Extracting features for a directory of images

[tejas1995]

I'm slightly confused by the instructions on how to extract features from the test_sg_net.py script - more specifically:

• what format the data directory has to be in (i.e. something more than just a directory containing images) and
• what variables need to be set in the sgg_configs/vgattr/vinvl_x152c4.yaml config in order to point to my data directory (I'm not sure what the variables DATASETS.TEST and DATA_DIR need to be - I assumed the latter was the directory with all the images I need features for, but that does not seem to be the case)

[hanxiaotian]

This is a similar question to https://github.com/microsoft/scene_graph_benchmark/issues/7#. You can follow vinson2233 detailed comment https://github.com/microsoft/scene_graph_benchmark/issues/7#issuecomment-819357369