First, set up the datasets following GETTING STARTED.md.
The model is trained progressively with different stages (0: static images; 1: BL30K; 2: longer main training; 3: shorter main training). After each stage finishes, we start the next stage by loading the latest trained weight. For example, the base model is pretrained with static images followed by the shorter main training (s03).
To train the base model on two GPUs, you can use:
python -m torch.distributed.run --master_port 25763 --nproc_per_node=2 train.py --exp_id retrain --stage 03(NOTE: Unexplained accuracy decrease might occur if you are not using two GPUs to train. See hkchengrex#71.)
master_port needs to point to an unused port.
nproc_per_node refers to the number of GPUs to be used (specify CUDA_VISIBLE_DEVICES to select which GPUs to use).
exp_id is an identifier you give to this training job.
See other available command line arguments in util/configuration.py.
Unlike the training code of STCN, batch sizes are effective. You don't have to adjust the batch size when you use more/fewer GPUs.
We implemented automatic staging in this code base. You don't have to train different stages by yourself like in STCN (but that is still supported).
stage is a string that we split to determine the training stages. Examples include 0 (static images only), 03 (base training), 012 (with BL30K), 2 (main training only).
You can use tensorboard to visualize the training process.
The model files and checkpoints will be saved in ./saves/[name containing datetime and exp_id].
.pth files with _checkpoint store the network weights, optimizer states, etc. and can be used to resume training (with --load_checkpoint).
Other .pth files store the network weights only and can be used for inference. We note that there are variations in performance across different training runs and across the last few saved models. For the base model, we most often note that main training at 107K iterations leads to the best result (full training is 110K).
We measure the median and std scores across five training runs of the base model:
| Dataset | median | std |
|---|---|---|
| DAVIS J&F | 86.2 | 0.23 |
| YouTubeVOS 2018 G | 85.6 | 0.21 |
You can start training from scratch, or use any of our pretrained models for fine-tuning. For example, you can load our stage 0 model to skip main training:
python -m torch.distributed.launch --master_port 25763 --nproc_per_node=2 train.py --exp_id retrain_stage3_only --stage 3 --load_network saves/XMem-s0.pthDownload them from [GitHub] or [Google Drive].