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Navigation: Gatekeeper > Optimise ANPR

Add the USBCameraAxon for ANPR

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In order to perform ANPR, the USBCameraAxon must be connected to the LoadBalanceAxon, that is feeding the ANPRAxons in the Cortex (see example Cortex below).

In order to feed the proper images to the ANPR engine and obtain high accuracy levels, the region of interest has to be set.

 

To select the Region of Interest for the color camera (USBCameraAxon), the ImgCropAxon  is used.

The ImgCropAxon is responsible to select/crop a part of an image used in for instance two lane recognition.

The ImgCropAxon does not change the settings of the sensor itself. It crops the images coming from the sensor. The cropped image is send further down the Cortex.

 
By choosing the proper ROI('s) processing speed of recognition will increase significantly.

 

In case of multiple regions of interest are required,  the USBCameraAxon needs to be connected with multiple ImgCropAxons (see the design of the Cortex below). One ImgCropAxon can make one crop

 

1. The design of the Cortex

 

GK_add_USBCamera_ANPR_CortexDesign

 

 

 

2. The corresponding CortexView and the steps to configure VideoSourceAxon for ANPR

 

CC_select_ROI_VideoSourceAxon

 

 

1.In the view two ImgCropAxons (ImgCrop0 and ImgCrop1) viewpanels are seen at the left, each with their own cropped ROI. ** Make the ROI as small as possible still covering the complete recognition area. The smaller the area the faster and more accurate recognition processing will be.

 

2.The GatekeeperAxon viewpanel (right-top) shows the cropped ROI's with an ANPR overlay. To enable the overlay, right click the image and choose 'anpr'. Read more about the overlay and the meaning of the numbers here.
 
When the overlay is not visible the license plate is not recognised. The license plate is either too large or too small.
Another reason could be, that the ANPRAxons are not configured accurately or the minimum license plate size is not set properly in the ANPRThresholdAxon..
 

3.The ANPRThresholdAxon viewpanel (right_bottom) displays hitcount, max and min width of the license plate.
The settings in the ANPRThresholdAxon are global, meaning they concern all video streams, no individual threshold can be set per video stream.

 

 

**Crop the image

An image can be cropped by holding the left mouse button and drag and select the region of interest.

 

The cropped part of the image will be displayed on its original image position. It will not be resized to fill the panel.

This way the exact crop can be seen. A new selection can be made without resetting to its original size.

 

The ImgCropAxon can only be used for uncompressed images.