Drawing Region of Interest

This page explains how to draw Region of Interest (ROI) for analytic Vehicle Counting, People Counting, License Plate Recognition, and Crowd Estimation.

How to Use ROI Lib

  1. Clone this library.

2. To be able to draw inside the canvas, make sure to copy the give canvas as an id to the component.

3. Make sure to copy all the #canvas styling, image for preview can be but inside of the canvas element as children component. for example:

<div id="canvas">
	<img src={source} />
</div>

4. Call initialCanvas function on windows onload, or when there are any ROI Type change

Function Explanation

initialCanvas ( callback, roi_type )

initialCanvas needs two parameters, namely for callback and roi_type respectively. callback will be called after region or line created, returning object with values:

{
	points:  array_of_coordinates,
	area:  name_of_area,
	color:  color_of_lines,
	lineNumber: index_of_roi (starts from 1)
}

onResetROI ( callback )

this function will remove all the lines. accepting callback params for user to be able to call their own function when resetting all lines and region

onDeleteLine ( id ), onDeleteRegion (id)

receive id as params. this id can be filled with lineNumber from the initialCanvas callback. onDeleteLine will be used to delete lines, while onDeleteRegion will be used to delete area/region.

onReverseLine ( id )

receive id as params. this id can be filled with lineNumber from the initialCanvas callback. only applicable to roi_type line. will reverse the line direction

Result

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