Dataset Collection

I have to collect Aerial Images (from drones flying at a height of nearly 30m to 40m) of People Gathering in a Group of 3-4. I have manually checked some images on the internet and looked for some videos on YouTube but these are only images of the dense crowd but what I need is sparse crowd aerial images or YouTube videos or any dataset of same kind. Can someone help me with the appropriate links for the same? I have also found a paper but in it, how it has formed its dataset is not clear to me.