Key point calibrating and clustering for hard example mining of dense analogs in the fish-eye lens

Recent years have witnessed widespread applications of the fish-eye lens with a wide field-of-view. However, its inherent distortion poses a big challenge to the intelligent recognition of dense analogs (IRDA) by convolutional neural networks (CNN). The major bottleneck of existing CNN models lies in their limited modeling capacity for distorted objects in fish-eye images, leading to the misclassification of hard examples. To further improve the accuracy of IRDA, we propose a novel key point calibrating and clustering (KPCC) algorithm based on the hemispherical projection model. Our method can effectively correct the hard example misclassification predicted by the CNN, significantly enhancing the performance of the IRDA. The experiments show that, as a light-weight computation calibrating and stable adaptive clustering method, the KPCC increases the precision and recall rate of IRDA on the intelligent retail dataset by 8.55% and 8.07%, respectively; compared with the classic Focalloss, QFocalloss, and OHEM (online hard example mining), it can mine hard examples more sufficiently, especially in the scene of distorted dense analog detection.