Multi-Dilation Network for Crowd Counting

With the growth of urban population, crowd analysis has become an important and necessary task in the field of computer vision. The goal of crowd counting, which is a subfield of crowd analysis, is to count the number of people in an image or a zone of a picture. Due to the problems like heavy occlusions, perspective and luminous intensity variations, it is still extremely challenging to achieve crowd counting. Recent state-of-the-art approaches are mainly designed with convolutional neural networks to generate density maps. In this work, Multi-Dilation Network (MDNet) is proposed to solve the problem of crowd counting in congested scenes. The MDNet is made up of two parts: a VGG-16 based front end for feature extraction and a back end containing multi-dilation blocks to generate density maps. Especially, a multi-dilation block has four branches which are used to collect features in different sizes. By using dilated convolutional operations, the multi-dilation block could obtain various features while the maximum kernel size is still 3 x 3. The experiments on two challenging crowd counting datasets, UCF_CC_50 and ShanghaiTech, have shown that the proposed MDNet achieves better performances than other state-of-the-art methods, with a lower mean absolute error and mean squared error. Comparing to the network with multi-scale blocks which adopt larger kernels to extract features, MDNet still gains competitive performances with fewer model parameters.