US 11,948,373 B2
Automatic license plate recognition
Yi Xu, Belmont, CA (US); Yunchao Gong, Los Altos, CA (US); Suraj Arun Vathsa, Irvine, CA (US); Mayank Gupta, Foster City, CA (US); and Naresh Nagabushan, San Mateo, CA (US)
Assigned to Verkada Inc., San Mateo, CA (US)
Filed by Verkada Inc., San Mateo, CA (US)
Filed on Dec. 12, 2022, as Appl. No. 18/064,883.
Application 18/064,883 is a continuation of application No. 17/871,786, filed on Jul. 22, 2022, granted, now 11,557,133.
Claims priority of provisional application 63/363,442, filed on Apr. 22, 2022.
Prior Publication US 2023/0343113 A1, Oct. 26, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G06V 20/62 (2022.01); G06V 10/774 (2022.01); G06V 20/54 (2022.01); G06V 30/148 (2022.01)
CPC G06V 20/625 (2022.01) [G06V 10/774 (2022.01); G06V 20/54 (2022.01); G06V 30/148 (2022.01)] 17 Claims
OG exemplary drawing
 
1. A method comprising:
analyzing a plurality of frames of a video of an object to detect a license plate associated with the object;
upon detecting the license plate in a frame of the plurality of frames, determining a subset of frames containing the license plate by analyzing neighboring frames associated with the frame to detect the license plate;
determining a plurality of characters in the license plate by, for each character in the plurality of characters:
based on a location of the character in the plurality of characters, determining corresponding characters in each frame in the subset of frames; and
determining, to be a part of the plurality of characters, a most frequent character among the character and the corresponding characters;
obtaining a plurality of bounding boxes indicating locations of the plurality of characters the locations represented by Cartesian coordinates;
obtaining a plurality of nodes based on the plurality of bounding boxes, wherein a respective location of each respective node indicates a respective location of a respective box in the plurality of bounding boxes;
determining a distance based on a first location of a first node of the plurality of nodes and a second location of a second node of the plurality of nodes;
determining whether the distance is below a threshold, wherein the threshold is computed based on a length of a long side of a box of the plurality of bounding boxes;
based on a determination that the distance is below the threshold, creating a first edge between the first and second nodes, thereby obtaining a first graph including the first node, the second node, and the first edge;
determining a leftmost node in the first graph based on first Cartesian coordinates representing the first location and second Cartesian coordinates representing the second location; and
ordering the plurality of characters into a sequence of characters based on the first graph and the leftmost node in the first graph.