Firstly you need to prepare the dataset and pre-trained models as described here.
Then modify the directories by
cd ${EgoNet_DIR}/configs && vim KITTI_inference:demo.yml
Edit dirs:ckpt to your pre-trained model directory.
Edit dataset:root to your KITTI directory.
Finally, go to ${EgoNet_DIR}/tools and run
python inference.py --cfg "../configs/KITTI_inference:demo.yml" --visualize True --batch_to_show 2
You can set --batch_to_show to other integers to see more results.
The visualized 3D bounding boxes are distinguished by their colors: