the camera, lens, or compression.

	~~==== Filter Width/Height (pixels) ====~~
	This parameter is always specified in Pixels, even when Percentages are the selected units. It specifies the size of the group of pixels surrounding a given pixel that must be in alarmed pixels for the pixel itself to be considered an alarmed pixel. The width and height should always be an odd number. 3 x 3 is the default value, 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.

	~~==== Min/Max Filtered Area ====~~
	Applying the filtering 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 alarm 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, and setting a minimum filtered area parameter less the minimum alarmed area parameter by enough to capture small events of interest.

	~~=== Blobs ===~~
	~~[[File:Zone - 1 blob example.jpg\|frame\|right\|This captured frame shows an image with 1 identified blob. The blob is outlined in the Alarm Colour specified above.]]~~
	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 FilteredPixes 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.
	Selecting the Blobs Alarm Check Method opens up all of the available parameters. Enabling Blobs adds one more layer of analysis to the AlarmedPixel and FilteredPixel checks in the determination of a valid alarm along along with 2 additional parameter categories for tuning: the size of the blobs, and the number of blobs. A Blob is not necessarily the whole object that may be of interest. In the example image, the subject is moving, but only a portion of him is marked as a blob. This is because as the subject moves, many pixels of the image do not change in value beyond the set threshold. A pixel that is representing the subject's shoulder in one frame may be representing his back in the next, however, the value of the pixel remains nearly the same.

	~~==== Min/Max Blob Area ====~~
	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. (There is no upper bound for the size of a contiguous area that will still be considered a blob.)

	~~==== Min/Max 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. 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 can be used to tune out events that show a high number of blobs.

Keithboden: Added area pixel/percent clarification as requested on the talk page.

2013-12-19T03:16:39Z

Added area pixel/percent clarification as requested on the talk page.

← Older revision		Revision as of 23:16, 18 December 2013
Line 39:		Line 39:
	== Alarm Check Methods ==		== Alarm Check Methods ==
	There are 3 Alarm Check Methods. They are sequential, and are layered: In AlarmedPixels mode, only the AlarmedPixel analysis is performed. In FilteredPixels mode, the AlarmedPixel analysis is performed first, followed by the AlarmedPixel analysis. In the Blobs mode, all 3 analysis methods are performed in order. An alarm is only triggered if all of the enabled analysis modes are triggered. For performance reasons, as soon as the criteria for one of the analysis modes is not met, the alarm checking for the frame is complete. Since the subsequent modes each require progressively more computations, it is a good idea to tune the parameters in each of the activated layers.		There are 3 Alarm Check Methods. They are sequential, and are layered: In AlarmedPixels mode, only the AlarmedPixel analysis is performed. In FilteredPixels mode, the AlarmedPixel analysis is performed first, followed by the AlarmedPixel analysis. In the Blobs mode, all 3 analysis methods are performed in order. An alarm is only triggered if all of the enabled analysis modes are triggered. For performance reasons, as soon as the criteria for one of the analysis modes is not met, the alarm checking for the frame is complete. Since the subsequent modes each require progressively more computations, it is a good idea to tune the parameters in each of the activated layers.

			For reference purposes, the Zone Area box shows the area of the entire region of interest. In percent mode, this is 100. In Pixels mode, this is the pixel count of the region. All 3 Min/Max Area parameter groups are based on the Zone Area as the maximum sensible value, and all 3 are interpreted in the units specified in the Units input.

	=== AlarmedPixels ===		=== AlarmedPixels ===

Keithboden: Reorganization, inclusion of a few sample images, and more details. Continuing to look at the source code to try to improve descriptions!

2013-12-19T03:08:39Z

Reorganization, inclusion of a few sample images, and more details. Continuing to look at the source code to try to improve descriptions!

Show changes

Fastolfe: Rework zone descriptions for clarity and concision

2013-11-02T16:28:17Z

Rework zone descriptions for clarity and concision

← Older revision		Revision as of 12:28, 2 November 2013
Line 7:		Line 7:
	==Type==		==Type==
	*Active		*Active
	*:This is the zone type you'll use most often, and which will be set for your default zone. ~~This means that this zone will~~ trigger an alarm ~~on any events that occur within it that meet the selection criteria~~.		*: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		*Inclusive
	*: ~~This zone type can be used for any zones that you want~~ to trigger an alarm ~~only if at least one other Active zone has already triggered one~~. ~~This might be~~ for example ~~to cover an area of the image like~~ a plant or tree ~~which~~ moves a lot ~~and which would trigger lots of alarms. Perhaps this is behind an area you'd like to monitor though~~, in this case you~~'d create~~ an ~~active~~ zone ~~covering~~ the ~~non-moving parts~~ and an ~~inclusive~~ zone ~~covering~~ the ~~tree~~ perhaps with less sensitive detection settings ~~also~~. ~~If something triggered an alarm in the~~ Active ~~zone and also in the Inclusive zone they would both be registered and the resulting alarm would be that much bigger than if you had blanked it out altogether~~.		*: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		*Exclusive
	*: ~~The next zone Type~~ is ~~Exclusive. This means that alarms will only be~~ triggered ~~in this~~ zone ~~if no alarms have already been triggered in Active zones~~. This ~~is the most specialised~~ of ~~the zone~~ types ~~and you may never use it but in its place it is very useful~~. 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.		*: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		*Preclusive
	*:~~This zone type is relatively recent. It is called a Preclusive zone because~~ if it is ~~triggered~~ it ~~actually precludes~~ 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~~. ~~Generally~~ this ~~may~~ be ~~achieved~~ by limiting the maximum number of alarm pixels ~~or other measure in an Active zone. However in some cases that zone may cover an area where the area of variable illumination occurs in different places as the sun and/or shadows move and it thus~~ may be difficult ~~to come up with general values. Additionally~~, if the sun ~~comes~~ out rapidly then although the initial change may be ignored in this way as the reference image catches up an alarm may ultimately be triggered as the image becomes less different. Using one or more Preclusive zones offers a different approach. 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. As always, the best way is to experiment a little and see what works for you.		*: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		*Inactive
	*:This ~~final~~ zone type is the ~~opposite of Active. In this~~ zone type ~~no alarms will ever be reported~~. ~~You can create an~~ Inactive zone to cover ~~any~~ areas in which nothing notable will ever happen or where you get ~~constant~~ false alarms that don't relate to what you are trying to monitor~~. An Inactive zone can overlay other zone types and will be processed first~~.		*: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==		==Units==

Mastertheknife: small corrections and added info about min\max alarmed pixels

2011-06-24T22:11:00Z

small corrections and added info about min\max alarmed pixels

← Older revision		Revision as of 18:11, 24 June 2011
Line 37:		Line 37:
	*Alarmed Pixels -		*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.		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 -		*Filtered Pixels -
Line 50:		Line 50:
	These setting are used to define limits for the difference in value between a pixel and its predecessor in the reference image.		These setting are used to define limits for the difference in value between a pixel and its predecessor in the reference image.

	~~I believe that 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.		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.		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.

	~~The default value for this parameter is X%. Generally, this value may range in the 5% to 15% range.~~

	==Maximum Pixel Threshold==		==Maximum Pixel Threshold==
	See the Minimum Pixel Threshold (above) for some explanation.		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).		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==		==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==		==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)==		==Filter Width and Filter Height (pixels)==

Beardywalrus: /* Type */

2009-01-02T17:40:40Z

Type

← Older revision		Revision as of 13:40, 2 January 2009
Line 6:		Line 6:

	==Type==		==Type==
	*Active -		*Active
			*:This is the zone type you'll use most often, and which will be set for your default zone. This means that this zone will trigger an alarm on any events that occur within it that meet the selection criteria.

	*Inclusive -		*Inclusive
			*: This zone type can be used for any zones that you want to trigger an alarm only if at least one other Active zone has already triggered one. This might be for example to cover an area of the image like a plant or tree which moves a lot and which would trigger lots of alarms. Perhaps this is behind an area you'd like to monitor though, in this case you'd create an active zone covering the non-moving parts and an inclusive zone covering the tree perhaps with less sensitive detection settings also. If something triggered an alarm in the Active zone and also in the Inclusive zone they would both be registered and the resulting alarm would be that much bigger than if you had blanked it out altogether.

	*Exclusive -		*Exclusive
			*: The next zone Type is Exclusive. This means that alarms will only be triggered in this zone if no alarms have already been triggered in Active zones. This is the most specialised of the zone types and you may never use it but in its place it is very useful. 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 -		*Preclusive
			*:This zone type is relatively recent. It is called a Preclusive zone because if it is triggered it actually precludes 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. Generally this may be achieved by limiting the maximum number of alarm pixels or other measure in an Active zone. However in some cases that zone may cover an area where the area of variable illumination occurs in different places as the sun and/or shadows move and it thus may be difficult to come up with general values. Additionally, if the sun comes out rapidly then although the initial change may be ignored in this way as the reference image catches up an alarm may ultimately be triggered as the image becomes less different. Using one or more Preclusive zones offers a different approach. 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. As always, the best way is to experiment a little and see what works for you.

	*Inactive -		*Inactive
			*:This final zone type is the opposite of Active. In this zone type no alarms will ever be reported. You can create an Inactive zone to cover any areas in which nothing notable will ever happen or where you get constant false alarms that don't relate to what you are trying to monitor. An Inactive zone can overlay other zone types and will be processed first.

	==Units==		==Units==

Tburt11: /* Maximum Filtered Area */

2007-06-17T23:08:12Z

Maximum Filtered Area

← Older revision		Revision as of 19:08, 17 June 2007
Line 73:		Line 73:
	==Maximum Filtered Area==		==Maximum Filtered Area==

	* This value ~~shold~~ always be equal to or less than the Maximum Alarmed Area		* This value should always be equal to or less than the Maximum Alarmed Area

	==Minimum Blob Area==		==Minimum Blob Area==

Tburt11 at 23:07, 17 June 2007

2007-06-17T23:07:43Z

← Older revision		Revision as of 19:07, 17 June 2007
Line 1:		Line 1:
	===Zone Parameter Explanations===		===Zone Parameter Explanations===

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

	==Name==		==Name==

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

	==Type==		==Type==

	*Active -		*Active -

Line 20:		Line 17:

	==Units==		==Units==



	*Pixels - Selecting this option will allow many of the following values to be entered (or viewed) in units of pixels.		*Pixels - Selecting this option will allow many of the following values to be entered (or viewed) in units of pixels.
Line 28:		Line 23:

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

Line 36:		Line 30:

	==Alarm Check Method==		==Alarm Check Method==

	*Alarmed Pixels -		*Alarmed Pixels -

Line 54:		Line 47:
	I believe that 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.		I believe that 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, ~~would~~ allow a white cat to walk undetected across the view of the white wall.		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.

	The default value for this parameter is X%. Generally, this value may range in the 5% to 15% range.		The default value for this parameter is X%. Generally, this value may range in the 5% to 15% range.

	==Maximum Pixel Threshold==		==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==

			==Maximum Alarmed Area==

	==Filter Width and Filter Height (pixels)==		==Filter Width and Filter Height (pixels)==

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

Line 69:		Line 68:

	==Minimum Filtered Area==		==Minimum Filtered Area==

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

	==Maximum Filtered Area==		==Maximum Filtered Area==

			* This value shold always be equal to or less than the Maximum Alarmed Area

	==Minimum Blob 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==		==Maximum Blob Area==
			This parameter is probably best left at the default value of 0 (zero) or disabled.

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

Tburt11: /* Minimum Pixel Threshold */

2007-06-17T22:40:20Z

Minimum Pixel Threshold

← Older revision		Revision as of 18:40, 17 June 2007
Line 50:		Line 50:

	==Minimum Pixel Threshold==		==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.

			I believe that 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, would allow a white cat to walk undetected across the view of the white wall.

			The default value for this parameter is X%. Generally, this value may range in the 5% to 15% range.

	==Maximum Pixel Threshold==		==Maximum Pixel Threshold==