Page History: ROI Element
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Page Revision: 2015/01/26 03:10
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AOI Element
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| Info |
| Category: |
Behaviour Control |
|
AddIn: |
Base Elements |
| Creator: |
OkazoLab Team |
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Scope: |
Parent Event |
| Owns Snippets: |
Triggered |
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Usage: |
Runtime Screen,Snippets |
Properties
Genetic properties
| Name | Description | Attributes | Value Type |
|---|
| Settings |
| Area shape | Defines the shape of the “watched area” | | stTargetShape |
| Border visible | Defines, if a border is shown around the ROI area at runtime. | | Boolean |
| Radar provider | Defines which of the parent events in the layer hierarchy provides the positional data | | String |
| Triggering mode | Defines the conditional mode that trigger the element. | D | stTargetHitMode |
| Fixation duration | Defines the duration (in ms) of the fixation interval when the element works in the "fixation" mode. Otherwise, the value is not used. | D,R | UInt64 |
| Runtime info |
| Is Over | Indicates at the runtime if the positional input is currently inside of the "watched area". | R, Read-only | Boolean |
| Is Triggered | Indicates if the element has been triggered starting from current activation of the parent event. | R, Read-only | Boolean |
| Trigger time | Shows event's time (ms) when the element was triggered. | R, Read-only | UInt64 |
| Visual appearance |
| AntiAliasing | if true, the rendered content will be antialiased for smoother visual appeariance. If false, rendering will be authentic to its source, e.g. a bitmap. | | Boolean |
| Position | Position of the element on the screen area | D,R,* | clPoint
(X.Y,R,Theta) |
| Size | Size of the element | D,R,* | clSize
(Width,Height,
aWidth,aHeight) |
| Z order | Indicates Z Order of the element on the given event | R, Read-only | Int32 |
| Alignment | Defines alignment of the "watched" area to its position. The default value is the central alignment. | D,R,* | stAlignment
Int32 |
| Effects |
| Color mask | Produces a multiplicative combination of the original pixels and the selected mask color (except the alpha channel). The effect emulates a look through a colored glass. White or transparent mask color dont change the original pixels. | D,R,* | clColor |
| Saturation | Saturation of the rendered content. | | Double |
+=== Properties inherited from clElement ===
Inherited properties of clElement
| Name | Description | Constraints | Value Type | Upon Change |
|---|
| Control |
| Is Enabled | If set to false the element is completely omitted when the experiment is run. | | Boolean |
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| Title | Title of the element. | | String |
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Description
AOI element continuously evaluates any tracking data, e.g. the gaze or mouse positions, relatively to a selected region on the screen. The element can also detect specific tracking patterns, e.g perpetual fixations and saccades in and out of the region, and collect timing statistics of such patterns.
Practical use
In the simplest case, the AOI element can be used to report whether a tracking position is inside of the selected screen region. For that purpose, monitor the "Is Over" property of the element at runtime. Another property, "Viewing Time", returns the accumulative time of the tracking position being inside of the selected region between the onset and offset of element's parent event.
In addition, the AOI element can automatically detect and signal the common patterns in a positional data. When the pattern is detected, the element gets triggered. Then the triggering time is recorded and Triggered snippet is invoked, if it's defined. The ROI element can work in one of three triggering modes:
On the first spot
In this mode the element detects when a tracking position input enters the monitored screen region for the first time since the onset of the parent event.
On perpetual fixation
In this mode the element detects when s tracking position enters the monitored region and stays there for a certain time period. The duration of that period is defined by the [Fixation duration] property of the AOI element. The element is not triggered, if any of tracking position goes out of the region before the period is expired. However, the element can be triggered later, if tracking positions returns and stay in the region again.
On fixation break
In this mode the element detect a moment when the input position leaves the element's region (assuming that it has been inside before onset of the parent event). This mode is handy for when breaks in previously archived fixation have to detected.
You can choose only between the rectangular or elliptical shape for the "element's region. It's sufficient for most of scenarios but, however, you can always create radar areas with complex shapes by combining several radar area elements in the same event. In this case, you may need to check the states of multiple radar area elements manually, in your snippets.
Notes
- The radar area element can be triggered only once during activation of the parent event. If you need multiple triggering, redesign your experiment flow (e.g. use several events) or reactivate the parent event. Alternately, reading [Is Over] property of the element will provide a status of positional input even after the element is triggered.
- the radar area element can be affected by the solar visual transformations if they are applied to the parent event. In such cases, relations between positional input and watched areas can be incorrectly estimated. Always place radar area elements in events that have no such transformations.
- if you have several active radar area elements that watch the same screen area they can be triggered at the same time.