In recent years, the technology of small-scale unmanned aerial vehicles (UAVs) has steadily improved in terms of flight time, automatic control, and image acquisition. This has lead to the development of several applications for low-altitude tasks, such as vehicle tracking, person identification, and object recognition. These applications often require to stitch together several video frames to get a comprehensive view of large areas (mosaicking), or to detect differences between images or mosaics acquired at different times (change detection). However, the datasets used to test mosaicking and change detection algorithms are typically acquired at high-altitudes, thus ignoring the specific challenges of low-altitude scenarios. The purpose of this paper is to fill this gap by providing the UAV mosaicking and change detection dataset. It consists of 50 challenging aerial video sequences acquired at low-altitude in different environments with and without the presence of vehicles, persons, and objects, plus metadata and telemetry. In addition, this paper provides some performance metrics to evaluate both the quality of the obtained mosaics and the correctness of the detected changes. Finally, the results achieved by two baseline algorithms, one for mosaicking and one for detection, are presented. The aim is to provide a shared performance reference that can be used for comparison with future algorithms that will be tested on the dataset.

Learning discriminative, view-invariant and multi-scale representations of object appearance with different semantic levels is of paramount importance for person Re-Identification (ReID). Recently, the community has focused on learning deep Re-ID models to capture a single holistic representation. To improve the achieved results, additional visual attributes and object part-driven models have been considered, inevitably introducing additional human annotation labor or computational efforts. In this paper, we argue that pyramid-inspired methods capturing multi-scale information may overcome such requirements. Precisely, multi-scale pooled regions representing visual information of an object are integrated within a novel deep architecture factorizing them into discriminative features at multiple semantic levels. These are exploited through an attention mechanism later considered in an identification-similarity multi-task loss, trained by means of a curriculum learning strategy. Extensive results on three person ReID benchmarks demonstrate that better performance than existing methods are achieved. Code is available at https://github.com/iN1k1.

Plenty of research has been conducted to obtain the best reidentification performance between a single camera-pairs. None of the current approaches has addressed the reidentification in a camera network by considering the network topology (i.e., the structure of the monitored environment). We introduce a distributed network person reidentification framework which introduces the following contributions. 1) a camera matching cost to measure the reidentification performance between nodes of the network and 2) a derivation of the distance vector algorithm which allows to learn the network topology thus to prioritize and limit the cameras inquired for the matching of the probe. Results on three benchmark datasets show that the network topology can be learned in an unsupervised fashion and network-wise reidentification performance improves. As a side effect, we obtain that the communication bandwidth usage is reduced.