Unsupervised Vehicle Search in the Wild: A New Benchmark

In urban surveillance systems, finding a specific vehicle in video frames efficiently and accurately has always been an essential part of traffic supervision and criminal investigation. Existing studies focus on vehicle re-identification (re-ID), but vehicle search is still underexploited. These methods depend on the locations of many vehicles (bounding boxes) that are not available in most real-world applications. Therefore, the unsupervised joint study of vehicle location and identification for the observed scene is a pressing need. Inspired by person search, we conduct a study on the vehicle search while considering four main discrepancies among them, summarized as: 1) It is challenging to select the candidate regions for the observed vehicle due to the perspective differences (front or side); 2) The sides of the same type of vehicles are almost the same, resulting in smaller inter-class; 3) Lacking satisfied dataset for vehicle search to meet the practical scenarios; 4) Supervised search publishing methods rely on datasets with expensive annotations. To address these issues, we have established a new vehicle search dataset. We design an unsupervised framework on this benchmark dataset to generate pseudo labels for further training existing vehicle re-ID or person search models. Experimental results reveal that these methods turn less effective on vehicle search tasks. Therefore, the vehicle search task needs to be further developed, and this dataset can advance the research of vehicle search. Https://github.com/zsl1997/VSW.