tools/misc/download_dataset.py supports downloading datasets such as COCO, VOC, LVIS and Balloon.
python tools/misc/download_dataset.py --dataset-name coco2017
python tools/misc/download_dataset.py --dataset-name voc2007
python tools/misc/download_dataset.py --dataset-name voc2012
python tools/misc/download_dataset.py --dataset-name lvis
python tools/misc/download_dataset.py --dataset-name balloon [--save-dir ${SAVE_DIR}] [--unzip]