Overview Region of Interest (ROI) Node

Overview Region of Interest (ROI) Node

The Region of Interest (ROI) node allows to filter a portion of an image that you want to perform some other operation on.

ROI can be set for each camera stream and is therefore device specific. While the ROI node needs to be added to your flow, it will be configured in the Local Configuration settings, not inside the Viso Builder.

To access the local configuration settings and setup your ROIs, follow the guide here.

Name: You can set a name for your ROI node. This is especially important if you are using multiple camera input streams and multiple ROI nodes in your flow.

ROI Type: The ROI node allows you to select from three types of ROIs, depending on your use case:
  1. Rectangle: The rectangle ROI type is used for counting use cases. It allows you to define the "counting area" in the image (blue rectangle) and position the crossing line (red). Objects crossing this line will be counted (IN/OUT). If you select "Crop ROI", then the image will be cropped to the ROI size to increase inference performance.

    Additionally, the rectangle type allows you to rotate the incoming frames. You will need that for example in the case you are using a fisheye camera and want to count people at the entrance of a room. For optimal performance with the given algorithm, you might want to have the entrance on top of the image and count people crossing the line horizontally.

  2. Polygon: The polygon ROI type allows you to set your region of interest as a polygon. This might be used if you, for example, want to detect objects only in a specific area of a specific shape (e.g. intrusion detection). Once you have set your polygon, you will be prompted with a popup to give your ROI a name. This allows you to have multiple polygon ROI on the same input stream.

    Additionally, you will see the option to "exclude an ROI". This option will be helpful if you would like to set certain areas in which no objects should be detected.

  3. Section: The section ROI type allows you to define multiple sections in a video frame. You can flexibly adjust the number of sections, grid, area names and colors. This type of ROI is useful if you would like to track objects across sections, as an example. Similarly to the polygon type, you have the option to "exclude" sections.

Input and Output:  The ROI node has one input and one output. The input connects the ROI node with a previous node such as video feed, and the output sends the results to the next node such as Object Detection.

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