Authors of such papers often host their datasets on repositories like GitHub , Kaggle , or Zenodo . If a direct download link is not in the paper's "Resource Availability" section, it is standard practice to contact the corresponding author listed on the first page of the PDF.
This specific count most commonly refers to the mentioned in the paper:
You can access the full paper through the IOP Science portal.
This paper utilizes a dataset consisting of 2,765 jpg images and 2,765 corresponding XML annotation files for vehicle detection. How to access the data:
Vehicle target detection in complex scenes based on YOLOv3